Astronomy

How “fast” do astronomical events occur?

How “fast” do astronomical events occur?

I've seen quite a few news about astronomy but I'm not deep into knowing how it works or how people observe it. It got me thinking: if I want to watch a supernova for example, how long will I have to look for it to watch the whole "event"? Or events like NASA "seeing something coming out of a black hole", were they "looking" at the blackhole when something came out really quickly or did they observe it for months? Or maybe the birth of a blackhole?

Now, I do know black holes that quite a few trillion of years to vanish, I'm just curious how much time does it take for astronomers to observe such events.


A supernova (and many other interesting events) starts abruptly -- a flash of neutrinos lasting just a fraction of a second, but then different aspects of the event play out over minutes, days, hours or years. The astronomy community has for some years been developing increasingly sophisticates ways to deal with such events early on. Instruments with a very wide field of view (gravitational observatories, neutrino observatories, gamma ray detectors on satellites) detect the events initially and bring first networks of robotic telescopes and then humans and still larger telescopes into the loop to try and get as much information as possible about the violent and fast developing early stages. See for example http://growth.caltech.edu/

Other things are slower. The "something coming out of a black hole" (not really that, just something coming from very close to a black hole) event takes a long time, this was just the first occasion when they'd observed that black hole with the right instrument.


In our galaxy, supernovae visible from Earth are very rare events, so if you wait for astronomers to raise the alarm when they see the next one you might have to wait hundreds of years. The prospects of seeing one in faraway galaxies are much better, but even so they are not everyday events. The chances of seeing one from the very beginning when the star collapses and explodes are almost non-existent because when they occur, they have to reach considerable brightness to become noticeable from Earth. However, searching for supernovae is something a well-equipped amateur can do, but it requires a lot of patience. As for the energetic particle beams that some black holes send out, they don't arise from within the black hole itself but from the matter in the accretion disc which is accelerated by the poles of the black hole's magnetic field. As this process continues for many years, you don't need to react so rapidly as a supernova discoverer, but you would need some very high tech equipment to observe and photograph it (the particle beams eject large amounts of matter which form large swirls, sometimes light years in length, from both poles of the black hole, and need a radio telescope to image them).


As described in other answers, most astronomical events vary over rather long time scales. Even a supernova, which starts suddenly, has a subsequent light curve that peaks, then decays usually over many months. However, there are some shorter events.

In the recent LIGO gravitational wave observations, the final stage inspiral and merger of binary black holes or neutron stars generates a detectable GW signal for less than a second.

Other shorter term astronomical observations occur within the Solar system. Of course, the Sun and planets move across the sky over the year, and the Moon changes its phase continuously, repeating about every month. Occasional Solar and Lunar eclipses occur over a time scale of hours, with totality lasting only a few minutes for a Solar eclipse. Similiar time frames apply to other Solar system transits. Occultations, where a solar system object passes in front of a star, are nearly instantaneous for a visual observer. Meteor trails in the atmosphere are common, and are rarely visible for more than a few seconds.


The universe is rather robust in that if physics allows a particular situation, there will usually be some place or time in the universe where that situation will occur. Thus any timescales that are allowed by physics, the universe will have astrophysical phenomena that occur on those timescales.

That's a long way of providing the answer "as fast as can be and as slow as can be, and everything in between."


The answer is that some phenomenas are incredibly fast. Others take billions or trillions of years (or more). But, most observed events don't just occur one time. So we can watch for longer events many times, and observe "snapshots" of many different times during the process, and interpolate to get then process as a whole.


Your question strikes me as being more about humanity than astronomy. We define what is interesting to us: there is no physical law as to what "interesting" is.

The "interesting" part of a supernova might be a couple of months (when it's at its brightest), however, if we could predict when a star was within ten years of becoming a supernova, that would increase the window of "interesting".

The sun has been observed by humans for as long as humans have existed. We still find it interesting. We now know much more about it than when humans first appeared on Earth.

In short, the length of an interesting event is entirely up to us, and each type of interesting event will have its own typical length. It could be milliseconds to millennia.


How &ldquofast&rdquo do astronomical events occur? - Astronomy

Fall 2016 or Spring 2017, Time / Day TBD

01 - January 20: Introduction: Why is ethics important for science? - pdf

  1. Reading "The Belmont Report" (pdf)
  2. Reading "Scientific Misconduct" (pdf)
  3. Reading "Study highlights ethical ambiguity in physics" (pdf)
  4. Optional: Lon Fuller's "The case of the speluncean explorers" (pdf)

