Astronomy

How can we tell the age of a rogue planet?

How can we tell the age of a rogue planet?

Is it possible to find out how old is a planet, especially a rogue planet? I know that people measured the radioactive decays to determine Earth's age with some amazing accuracy, but what about interstellar planets be, they gas or terrestrial?


At the moment there is basically only one way. That is to associate the planetary-sized object with a cluster of stars or moving group of stars of known age.

That's basically it. If the planetary-sized object really can't be associated with another object, then only limits can be placed on its age by comparing it's luminosity to theoretical planet cooling models. But to use these models you need to know the mass!

So at the moment, the only "free-floating" planetary mass objects known (they could all be low-mass brown dwarfs actually) are those for which an age is estimated by association and therefore a (planetary) mass has been deduced from cooling models.


Jesus Told His Disciples What the End Starts With, But Do You Understand It?

Jesus’ disciples asked him the very question that every Christian still wonders today: how do we know when you’re coming back? Amazingly, Jesus answered by giving the actual "signs of his coming and the end of the age." He didn’t refuse! We can read his straightforward answer in Matthew, Mark and Luke. Yet Christians don’t understand his answer as evidenced by how they fall for every speculative counterfeit end time sign theory hatched by Christian prophecy theorists in its place. Find out what you’ve been missing in Jesus’ answer so you understand the real signs of his coming and never have to fall for another false prophecy theory again.


In the Late-2020s a microlensing survey could tell if Rogue planets are more common than planets around Stars

The Wide Field Infrared Survey Telescope (WFIRST) is a proposed infrared space observatory which was selected by National Research Council committee as the top priority for the next decade of astronomy. The WFIRST space telescope could be in space by 2024 if it is started in 2017.

Estimates suggested that every planetary system in the galaxy booted at least one planet into interstellar space. With billions of planetary systems in the Milky Way, there may be billions, maybe even hundreds of billions, of rogue planets in the galaxy, says planetary scientist Sara Seager of MIT.

“A census of rogues,” Liu says, “is the only way we are going to fully understand the extent of what’s out there in the Milky Way.”

Two traits distinguish a star from a brown dwarf and to an extent, from a planet: mass and the presence or absence of nuclear fusion. Stars, even small ones, are at least 80 times the mass of Jupiter, which at 318 times the mass of Earth is the most massive planet in the solar system — and is often used by astronomers to gauge the size of other gaseous objects. According to theoretical calculations about how stars work, objects must be 80 Jupiter masses or more to fuse hydrogen nuclei (protons) into helium. This process liberates energy, which is how stars burn bright, speckling the night sky.

Brown dwarfs are smaller, anywhere between 13 and 80 Jupiter masses. They are not dense enough to fuse hydrogen. But they may have been big and hot enough to fuse deuterium nuclei (a proton plus a neutron) with protons or other nuclei, which means they once generated energy but no longer do.

Any sphere less than about 13 Jupiter masses is not large or dense enough to fuse any kind of atomic nuclei. As a result, some astronomers define orbs with less than roughly 13 Jupiter masses — even untethered ones — as planets.

One study suggests there could be 100,000 rogue planets for every star in the Milky way.

MASS MATTERS Small stars, brown dwarfs and rogue planets can be similar in diameter but have different masses. Mass is one characteristic used to distinguish the objects. However, for classification purposes, astronomers may need to look beyond mass to consider how an orb formed and what elements it’s made of.
FROM LEFT: JUT13/ISTOCKPHOTO NASA SEGRANSAN ET AL/A&A 2008 LEECH ET AL/ASP CONFERENCE SERIES 2000 LIU ET AL/APJ LETTERS 2013

Abstract -Astronomy and Astrophysics – CFBDSIR2149-0403: a 4–7 Jupiter-mass free-floating planet in the young moving group AB Doradus?

Using the CFBDSIR wide field survey for brown dwarfs, we identified CFBDSIRJ214947.2-040308.9, a late T dwarf with an atypically red J − KS colour. We obtained an X-Shooter spectra, with signal detectable from 0.8 μm to 2.3 μm, which confirmed a T7 spectral type with an enhanced Ks-band flux indicative of a potentially low-gravity, young object. The comparison of our near infrared spectrum with atmosphere models for solar metallicity shows that CFBDSIRJ214947.2-040308.9 is probably a 650−750 K, log g = 3.75−4.0 substellar object. Using evolution models, this translates into a planetary mass object with an age in the 20−200 Myr range. An independent Bayesian analysis from proper motion measurements results in a 87% probability that this free-floating planet is a member of the 50−120 Myr-old AB Doradus moving group, which strengthens the spectroscopic diagnosis of youth. By combining our atmospheric characterisation with the age and metallicity constraints arising from the probable membership to the AB Doradus moving group, we find that CFBDSIRJ214947.2-040308.9 is probably a 4−7 Jupiter mass, free-floating planet with an effective temperature of

4.0, typical of the late T-type exoplanets that are targeted by direct imaging. We stress that this object could be used as a benchmark for understanding the physics of the similar T-type exoplanets that will be discovered by the upcoming high-contrast imagers.

SOURCES- Wikipedia, youtube, NASA, Science News

Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.

Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.

A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.


Astronomers Have Investigated a Weird, Isolated Planet-Like Object

Back in 2012, astronomers spotted a perplexing isolated object in our galactic neighbourhood - an object more massive than Jupiter, that looked very much like one of the closest rogue planets we'd ever found. The only problem was, it wasn't like any rogue planet we'd previously seen.

Now scientists has investigated the strange object, known as CFBDSIR 2149-0403, and found evidence that it might not actually be a planet after all, and it's more 'rogue' than we expected.

Although most planets are found neatly orbiting a host star, in recent years it's becoming increasingly common for scientists to detect the occasional 'rogue planet' - a planet that's either been kicked out of its star system, or never had one in the first place, and is now orbiting the entire galaxy.

When researchers found CFBDSIR 2149-0403 back in 2012, they were particularly excited, as it appeared to be the closest rogue planet we'd ever detected, at just a little over 100 light-years away.

It's always hard to determine whether these rogue planet candidates are actually planets, as opposed to brown dwarfs - substellar objects that are heavier than the heaviest planets in the known Universe, but lighter than the lightest stars, and don't quite have enough mass to sustain nuclear fusion.

But based on what researchers could tell about CFBDSIR 2149-0403 at the time, they concluded that it had a mass roughly four to seven times that of Jupiter, making it a rogue planet candidate (the lower cut-off for brown dwarfs is more than 13 times more massive than Jupiter).

It was also suggested that the supposed rogue planet was most likely travelling as part of something called the AB Doradus moving group - a group of objects orbiting our galaxy together that all are roughly the same age, and therefore most likely formed in the same location.

Based on that assumption, CFBDSIR 2149-0403 was predicted to be a relatively young 50 to 120 million years old.

The only problem with the assumption that CFBDSIR 2149-0402 was a rogue planet was that it was based soley on a handful of initial observations.

The conclusion wasn't widely accepted by the scientific community - especially since there was also no evidence that the object had formed as a planet and been objected from any star system.