02 - January 27: Professional Codes -

  1. Homework:
    • Read NAS "On being a scientist" (pg. 3-26 in the pdf) and "Ethics & Values" from the American Physical Society.
    • Make sure to read the case studies in "On being a scientist". Which ones can be converted into an astronomy case study?
    • Are these documents useful? If you had to improve on these documents, what would you do? Be prepared to discuss your perspective in class.
  2. Reading: The National Academies "On Being a Scientist (pdf, link)
  3. Reading: The American Physical Society guidelines (pdf, link).
  1. Homework:
    • Study the bubble fusion example and be prepared to discuss the following in class: How many violations of APS guidelines can you identify? Compare issues and events to the document "US Federal Policies on Research Misconduct".
    • Writing Assignment: Comment on RM=PF^2 in a concise 0.5-2.0 pgs "Letter to Editor" style. For example, imagine that you read in a newspaper RM=PF^2, how would you respond to it in a letter to the editor? Should RM specify other undesirable behaviour? Why or why not? (Hint: Consider Ch. 1 of the Sigma Xi article).
    • As always, bring a current science ethics news item (if you find one) for class discussion.
  2. The Bubble Fusion Scandal.
    • Early Doubts (pdf1, pdf2, pdf3).
    • Report in Science (pdf).
    • Timeline (pdf).
    • Punishment (pdf).
    • Original Research Manuscripts (pdf1, pdf2, pdf3).
    • Additional info available by searching the web (Science, Nature, New York Times, etc.)
  3. "U.S. Federal Policy on Research Misconduct" (pdf, link)
  4. Read: Science Fraud (pdf).
  5. Read: Punishments fit the Crime? (pdf).
  6. Read: Chapter 1, Sigma Xi document (pdf).
  7. Scan: "A fraud that shook the world of science (pdf).
  8. Scan: The Hendrik Schoen misconduct report (pdf).
  9. Compare & Contrast against the NFL code of conduct (pdf, link).
  10. Scan: Loui "Seven ways to plagiarize" (pdf).
  11. Scan: Rhoads "Responsible Conduct of Research" (pdf)

04 - February 10: Class Presentations

  1. Present your opinion letter on the definition of research misconduct
  2. Present your case studies.
    • Create an astronomy data case study to illustrate fabrication and/or falsification of research results (base it on astronomical data or theory), or plagiarism.
    • If you wish, the project may be disemminated on the course web site. Use your imagination or consider real-life events.
  1. We will finish Class Presentations
  2. Read Conflict of Interest material.
  3. Reading: NASA Peer Review COI Agreement (pdf)
  4. University of California (point #6) (pdf)
  5. Hasselmo "Individual & Institutional Conflict of Interest" (pdf)
  6. COI when professional and personal beliefs intersect: The Gaskell Case (NYT Article, Elitzur Deposition, Gaskell Writing)
  1. Homework: What is an author? What are the criteria for first authorship and coauthorship in astronomy? Who decides?
  2. Reading: ApJ Policy (pdf)
  3. Scan: Coauthorship in Physics (pdf)
  4. Scan: Comparison of Disciplines (pdf)
  5. Scan: Council of Science Editors White paper (pdf, link)
  6. Scan: CSE Opinions (pdf, link)

07 cont'd - March 3: Authorship - Continued

  1. Class Assignment: Devise a set of questions and authorship scoring system, to be used to interview a postdoc on their author list on a paper they have prepared.
  2. Compare the author list created from the interview to the author list originally given by the lead author. Where are there differences and why did they occur?
  3. Reading: Quantifying co-author contributions (Hunt 1991)
  1. Homework: Define research data and ownership. Do astronomical data have characteristics that make them susceptible to ethical dilemmas that are different or more numerous compared to other disciplines?
  2. Reading: OMB Definition (link, search for "research data")
  3. Reading: PHS definition of the research record (link)
  4. Reading: Explore the different possibilities here (pdf)
  5. Reading: Astronomy examples (FERMI, CoRoT, Phil Plait essay, Steve Beckwith essay)
  1. Reading: Galileo (pdf)
  2. Reading: Ledford article on collaborations (pdf)
  3. Reading: Kennedy on Bayh-Doyle (pdf)
  4. Reading: Thursby squared on Bayh-Doyle (pdf)
  5. Reading: How many patents are managed by UC? (pdf)
  6. Reading: AAAS Report Sections 1 (pg. 11), 1.3, 1.3.1 (pgs. 14-15) (pdf)
  7. Homework Due: Present the pros and cons of various possible software licenses. In your view, what would be an ideal combination of terms for the original software that you write during the course of your scientific research?
  1. Reading: Nature's Guide for Mentors (pdf1, pdf2)
  2. Reading: Gonzalez et al. on mentoring (pdf)
  3. Reading: Postdocs (pdf)
  4. Reading: Mentoring graduate students (pdf)
  5. Reading: "Truth and Consequences" (pdf1, pdf2)
  6. Resources: UC Policies on Whistleblowing (pdf1, link)
  7. Resources: ORI on Whistleblowing (link)

11 - April 7: Environmental Ethics - pdf

  1. Homework: What ethical principles guide the Outer Space Treaty (link)?
  2. Look through: Planetary Protection (link), Mars contamination, (pdf, search for term "ethical")
  3. Homework: Should the RMO have been removed? (AAS email, Hanford link, search for the term "observatory" in the following pdf1, pdf2)
  4. Reading: John Lacy on the environmental impact of SOFIA (ppt, pdf)
  5. Read: The Wekiu Bug: List a number of ways that an observatory impacts the environment (pdf)
  6. Expert Material: Philosopher Andrew Light reading (pdf) ,and "The dignity of living beings with regard to plants" (pdf)

12 - April 14: Guest Lecture -

  1. Homework: Think about your answer to the following - "Weapons and intelligence gathering are essential for safeguarding the citizens of a country against attacks. Under what circumstances might you work for the government or industry where your role includes developing weapons or other types of support for national defense?
  2. Scan: Office of Naval Research Education Opportunities (link), UC e-mail (txt)
  3. Writer Michael Atiyah states that scientists such as Edward Teller encourage the arms race by "constantly developing more advanced technology". Who is Edward Teller? What impact did he have on the scientific research at the University of California? As you read about him, think about the types of ethical dilemmas he may have thought about and the ways in which he acted. Do you agree with the Atiyah statement?

14 - April 28:Guest Lecture -

ADDITIONAL LECTURES

Intelligent Design - Guest Lecture: Glenn Branch (Deputy Director, National Center for Science Education). (lecture slides pdf)

  1. Reading: Glenn Branch, "Creationism, intelligent design, and evolution," pp.
    147-156, vol. 1, Battleground: Schools, ed. Sandra Mathison and E. Wayne
    Ross, Westport CT: Greenwood Press, 2007. (pdf)
  2. Reading: Barbara Forrest and Glenn Branch, "Wedging creationism into the
    academy," Academe 2005 Jan/Feb (link, pdf)
  3. Find the astronomy-related topics in http://www.answersingenesis.org and http://www.reasons.org

Ethical dilemmas in military research & technology transfer - (lecture slides pdf) -- Guest Lecture: Prof. Chris McKee

  1. Homework - think about answers to the following questions:
    • Intelligence gathering is essential in safeguarding the country from terrorist attacks. Should astronomers become involved in developing more powerful spy satellites to assist in this effort?
    • A number of countries have nuclear weapons, and more are developing them.
      Until such weapons can be brought under international control, what policy should
      the US adopt toward carrying out nuclear weapons research?
  2. Scan: Office of Naval Research Faculty Sabbaticals (pdf), UC e-mail (txt)
  3. Writer Michael Atiyah states that scientists such as Edward Teller encourage the arms race by "constantly developing more advanced technology". Who is Edward Teller? What impact did he have on the scientific research at the University of California? As you read about him, think about the types of ethical dilemmas he may have thought about and the ways in which he acted. Do you agree with the Atiyah statement? What codes of ethics are applicable?

Advocacy for Big Science: The role of scientists in setting national priorities - Guest Lecture: Prof. Steve Beckwith (Vice President for Research and Graduate Studies, University of California)

  1. Reading: Is the role of kids significant? Why? (pdf, link)
  2. What ethical considerations led to the cancellation of a Hubble servicing mission? What ethical considerations led astronomers and other to advocate a reversal of this decision?
  3. Reading: A turning point for Hubble (pdf)
  4. Reading: Zimmerman's "Universe in a Mirror", Chapter 3 (pdf)
    • What is a "buy-in" and what is the "Black Art"? Are they unethical?

Science and Ethical Dilemmas in the Blogosphere - Franck Marchis (SETI Insttitute) pdf

Diversity & Inclusion- Guest Lecturers: Dr. Maryam Modjaz and Vice Chancellor Gibor Basri (UC Berkeley) (lecture slides pdf1, pdf2)


Related Items

1 May 26: "Blood Moon" and Total Lunar Eclipse

May 26 is a special night for astronomy fans. It not only marks the full Blood Moon, but it also marks the date of a total lunar eclipse.

First, let’s explain the full moon. On April 26, the moon is not only full, but it’s also relatively close to Earth. According to The Farmer’s Almanac, the moon will be just 222,116 miles away from Earth. In fact it’ll be so close that those who live near the coasts could see a “dramatically large range of high and low ocean tides around this time.” This full moon, The Sky explained, was typically known to early Native American tribes as the Flower Moon because it occurs just as the flowers begin to bloom in spring. This year is a little different, however, and that’s because of the lunar eclipse.

On the night of May 26, the moon will pass through the Earth’s shadow, which will make the moon appear to turn red—hence why this is also referred to as a Blood Moon. According to The Sky, the eclipse will be visible throughout the Pacific Ocean and parts of eastern Asia, Australia, and western North America.