To figure out what was really going on, a team of researchers led by Philippe Delorme from the Grenoble Alpes University in France, one of the astronomers to first find CFBDSIR 2149-0403, observed the object over the past few years, using multiple telescopes across multiple wavelengths.

And it turns out the object is even weirder than initially thought.

First off, based on the new observations, the team got a more precise estimation of its location and where it's travelling, and concluded that CFBDSIR 2149-0403 can't be part of the AB Doradus moving group.

"Our new . parallax and kinematics safely rule out membership to any known young moving group, including AB

That's both good and bad news for classifying what the object actually is, because although it gives us new information, it also removes the age constraints that were previously in place.

"Though determining that certainly improved our knowledge of the object it also made it more difficult to study, by adding age as a free parameter," Delome told Tomasz Nowakowski from Phys.org.

The team also discovered that the object either has low gravity, or unusually high metal content, referred to as high metallicity. And the new observations made them less certain of the object's mass, which means they can no longer say confidently that it's a planet rather than a brown dwarf.

Based on these findings, we're left with two hypotheses: CFBDSIR 2149-0403 is either a young (less than 500 million years old) rogue planet, between two and 13 times the mass of Jupiter or it's an older (2 to 3 billion years old) highly metallic brown dwarf, with a mass ranging from two to 40 times the mass of Jupiter.

Or maybe it's something else entirely.

"CFBDSIR 2149-0403 is an atypical substellar object that is either a 'free-floating planet' or a rare high-metallicity brown dwarf. Or a combination of both," Delorme told Phys.org.

The results have been published on pre-print site arXiv.org ahead of peer-review, so until we have others in the astronomy community scrutinise and independently verify them, we need to be skeptical.

But the good news is that CFBDSIR 2149-0403 is relatively close to us, so we can continue to observe it to gain a better understanding of the nature of rogue planets or brown dwarfs.

And it might even be our first chance to study a whole new class of planet-like object we haven't yet defined.


Astronomers discover a bizarre rogue planet wandering the Milky Way. The free-range planet, which is nearly 13 times the mass of Jupiter and does not orbit a star, also displays stunningly bright auroras that are generated by a magnetic field 4 million times stronger than Earth's.

I'm thinking it will come up in this thread too, so I'll share a question u/voelkar asked over on r/astronomy while I have a minute.

Eli5: How does it have Auroras if it isnt orbiting a sun?

This is a great question! We get our auroras here on Earth thanks to the solar wind, which is a constant flow of energetic charged particles coming from the Sun. As these particles get close to Earth, they are guided toward the poles of our planet by our global magnetic field. And when they eventually hit molecules in the upper atmosphere, we get the beautiful auroras known as the northern and southern lights.

However, Jupiter also has auroras, but the solar wind should be so weak way out there that there must be another way auroras can be produced. And astronomers are pretty sure there is. Specifically, they think that Jupiter does not get bombarded by (as many) charged particles from the solar wind, but instead gets hit with charged particles coming from Io, which is loaded with volcanoes. Just like on Earth, these charged particles ride down Jupiter's magnetic field lines until they strike the upper atmosphere near its poles.

According to the study, the researchers think that this starless exoplanet may have a moon of its own, which would explain the auroras. But then again, there is always the possibility that something else is bombarding it with charged particles!

Edit: I figured I should add this too. On r/space, u/musubk gave a great explanation below of how a moon can help a planet generate auroras.

Jupiter's moons produce auroral footprints because they have atmospheres, and as those atmospheres move through Jupiter's magnetic field some of the particles are stripped from the atmosphere and ionized through collisions with plasma particles embedded in the field. The newly charged particles then move along field lines which are connected to Jupiter and excite particles within Jupiter's atmosphere, creating aurora. Io has a particularly bright auroral footprint because it has a lot of volcanic activity keeping its atmosphere inflated and prime to be stripped by Jupiter's magnetic field.

There's a more in-depth description on the Io wikipedia page though it seems to assume the reader has some familiarity with plasma physics jargon.


Ep. 286 How to Debunk an End-of-the-World Myth

Everyone is always predicting the end of the world. Someone’s going to tell you that this the year that it’s all going to end… the end of planet Earth… and they’re always wrong. But, someone will eventually be right. Planet Earth is doomed, lets figure out how.

Show Notes

Transcript: How to De-Bunk an End of the World Myth

Fraser: Hi, Everyone. It’s Fraser here. So this is the third episode that we recorded during the “Not the End of the World” cruise in front of our live audience. So, again, I apologize again for the audio quality. We recorded this on a portable audio device, so you can definitely hear the audience in the background, which is great — adds to the live show. So this corresponds to episode 286: “How to De-bunk an End of the World Myth,” and this is for December 24, 2012. Enjoy the show!
[begin live recording]

Fraser: Everyone’s always predicting the end of the world. Someone’s going to tell you that this is the year it’s all going to end, the end of the planet Earth, and they’re always wrong, but someone will eventually be right. Planet Earth is doomed. We have to figure out how. This is my favorite topic ever. We’re going to talk about all of the ways the Universe is just trying to kill planet Earth. So first, just to put this into context, how long has the Earth been around?

Pamela: Somewhere around 5 billion years. Exact numbers are still being argued, so I’m just going to go with 5 billion is a good starting point. 5.5 is out there, 6 is out there somewhere…
Yeah, right. So all of the ways, all of the dark forces working against our planet have failed so far.

Pamela: All the real nemesises.

Fraser: For almost 5 billion years, all failed, and here we are still, and yet the end of the world is [missing audio]. In fact, as we’re recording this, we’re about to…

Pamela: So the end of the world is always nigh because the Universe truly is trying to destroy life as we know it on the planet Earth, whether it be a random black hole that comes tumbling into our area of space and out of nowhere starts sucking in materials, or a comet comes colliding toward our planet out of the Sun and we don’t see it until, well, we’re about to die. There are so many ways that every day we somehow survive miraculously, except really it’s just probability.

Fraser: OK, so let’s take a look at some of the kinds of classes of ways that our planet could end, and I think we should be really clear to distinguish between the ways that we can kill ourselves, or the ways that human beings can be killed…

Pamela: Those are almost as numerous.

Fraser: No, I understand that, but those are easy. It’s easy to kill all of humanity, ways to kill all life, which would be a lot tougher, and then ways to actually destroy the planet right down to its very essence.

Pamela: Which at the end of the day is by far the coolest thing to discuss.

Fraser: And difficult. Yes. OK, let’s talk about humanity. I think most people talk about that they are, we’re going to…we need to save Earth, we need to protect the Earth. That’s not what we need to do. We actually need to stop killing all of ourselves.

Pamela: And protecting…

Fraser: …and the environment

Pamela: We’re going through a mass extinction right now.

Fraser: Yeah. Absolutely.

Pamela: Within our lifetime, we will probably lose the black rhino. So this is where people are working hard to try and gather seeds, gather genetic samples against that future just like when people are now trying to resurrect the woolly mammoth that was killed off by human hunters. Well, someday we may need to resurrect a whole lot more.

Fraser: What are some of the ways that we are potentially going to destroy the planet? Sorry – destroy humanity.

Pamela: Destroying humanity starts with viruses and bacteria at a certain level. There is always that inquisitive scientist who forgets the power that he has to destroy everything. If you ever want to terrify yourself, read White Plague by Frank Herbert.

Fraser: Well, I always think about this – that in the olden days, if you wanted to create a nuclear weapon, you need to have the sum capability of a super power, and then you could create a nuclear weapon, and then over time, these viruses and genetic stuff… it’s getting easier and easier. Eventually, you can imagine. it’s going to be, in the end, some hacker kid…

Pamela: Well, worse than that, you have bored individual working at a drug company with full access to the labs, full access to state-of-the-art equipment going in after hours, toodling away at what they think is going to be the next way to genetically engineer a cure to some horrible thing, and there’s that one gene off. We had scientists who created silly putty, which is “win,” while not trying to do it.

Fraser: Not trying to destroy humanity. Right. Yeah. Of course.

Pamela: So if people trying to create new adhesives can create post-it notes, which are awesome, but not that sticky, you have to worry about what someone manipulating genes and viruses could do by accident.

Fraser: Someone’s going to accidentally make a virus, kill us all, OK, let’s move on. [laughing] You know, we can harm the environment enough that it can’t support life, right? We [missing audio] on that right now.

Pamela: That’s kind of the awful, evil, ugly…

Fraser: Is everyone depressed yet? This is going to get a lot worse too. I love these shows.

Pamela: So then there’s the fact that we live in a developing world. We live, you and I, in developed nations, but the rest of the world is working to get to the same one-car-per-driver’s-license-in-the-household that we experience in so many parts of the United States. And as we increase the number of cars, as we increase the number of television sets, as we increase the infrastructure that humans have to travel and entertain themselves, this requires massive loads on our manufacturing, our shipping. Amazon Prime, something I am guilty of using, is destroying the world one overnight shipment at a time.

Fraser: See, and as a Canadian, I do not have access to Amazon Prime, so I am really doing my part for humanity.

Pamela: My husband and I compensate for you.

Fraser: Yeah. OK. Alright. Push those boxes around your house with a snowplow.

Pamela: Yeah. Sadly, yeah.

Fraser: So, OK, we’re going to sort of make the environment unlivable for humanity, and there’s always these weird things that we could be doing as well when you think about some of the [missing audio] some kind strange matter…

Pamela: That’s not going to destroy the Earth. That might lead to…

Fraser: It would destroy the whole Universe, right? And we live in the Universe.

Pamela: We do, but that one falls on the statistically as likely as monkeys to create Shakespeare.

Fraser: …with devastating effects.

Fraser: But yeah it’s not going to happen. No. Seeing risk analysis, that’s all I’m saying.

Pamela: So CERN can create a micro-black hole, and that would be awesome because if it happens to evaporate, Steven Hawking finally gets his Nobel prize because theorists don’t get Nobel prizes until what they theorize actually happens, so we kind of need to evaporate a black hole for him. The man deserves it. But if it doesn’t evaporate, we now understand more about the Universe, and we end up with a microscopic black hole very, very, very slowly nomming the center of our planet, which is fine because it’s only going to eat an atom every few decades. That’s OK.

Fraser: So why are we talking about this black hole?

Pamela: Because it’s awesome if we get Steven Hawking the Nobel prize.

Fraser: OK, so we’ve talked a bit about the kinds of ways that humanity could kill itself, so what are some of the ways that we’re not going to do it, just humanity.

Pamela: Just humanity.

Fraser: Well, think about like an asteroid. It’s going to come in…

Pamela: It’s going to affect everything.

Fraser: It’s going to affect everything. We’re part of everything.

Pamela: So a stupid way that it would affect only humanity, that would devastate our way of life is we actually are running out of helium.

Pamela: This is one of those things people don’t think about.

Fraser: Save your balloons!

Pamela: Think about the florist because the price of helium balloons is currently going through the roof, and the reason for this is because helium is really a disposable gas. Once helium gets into the Earth’s atmosphere, it is such a light gas that any random collision with an oxygen molecule could put it on a trajectory out of Earth’s environment. It could hit, well, escape velocities through that type of collision. Helium, once in the atmosphere, is destined to leave our atmosphere. So as we mine helium as part of other ways that we’re getting gases and, well, petroleums out of our soils, eventually we’re going to run out of helium. This is something people don’t worry about, but if we run out of helium, that destroys industry, it destroys science because we use helium to cool so many different things.

Fraser: There was a great theme, I’m trying to remember, I’m sure someone’s going to remember the name of this book, but there’s a great quote about how we as human beings have really gotten all the easily accessible resources on the planet Earth. We’ve gotten all the chunks of iron, and platinum and gold that were just sitting around on the surface of the Earth, so if we do go through some kind of mass die-off, or real devastating impact to our way industrial way of life, it would be really, really difficult for any following civilization to do that because we’re at the point now where we’ve got massive oil fields [missing audio].

Pamela: We went from you stab a stick into the ground in Beaumont, TX and out shoots oil to “Oh, crud. We have to dig a kilometer into the ground.”

Fraser: You have to tear apart northern Alberta.

Pamela: There will be no second Bronze Age. This is it. If we destroy our civilization, you have to wait…well, think of how long it’s been since the dinosaurs died. That’s how long it took for them to become oil.

Fraser: So there are all of these kinds of events that are going to impact humanity, but now to actually kill…OK, enough “humanity is in trouble.” Let’s move on to life — all life on Earth. What would it take to wipe out all life on Earth?

Pamela: All life on Earth gets tricky because even an asteroid or a comet coming in, unless it’s like a Mars-sized or a Mercury-sized object, in which case it’s no longer an asteroid or a comet, it’s a rogue planet that does not actually exist!

Fraser: Right. Nibiru, Planet X…

Pamela: So the reality is a lot of the things that we freak out about (asteroids and comets) are a real concern because they can wipe out large parts of the planet. You can imagine if an asteroid hit, say, off the Pacific coast, everyone up to the Rockies – dead. That’s a bad day.

Fraser: That’s back to us again, right?

Pamela: Well, everything. We would lose all the redwoods. Losing redwoods would be a bad day.

Fraser: What about the fish? The fish are OK.

Pamela: Not necessarily…the ones that were right there, some of them are now in orbit.

Fraser: [laughing] Right! OK, so the orbital fish – not so happy, but the rest of the fish, until of course we get this great column of shrieking hail of rock and steam that fill the whole Earth and lights all of the forest on fire and burns, but even then it’s not going to kill all the life.

Pamela: The worst case in terms of asteroids is — and this is when it gets scary when you go to Planetary Science conferences, is if you have a comet or asteroid headed toward planet Earth, and we realize this far enough in advance, you can do things like try to steer it, blow it up, things like that. Now the energy necessary to actually blow up an asteroid, we don’t have that kind of energy, not a concern, but you can certainly remove chunks off the surface in the process of trying to steer it in a new direction. So you can imagine, and there’s Soviet, former Soviet, Russian students trying to actually do this in the future to practice. You can imagine you take an asteroid, you attach explosives to it, to fire the explosives to shift the orbit of the asteroid, well, this is inevitably going to remove chunks of asteroid, that are now new, smaller asteroids, but if they’re not small enough and they’re headed toward us instead of somewhere else, you could end up with a ring of impacts all the way around the planet, and if this ring happens to occur in the Northern Hemisphere, well, that’s where most of the land masses of our planet happen to be.

Fraser: That’s going to wipe out all life on Earth?

Pamela: No, it’s just going to make most life on Earth sad.

Fraser: Most life! That’s the thing, so again, they call it…remember like Armageddon [missing audio]? But even that wouldn’t do the trick. And, of course, now there’s all this research, in fact, maybe the vast majority of the biological life on Earth is not on the top, the outside, on the crust, but actually is within the crust of the Earth.

Pamela: By mass, but not by complexity. There’s complex life…

Fraser: But it could be complex later. It could evolve out of the ground and take over.

Pamela: And it could take long enough that we‘ll be oil, so it’s all good.

Fraser: Yeah, yeah, and in fact, people could have recycled the elements. Iron would be lying around on the ground again, and the ground bacteria will come back…

Pamela: …billion years in the future that the Sun will kind of have destroyed our planet, but the way that we really do need to worry about 50 billion years…

Fraser: We’ll get there. That’s one of the things I want to talk about, but…because there’s other stuff that can scour stuff off the Earth. Like think about a gamma ray burst.

Pamela: You do have to worry about…now as far as we know, at this point in our orbit around the center of the galaxy, now this can change as we continue to orbit (this is the problem with orbiting is we’re a moving target) is at this point we’re safe. As far as we know there are no nearby giant stars getting ready to go hypernova that have their rotational axes and thus their future gamma ray jets pointed at us. Eta Carinae could potentially be a gamma ray burst. As near as we can tell from looking at its structure, it’s not pointed at us. We’ll be able to see it. We’re close enough that we could have been destroyed, and this is actually a really neat way to destroy life because it basically…so the gamma rays are only going to hit one side of the planet and then the other half of the planet is going to get protected by that first half of the planet, spherical object, three dimensions and all that. So the gamma rays hit one side of the atmosphere, they instantly destroy large amounts of the ozone layer and cause all kinds of neat chemical reactions that cause larger molecules to form in the upper atmosphere. This has the double effect of overall dimming the amount of light that hits the planet, cooling things off, but also allowing ultraviolet through, which is kind of dangerous and kills things. So in the process of destroying our atmosphere, it destroys the ability of plants, the basis of our food chain would be plants, so you end up with dead plants. So it sterilizes half the planet and this becomes a chain reaction working around the planet, and so things that are underground when this occurs, probably OK. If they stay underground, probably OK, but will eventually starve to death. It’s that starving to death part that’s problematic.

Fraser: But then you know [missing audio] returns and life finds a way. OK, so then [missing audio] supernova explosion going off, I guess if it was close enough…?

Pamela: And this is the creepy one is we could actually…people forget about white dwarfs. They’re small, they’re not that bright it’s easy for them to go unnoticed. Now, if you happen to have a white dwarf in a binary system that is fairly close, hidden in gas and dust so it’s fairly obscured, and that white dwarf starts selfishly gravitationally nomming its neighbor, and it exceeds the point at which its electron degeneracy pressure, the pressure of which the electrons are pushing against one another to support that white dwarf star, it could become so massive that the gravitational crush on that star overcomes the electrons pushing the star apart, the electrons are going to go, “OK protons, we’re joining forces and becoming neutrons,” there’s a burst of energy, it collapses down into a neutron star, there’s a supernova in the process, and that could happen nearby, and we just haven’t seen that pair of quietly-considering-self-destruction-suicide-murder-pact stars.

Fraser: So we get this Type II supernova within…

Fraser: Type 1-A. We get a type 1A supernova within…how far? If it’s Alpha Centauri, are we doomed?

Pamela: Alpha Centauri? Yes, totally doomed.

Fraser: Totally doomed…you mean it could destroy the Earth?

Pamela: Yeah, we’re looking at order of kilo-light years on this one.

Fraser: Within 1000s of lightyears, if you get a type 1A supernova it would probably destroy life on Earth.

Pamela: Same way the gamma ray burst did.

Fraser: We’re safe…but for how long? OK, so explosions in space, black holes, so then, OK, so I think what we’re driving at is almost everything that we’re afraid of really just something that we should just personally, humans and life, current life forms should be afraid of. [missing audio] life forms — they don’t care, they’ll evolve out of it and they’ll be a long-forgotten. They might dig up some crater under a seamount, “Oh yeah, that’s where the humans were destroyed, right?”

Pamela: And this is where organizations like the Lifeboat Foundation, which both David Brinna and I are both on the board of, this is where organizations like that are working to collect vast samples of genetic materials and seeds to essentially figure out how do we create a genetic ark that would allow all of the different critters that we wish we knew more about to exist in the future. How do we create that future where black rhinos can exist again? Funding’s not there yet, this is probably good, but I don’t know, black rhinos are kind of awesome.

Fraser: OK, so I think we can throw a bunch of others out, like alien invasion. Again, that’s just us. Invacom, they’ll kill us all, enslave us, take our water…

Pamela: You know, we do have to worry about Death Stars.

Fraser: Death Stars? Oh, right, right, of course!

Pamela: Alderon is not coming back together again.

Fraser: But the amount of energy required…

Fraser: I know, but the amount of energy to actually destroy…

Pamela: Aliens! They got here, didn’t they?

Fraser: Wait a second! Isn’t this backwards? Aren’t I the one who’s supposed to…yes, that’s true, the aliens got here, they’ve somehow brought their death star, and then they shot their super laser and destroyed the Earth. Actually, there’s a fantastic website that somebody actually did the math on what it would take…I forget what. It was ludicrous. No way in the world…

Pamela: Phil Plate’s run the calculations as well. It is ludicrous. We do not have the capacity. It’s doubtful the capacity will ever exist. 10 to the 23rd joules…. Martin is saying down front.

Fraser: So that’s not going to happen, so let’s move on then, I think, to the things that will probably, most likely, and eventually inevitably destroy the Earth. The first one you were sort of jumping at already is our Sun is heating up.

Pamela: Our Sun is heating up, and it is a gradual process, but even before our Sun decides to bloat up to become a red giant star, it’s going to heat up enough that the slight change in temperature of the surface of our planet is going to cause the oceans to evaporate just enough that it creates a runaway greenhouse effect. And the problem is as you get more and more water vapor in the Earth’s atmosphere, it becomes harder and harder for IR radiation, heat to escape the surface of our planet. The hotter it gets, the more water evaporates, the more of an insulating effect it has, eventually we end up with no more water that isn’t in our atmosphere, and when you’re trying to drink it, that’s not where you want it.

Fraser: Right and we talked about how it would take, whatever, six billions years, seven billion years for the Sun to actually turn into…

Pamela: A billion years.

Fraser: Yeah 5 or 6 billion years for the Sun to turn into this red giant and actually [missing audio], but the Sun is heating up, and it’s not long. I mean, you say…

Fraser: Maybe 500 million years on the outside, and, again, there’s a really great book, was it Life and Death of Planet Earth? I don’t remember what it was, that essentially 500 million years ago Earth was really too cold, and the Sun the heating really hadn’t kicked in, so you couldn’t get these complex life forms, and then within this billion-year zone, you get enough heat that the complex life forms can come out and fill our atmosphere with oxygen, and then the Sun’s going to get too hot and it’s all going to go in reverse, and the complex life forms aren’t going to last, and eventually it’s just going to be this parched desert, and all the water and all the carbon dioxide has been pushed up into the atmosphere…

Pamela: …which will cause new chemistries, which will cause us to look more and more like Venus.

Fraser: Yeah. All that water, though, is going. All those hydrogen atoms, just like our helium atoms before — they’re going, right? They’re leaving?

Pamela: Unless they get tied up in molecules.

Fraser: But they’re in the water [missing audio]…

Pamela: Well, this is where carbon monoxide, carbon dioxide…there’s so many molecules, hydrocarbon chains are going to end up forming, sulfuric acid potentially. What’s really scary is when you start looking at the models of how Venus got to be Venus — that’s potentially our future. And Venus — 900 degrees Fahrenheit — not so good to live in!

Fraser: So we’re going to get this heating, and that will kill all the surface life, and maybe that inside life inside has got a few more billion years, right? So what’s next?

Pamela: So the next inevitable death of the planet Earth – inevitable, there’s other ways we could die, but inevitably our Sun is going to end up bloating up into a red giant star, along the way it has mass loss, so while the red giant star will be bigger than the Earth’s current orbit, as the Sun loses mass, our orbit creeps further and further and further out over time, so as the Sun has less mass, our orbit increases, so it’s pulling on us less, it’s just the way orbital mechanics works. It’s kind of convenient because if our current models for mass loss are correct, the Sun doesn’t eat us, it simply fries us.

Fraser: Right. It kills most life on Earth, but still the stuff that’s inside, heated by the internal cooling heat of the Earth is still going to be around.

Pamela: Internal cooling heat of the Earth?

Fraser: Sorry. The stuff, by the internal heat of the cooling Earth, is still going to be around.

Pamela: I think what he’s trying to say is while the surface of the planet is going to be a crispy critter broiled by the Sun, as you dig down, while radioactive decays within our planet will continue to keep the inside of the planet fairly warm, it’s still cooler than the surface.

Fraser: Yeah, and eventually, you know, when the Sun goes away, and the whole environment cools back down again, you’re going to have a slow cooling off [missing audio], but still an environment that organisms can grab energy from.

Pamela: Well, and the thing is, once our Sun is done with its whole being a bloated star phase, it’s going to let go of its atmosphere and become a beautiful nebula, like the Owl Nebula – it’s one of my favorite things to look at — and our Sun is going to leave behind a cooling white dwarf that will continue to feebly cast a very harsh light for a while. So our whole future, well, it’s long stretching before us.

Fraser: But it’s weird to think about that that we, as complex life forms, we don’t have a long time on this planet in the vast scale when you think of how tough life is when you scrape it off radioactive cooling towers, nuclear reactors, you find it in all these places. “Life will find a way,” to quote Jurassic Park, and again, you can imagine… Then you can imagine the life that has been kicked up into space [missing audio] floating around the solar system, landing on Mars.

Pamela: My favorite magazine caption of all time is from Scientific American. It’s an article on asteroid impacts and in fact the impact that killed off all the dinosaurs when it formed the Chicxulub crater in the Yucatan, and one interesting Mayan fact is the sinkholes that have water in them where the northernmost settlements of the Mayan culture are, those are tracing the route of the Chicxulub crater, but anyway, when that crater was formed, a happy little brontosaurus, or a happy big brontosaurus as the case may be, eating leaves, minding its own business on the Yucatan peninsula, or wherever on the planet that part of the planet was, when that asteroid came it melted a large area and sent a shock wave through that flung debris plants, and that brontosaurus at escape velocities into space, and so this magazine caption wrote, “When the asteroid hit, it flung soil, plants and dinosaurs into orbit.” It was awesome!

Fraser: That’s cool. So, yeah, we definitely wiped out humanity a long time ago. Life is still tricky, and still surprising that, even the Sun goes through this phase, now maybe if the math is wrong then maybe the Earth might get consumed by the Sun.

Pamela: And it’s not just the math, we’re pretty sure we’re doing the math right. What we’re not sure about is if we understand mass loss rates correctly yet we’re still understanding that. We don’t have any stars other than our Sun close enough to measure mass loss rates precisely, and since we’re trying to predict what our Sun will do in the future, can’t measure that precisely.

Fraser: So we’ve got this burned-out center of the Earth, orbiting the Sun. Sun is a small white dwarf. Is there any chance that now with all this loss of the Sun that the Earth is somehow going to spiral inward?

Pamela: No. Gravity does not work that way.

Fraser: So it’s going to be spiraling probably outward?

Pamela: Well, once the Sun is happily a white dwarf, it’s no longer undergoing mass loss.

Fraser: But hasn’t it lost a lot of mass?

Pamela: It has, so we’re further out.

Fraser: We will compensate perfectly, yeah.

Pamela: We’ll compensate, and we’re just going to keep orbiting that little sucker.

Fraser: Now what about the interactions between the remaining planets? Is there a chance that you could just [missing audio] the planet for trillions of years that they’re just going to collide?

Pamela: Not that we know of. And the neat thing is when you look at the Nice model for how our solar system got to where it is now, in the past, the planets were in radically different situations, but over time, through the age of the heavy bombardment, Jupiter, Saturn, Uranus and Neptune migrated outward with Jupiter and Saturn passing through different resonances that had the effect of flinging the other two ice giants to further orbits. Now, everything seems to be settled where it is, so unless we get some new resonance forming because somehow we capture another planet, low probability, not going to happen unless monkeys make Shakespeare, I think we’re good.

Fraser: OK. Another star system collides, passes within…

Pamela: Space is empty.

Fraser: I know, but you’ve got a long time. Take a trillion years, so could we have these interactions? It’s still not going to wreck the Earth. It’s just going to fling it out into space.

Pamela: No, it’s just going to put it somewhere else.

Fraser: Right. OK. Black hole.

Pamela: This actually is a non-zero probability, and greater than monkeys creating Shakespeare issue.

Fraser: Is a black hole?

Fraser: OK. OK. I’m intrigued.

Pamela: So we have a couple of different things to worry about: first of all, is the rogue stellar mass black hole. This is a former star that started out probably greater than 10 solar masses. We say probably because, again, mass loss rates, if it loses enough mass, it ends up becoming something other than a black hole. Started out probably greater than 10 solar masses, when it died it ended up collapsing down into a black hole, and during the process of having a supernova explosion, and now that dark sucker is just happily orbiting the center of the Milky Way, and its orbit is perhaps elliptical, causing it to cross our solar system’s orbit the way comets cross our planet’s orbit. There’s nothing about this that makes the black hole a hunter-seeker out to eat us. It’s simply orbital dynamics. If it has an elliptical orbit that crosses our solar system’s orbit, it could sneak up on us, pass through the Oort cloud, and as Oort cloud objects gets eaten, we might see flashes of high energy – might. It’s fairly empty out there, but we’ll start seeing things get their orbits changed, and if we’re unfortunate, we could get nommed by that…

Fraser: Hold on. Hold on. Think of the chances of this stellar mass black hole actually colliding with Earth. It’s most likely to do is just run through the solar system, scatter the planets, and again, we get back to that Earth floating through space, cold and alone, but not destroyed.

Pamela: So it depends on crossing times. This is the neat thing is black holes have great reach. They like to reach out and gravitationally touch other objects, so if that 10 solar mass-ish or greater, so let’s say it’s a large stellar mass black hole, it started out as a huge star, it’s passing through our solar system, it has great reach. Now, if another solar system passes through our solar system, that might be a one solar mass star, everything’s thrown into chaos, but that one solar mass star doesn’t have the gravitational reach that the black hole has, and if the orbits are such that we end up co-orbiting so that it very slowly migrates, it’s that slowly passing black hole with a long duration to gravitationally yank on us, that’s what we have to fear. If it’s moving fast, we’re good, but slow motion…

Fraser: If it’s moving slow and it’s got a long reach, it could pull the Earth in into doomed trajectory.

Fraser: OK. Now, we’re cookin’! Now we got something here! Seriously this is it!

Pamela: …[missing audio] the age of the Universe.

Fraser: We’ve gone through all of these encounters, these situations and we still haven’t found something that could really take out the planet. We got one. I love it! OK! Let’s say though that we luck out, and we don’t get a black hole. Is that possible?

Pamela: That’s the thing is people always talk about some day in the future the black dwarfs will vacuum up the entire Universe, and the Universe will be nothing but one giant… No. No. Gravity doesn’t work that way. So yes, over the future trillions of years before protons decay (we’re going to get to that), black holes will slowly as they gravitationally interact with other objects making their merry way, orbiting through space, they will gradually eat things up, including the photons from the cosmic microwave background (we’ll get to that as well), but they’re not going to eat everything. There’s going to be white dwarfs that escape there’s going to be planets orbiting white dwarfs that escape. It all depends on how dense a region of space you’re in. If you’re in a low-density neighborhood, you’re probably good because the crossing times, the probability of interaction…all of those work out to the protons go first, so you’re inevitably going to be destroyed via some interesting process, it’s just not the black hole.

Fraser: Whoa, whoa…what? Hold on. What interesting process will destroy…? Feel free to offer some suggestions because I’m out. [missing audio] proton decay [missing audio] get smashed into a star…

Pamela: Low probability. Black holes…

Fraser: Gobbled up by a black hole…

Fraser: What else is there? Hit by a jet from a quasar? What’s going to destroy it?

Pamela: So really, we have to worry about being decayed or nommed. Those are really the two fears.

Fraser: Right, so that’s it — black holes. Obviously, we’ve talked about stellar mass black holes, we’ve got the supermassive black hole, so this is the question, right? We’ve got these planets orbiting their stars, which are orbiting the Milky Way, and this whole collection is orbiting this supermassive black hole at the center of the Milky Way. Will everything eventually make its way into that supermassive black hole?

Pamela: No, but what’s interesting is in about 5 to 6 billion years, depending on whose models you read, we’re going to combine with the Andromeda galaxy to, depending on whose paper you read, either form Milkomedra, Milkdromeda, which is easier to say

Fraser: Yeah, I like Milkdromeda.

Pamela: Yeah, and there’s actually…I got to narrate my second planetarium show, but my first one, that I was really excited about because it’s all science, this is one of the things they talked about, called cosmic castaways (follow me on Astronomy Cast, which hopefully you already will, and when it hits the internets we will let you know. I’ll go to Youngstown State University, you can watch it). Anyway in about 5 to 6 billion years we’re going to combine with the Andromeda galaxy to form an even larger galaxy that will no longer be spiral in structure. Eventually, our central supermassive black hole and their supermassive black hole are probably going to merge into an even more supermassive black hole. Now, over the course of history, or the future of our Universe, as the case may be, we’re eventually going to also combine with Triangulum, with magellenic clouds, with all of the other galaxies that are part of our Local Group. We’re working our way towards our nearest supercluster, and as the Universe expands, that’s eventually going to become the entirety of our Universe. So we will become part of one giant galaxy that used to be the Local Group, and we’re going to be part of one supercluster, and everything else will have drifted across the observable Universe’s horizon.

Fraser: Will this giant elliptical galaxy destroy the Earth?

Fraser: OK. Same problem, right? Nommed, or…OK so fine. So obviously the math is aweome [missing audio] in space and the Universe.

Pamela: So stellar collisions are possible, black hole nomming is possible, getting somehow — we don’t think from the current models — sucked into a supermassive black hole. Again, models say no, but it’s possible.

Fraser: Some kind of three-body interaction that fires us on an orbit that [missing audio]…

Fraser: OK. Great! But then maybe by all likelihood, or maybe, we don’t know yet, we’ll miss all that, then none of these potential collisions will happen with the Earth, and it will last until when?

Pamela: This is where we start looking at long time. Take a one, add 38 zeros: 10 to the 38th seconds into the future. This is where we start looking at potential proton decay. Now, the problem is we keep trying to detect proton decay because, well, we know from supernovae that galaxies like ours should have one supernova explosion roughly every 100 years. This means if you look at 100 galaxies for one year, one of them will have a supernova explosion. If you look at 100 x 365 in one night, you’ll probably see one supernova. That works. So in theory if we’re looking for proton decay, take a large vat of water, make it large enough so that it has 10 to the 38th protons in it, in theory we should watch one of these suckers decay and they refuse to, so our estimates of how long it takes protons to decay keep evolving.

Fraser: If they even decay.

Pamela: And this is the problem: there really is no good particle physics underlying theory. This is one of those great frustrations of scientists. We desperately want that set of equations that describes everything, so that we can in our computers, from first principles, F=MA, build the Universe, and particle physics refuses to behave, so until we have a model that works and explains why we get the masses, why we get the spin, why we get all of the different characteristics that we find in particles, we can’t figure out how long it will be until (and if) protons decay.

Fraser: And so what you’re telling me is that the Earth is unkillable.

Pamela: Only if protons refuse to decay.

Fraser: Yeah. If it turns out that protons do not decay, and the Earth’s protons will last forever…

Pamela: But, so if the Earth is going to last forever, then eventually it will get nommed by something because the crossing times allow…

Fraser: It’s just a matter of time

Fraser: But still, I don’t think the Mayans predicted that.

Pamela: But one of the really awesome things about how all of this works is right now the reason supermassive black holes aren’t happily sitting out there evaporating is because the cosmic microwave background, that echo of light from when atoms first formed and electrons and protons and atomic nuclei stopped all interacting together – that moment the cosmic microwave background was formed, light was let loose and we’re still seeing that echo of light, and that echo of light is sufficient to counteract a supermassive black hole — in fact, any stellar mass large black hole from being able to evaporate. But over time as the Universe continues to expand, that radiation is getting to longer and longer wavelengths, lower and lower energies, and eventually that light’s going to get spread out and eaten up. At that point, the supermassive black holes are going to be able to start evaporating, turning our Universe into this basically smooth continuum of energy. Then the protons start decaying into energy.

Fraser: If they decay.

Pamela: If they decay.

Fraser: Right. Otherwise it’s Earth and this smooth energy field — this expanding, accelerating Universe.

Pamela: But, you know, in that Universe eventually black holes do get to eat everything. So if the black holes do get to eat everything, then we get eaten by the black hole, and the black hole evaporates, and we have a smooth continuum of energy.
Whoa. OK. I get it. Infinite time, and everything is eventually eaten by a black hole, and all those black holes will eventually evaporate. Either way… Well, thank you very much, Pamela.

Fraser: Alright!
[applause]

This transcript is not an exact match to the audio file. It has been edited for clarity.


ROGUE planet heading towards Earth, shock theory suggests

Last month, a team from the University of Arizona has revealed the gravitational pull of a Mars-sized planet may be slightly altering the objects’ trajectory through space.

The orbit of the objects – known as Kuiper Belt objects (KBOs) as they are in the circumstellar disc full of icy asteroids, comets and dwarf planets which encompasses the solar system – is off by a huge eight degrees.

Now, conspiracy theorists believe the new planet could actually be rogue, and heading inwards towards the sun.

Related articles

In a video uploaded by popular YouTune channel SecureTeam10, the narrator says that the planet could be set to travel through the solar system, bringing with it all kinds of mayhem.

The narrator of the video says: “There is a core group of people out there that believe that there is a rogue planet that is going to make its way through the solar system, passing by Earth and causing complete devastation and panic and it is said that this does this every 50-100,000 years.”


“Rogue Stars from Another Galaxy Racing Towards Milky Way’s Center” –The Gaia Mission

“Rather than flying away from the Galactic center, most of the high-velocity stars we spotted seem to be racing towards it,” says Tommaso Marchetti who used an artificial neural network, which is software designed to mimic how our brain works to helps Gaia catch speeding stars. “These could be stars from another galaxy, zooming right through the Milky Way.”

A team of astronomers using the latest set of data from ESA’s Gaia mission to look for high-velocity stars being kicked out of the Milky Way were surprised to find stars instead sprinting inwards — perhaps from another galaxy. The study is published in the journal Monthly Notices of the Royal Astronomical Society.

Stars circle around our galaxy at hundreds of kilometers per second, and their motions contain a wealth of information about the past history of the Galaxy. The fastest class of these stars are called hypervelocity stars, which are thought to start their life near the Galactic center, later to be flung towards the edge of the Milky Way via interactions with the black hole at its center.

Only a small number of hypervelocity stars have ever been discovered, and Gaia’s recently published second data release provides a unique opportunity to look for more of them.

“Of the seven million Gaia stars with full 3D velocity measurements, we found twenty that could be travelling fast enough to eventually escape from the Milky Way,” explains Elena Maria Rossi, one of the authors of the new study, based at Leiden University, in the Netherlands.

It is possible that these intergalactic interlopers come from the Large Magellanic Cloud, a relatively small galaxy orbiting the Milky Way, or they may originate from a galaxy even further afield. If that is the case, they carry the imprint of their site of origin, and studying them at much closer distances than their parent galaxy could provide unprecedented information on the nature of stars in another galaxy — similar in a way to studying Martian material brought to our planet by meteorites.

“Stars can be accelerated to high velocities when they interact with a supermassive black hole,” Elena explains. “So the presence of these stars might be a sign of such black holes in nearby galaxies. But the stars may also have once been part of a binary system, flung towards the Milky Way when their companion star exploded as a supernova. Either way, studying them could tell us more about these kinds of processes in nearby galaxies.”

An alternative explanation is that the newly identified sprinting stars could be native to our Galaxy’s halo, accelerated and pushed inwards through interactions with one of the dwarf galaxies that fell towards the Milky Way during its build-up history. Additional information about the age and composition of the stars could help the astronomers clarify their origin.

New data will help to nail down the nature and origin of these stars with more certainty, and the team will use ground-based telescopes to find out more about them. At least two more Gaia data releases are planned in the 2020s, and each will provide both more precise and new information on a larger set of stars.

“We eventually expect full 3D velocity measurements for up to 150 million stars,” explains co-author Anthony Brown, chair of the Gaia Data Processing and Analysis Consortium Executive. “This will help find hundreds or thousands of hypervelocity stars, understand their origin in much more detail, and use them to investigate the Galactic centre environment as well as the history of our Galaxy,” he adds.

“This exciting result shows that Gaia is a true discovery machine, providing the ground for completely unexpected discoveries about our Galaxy,” concludes Timo Prusti, Gaia project scientist at ESA.


A golden age of astrophotography, in your backyard

To hear Tim Frazier tell it, the biggest show of the summer might have been the Perseid meteor shower that lights the night sky from July to August. "At night, looking up from a clear place like this, you can see up to 120 meteors an hour," he said.

Though the retired photography professor's work sits in the collections of New York's Museum of Modern Art and the Art Institute of Chicago, his passion has always been astronomy.

"Well, it's the oldest science," he said, "because the only thing that had to happen was people look up and go, 'I wonder &hellip'"

A view of the Andromeda galaxy (Messier 31), 2.5 million light-years from Earth, taken by photographer Tim Frazier. Tim Frazier

Correspondent Serena Altschul asked, "At this point in your life, if you had to choose one of these loves &ndash astronomy or photography and your love for art &ndash which way would you go?"

"Oh, I don't know. I don't know," he laughed. "That's really hard!"

"They are. And the thing is, I think through appreciation of art and aesthetics, it makes me thoroughly enjoy what I see through the telescope more, because you're seeing a real world that is so unbelievably complex and beautiful."

Space & Astronomy

We are in something of a golden age of astrophotography. Cheaper technology (from high-powered telescopes, to computer programs to process terabytes of data) has made it easier for amateurs to capture out-of-this-world images, like this:

Jordan Ragsdale

Boise, Idaho astrophotographer Jordan Ragsdale lets his telescope and camera run for hours, often over multiple nights, while filtering out light pollution, all to create a single useable shot.

"Every night you're out, you run the chances of discovering a new planet potentially, discovering a new comet, a new asteroid, things like that," Ragsdale said. "There's been even some amateurs when they're doing videos of Jupiter and Saturn [who] will catch collisions of asteroids into those planets.

"All the professional observatories, they don't have cameras on every planet, every speck of the sky at all times of the day. So, there's a lot of discovery potential nowadays, with all the new technologies that amateurs have access to, [to] find planets on other stars from their backyard, which is pretty amazing!"

With his telescope, camera equipment and computer software, Jordan Ragsdale can track objects through the night sky, capturing stunning time lapse or composite images and video. CBS News

Still, for casual stargazers in many parts of the country, the heavens have never been further away. Frazier said, "Eighty percent of Americans can't see the Milky Way from where they live. And I know when I was growing up, I just walked in my backyard and there it was. I grew up in Nashville, and when I went back recently, there's no way you can see that now. I mean, the light pollution's unbelievable."

Central Idaho, where Frazier lives now, is rich with abundant natural resources, from the Salmon River to the Sawtooth Mountains. But its greatest resource might be its night skies, some of the darkest in the country.

"We have very clear air, and relatively stable air," said Frazier. "And that makes the viewing just particularly wonderful, because the stars can be so sharp and clear."

To protect those skies, the towns of Ketchum, Sun Valley, Stanley and others regulate outdoor lighting as part of the Central Idaho Dark Sky Reserve, one of only 16 such territories around the world.

But there is a growing threat to our dark skies: satellites. Already there are over 2,000 orbiting the earth. And billionaire Elon Musk's company, SpaceX, wants to launch some 30,000 more as part of Starlink &ndash the company's ambitious plan to offer internet to the world.

This summer, thousands signed a petition saying Starlink satellites could pose an existential threat to astronomy itself.

Being able to spot objects orbiting near the Earth is of vital importance to scientists, because when a meteorite hits our planet, it can have real-world consequences.

In 2013, a meteor the size of a six-story house exploded over the eastern Russian town of Chelyabinsk, sending hundreds to the hospital.

Meteors, said professor Meenakshi Wadhwa, director of the School of Earth and Space Exploration at Arizona State University," have shaped the course of life on our planet. We have very good evidence of course now that 65 million years ago there was a huge impact by a large meteorite, probably six miles across, which basically led to the extinction of something like 70% of all species on Earth, including the dinosaurs. And that's what made it possible for, you know, mammals to flourish and for us humans to be here ultimately.

"Everything that we know and understand about how our planet formed, how the solar system formed, how life might have originated on our planet, all that comes from these rocks," said Wadhwa.

So, maybe preserving our ability to see the night sky isn't just about star-gazing or shooting stars, or even astronomy, but something deeper and more fundamental &ndash something to consider the next time you find yourself looking up and see no stars at all.

"It's very disruptive," said Frazier. "And it's disruptive for animals like us."

"We need the dark?" asked Altschul.

"Just like we need the light?"


For more info:


Story produced by Anthony Laudato. Editors: Joe Frandino and Mike Levine.


The age of the universe

Looking out from our planet at the vast array of stars, humans have always asked questions central to our origin: How did all of this come to be? Has it always existed? If not, how and when did it begin?

How can we determine the history of something so complex when we were not around to witness its birth?

Scientists have used several methods: checking the age of the oldest objects in the universe, determining the expansion rate of the universe to trace backward in time, and using measurements of the cosmic microwave background to figure out the initial conditions of the universe and its evolution.

Hubble and an expanding universe

In the early 1900s, there was no such concept of the age of the universe, says Stanford University associate professor Chao-Lin Kuo of SLAC National Accelerator Laboratory. &ldquoPhilosophers and physicists thought the universe had no beginning and no end.&rdquo

Then in the 1920s, mathematician Alexander Friedmann predicted an expanding universe. Edwin Hubble confirmed this when he discovered that many galaxies were moving away from our own at high speeds. Hubble measured several of these galaxies and in 1929 published a paper stating the universe is getting bigger.

Scientists then realized that they could wind this expansion back in time to a point when it all began. &ldquoSo it was not until Friedmann and Hubble that the concept of a birth of the universe started,&rdquo Kuo says.

Tracing the expansion of the universe back in time is called finding its &ldquodynamical age,&rdquo says Nobel Laureate Adam Riess, professor of astronomy and physics at Johns Hopkins University.

&ldquoWe know the universe is expanding, and we think we understand the expansion history,&rdquo he says. &ldquoSo like a movie, you can run it backwards until everything is on top of everything in the big bang.&rdquo

The expansion rate of the universe is known as the Hubble constant.

The Hubble puzzle

The Hubble constant has not been easy to measure, and the number has changed several times since the 1930s, Kuo says.

One way to check the Hubble constant is to compare its prediction for the age of the universe with the age of the oldest objects we can see. At the very least, the universe should be older than the objects it contains.

Scientists can estimate the age of very old stars that have burned out&mdashcalled white dwarfs&mdashby determining how long they have been cooling. Scientists can also estimate the age of globular clusters, large clusters of old stars that formed at roughly the same time.

They have estimated the oldest objects to be between 12 billion and 13 billion years old.

In the 1990s, scientists were puzzled when they found that their estimate of the age of the universe&mdashbased on their measurement of the Hubble constant&mdashwas several billion years younger than the age of these oldest stars.

However, in 1998, Riess and colleagues Saul Perlmutter of Lawrence Berkeley National Laboratory and Brian Schmidt of the Australian National Lab found the root of the problem: The universe wasn&rsquot expanding at a steady rate. It was accelerating.

They figured this out by observing a type of supernova, the explosion of a star at the end of its life. Type 1a supernovae explode with uniform brightness, and light travels at a constant speed. By observing several different Type 1a supernovae, the scientists were able to calculate their distance from the Earth and how long the light took to get here.

&ldquoSupernovae are used to determine how fast the universe is expanding around us,&rdquo Riess says. &ldquoAnd by looking at very distant supernovae that exploded in the past and whose light has taken a long time to reach us, we can also see how the expansion rate has recently been changing.&rdquo

Using this method, scientists have estimated the age of the universe to be around 13.3 billion years.

Recipe for the universe

Another way to estimate the age of the universe is by using the cosmic microwave background, radiation left over from just after the big bang that extends in every direction.

&ldquoThe CMB tells you the initial conditions and the recipe of the early universe&mdashwhat kinds of stuff it had in it,&rdquo Riess says. &ldquoAnd if we understand that well enough, in principle, we can predict how fast the universe made that stuff with those initial conditions and how the universe would expand at different points in the future.&rdquo

Using NASA&rsquos Wilkinson Microwave Anisotropy Probe, scientists created a detailed map of the minute temperature fluctuations in the CMB. They then compared the fluctuation pattern with different theoretical models of the universe that predict patterns of CMB. In 2003 they found a match.

&ldquoUsing these comparisons, we have been able to figure out the shape of the universe, the density of the universe and its components,&rdquo Kuo says. WMAP found that ordinary matter makes up about 4 percent of the universe dark matter is about 23 percent and the remaining 73 percent is dark energy. Using the WMAP data, scientists estimated the age of the universe to be 13.772 billion years, plus or minus 59 million years.

In 2013, the European Space Agency&rsquos Planck space telescope created an even more detailed map of the CMB temperature fluctuations and estimated the universe to be 13.82 billion years old, plus or minus 50 million years&mdashslightly older than WMAP&rsquos estimate. Planck also made more detailed measurements of the components of the universe and found slightly less dark energy (around 68 percent) and slightly more dark matter (around 27 percent).

New puzzles

Even with these extremely precise measurements, scientists still have puzzles to solve. The measured current expansion rate of the universe tends to be about 5 percent higher than what is predicted from the CMB, and scientists are not sure why, Riess says.

&ldquoIt could be a sign that we do not totally understand the physics of the universe, or it could be an error in either of the two measurements,&rdquo Riess says.

&ldquoIt is a sign of tremendous progress in cosmology that we get upset and worried about a 5 percent difference, whereas 15 or 20 years ago, measurements of the expansion rate could differ by a factor of two.&rdquo

There is also much left to understand about dark matter and dark energy, which appear to make up about 95 percent of the universe. &ldquoOur best chance to understand the nature of these unknown dark components is by making these kinds of precise measurements and looking for small disagreements or a loose thread that we can pull on to see if the sweater unravels.&rdquo