2 June 10: “Ring of Fire” Solar Eclipse

If you thought the blood moon was cool, wait until you hear about the “ring of fire.” On June 10, those living or visiting Canada, Greenland, or Russia will be lucky enough to look up and see the annular solar eclipse, which occurs when the moon is positioned too far away from Earth to completely cover the sun, explains National Geographic. Because of this, the moon appears to be surrounded by a “ring of fire” as the sun pokes out from behind it. According to National Geographic, “the full eclipse path starts at 9:49 UT over Northern Canada and ends in Russia at 11:33 UT.”

Don’t worry if you’re not directly in its path: A partial eclipse will still be visible in the Northeastern U.S. and Europe. (Just remember to get your solar eclipse glasses early.)

3 June 21: Summer Solstice

While no flashy show occurs in the night sky on June 21, it’s still a significant annual astrological event. On this June date, The Northern Hemisphere celebrates the summer solstice, which marks the longest day of the year and the first day of summer. The summer solstice is often a day filled with celebrations, including a huge sunrise-viewing bash at Stonehenge in England.

4 July 12: Venus-Mars Conjunction

On July 12, Venus and Mars will come together overhead and appear to kiss in the night sky (very fitting, considering that in Roman and Greek mythology, Venus and Mars—or Aphrodite and Ares in Greek—were known to be lovers). According to National Geographic, the pair of planets will be so close to Earth that they’ll be visible through simple backyard telescopes and look like an ultra-bright star to the naked eye. The Venus and Mars “collision” will also be joined by a crescent moon, allowing these two planets to appear as the brightest object overhead.

5 August 12 and 13: Perseid Meteor Shower Peaks

The Perseid meteor shower is so big it extends into two whole nights. Each August, the sky above the Northern Hemisphere explodes with meteors overhead as the Earth passes through a cloud of debris left over by the comet Swift–Tuttle. These fiery leftovers make up the Perseid meteor shower, which is predicted to be active from July 17 through August 24, with its peak occurring right around August 12. According to National Geographic, this summertime show can produce up to 60 shooting stars an hour, most of them leaving beautiful, visible trains, making these late summer nights the ideal time to make a wish.

6 August 18: Mars-Mercury Conjunction

Mercury appears to be getting a little jealous of all the attention Venus got from Mars. To make up for it, planet Mars will have its own conjunction with Mercury at sunset on August 18. At that time, the two planets will also appear to touch in the sky. However, this event will be harder to see than others, since it typically occurs close to the setting sun. But you just might catch it if you bring out your telescope and try to find a clear line toward the western horizon.

7 August 22: Blue Moon

It seems fitting that the summer’s epic astrological events will come to a close with a blue moon. According to The Sky, “[T]here are normally only three full moons in each season of the year. But since full moons occur every 29.53 days, occasionally a season will contain four full moons. The extra full moon of the season is known as a blue moon.” It’s a rare astrological event that only happens once every 2.7 years, so it’s a fantastic one to go outside and see. And even though the August 22 moon won’t actually look blue, it’ll still be a stunning sight to behold—a beautifully infrequent event that happens, quite literally, once in a blue moon.


What are equinoxes and solstices?

Equinoxes and solstices are frequently used as anchor points for calendars. For people in the northern hemisphere:

  • Winter solstice is the time in December when the sun reaches its southernmost declination. At this time we have the shortest day. The date is near 21 December.
  • Summer solstice is the time in June when the sun reaches its northernmost declination. At this time we have the longest day. The date is near 21 June.
  • Vernal equinox is the time in March when the sun passes the equator moving from the southern to the northern hemisphere. Day and night have approximately the same length. The date is near 20 March.
  • Autumnal equinox is the time in September when the sun passes the equator moving from the northern to the southern hemisphere. Day and night have approximately the same length. The date is near 22 September.

For people in the southern hemisphere, winter solstice occurs in June, vernal equinox in September, etc.

The astronomical &ldquotropical year&rdquo is frequently defined as the time between, say, two vernal equinoxes, but this is not completely accurate. Currently the time between two vernal equinoxes is slightly greater than the tropical year. The reason is that the earth&rsquos position in its orbit at the time of solstices and equinoxes shifts slightly each year (taking approximately 21,000 years to move all the way around the orbit [1] ). This gradual change, called &ldquoprecession&rdquo, combined with the fact that the earth&rsquos orbit is not completely circular, causes the equinoxes and solstices to shift with respect to each other.

The astronomer&rsquos mean tropical year is really a somewhat artificial average of the period between the time when the sun is in any given position in the sky with respect to the equinoxes and the next time the sun is in the same position.

You can find dates and times for equinoxes and solstices at the US Naval Observatory.


PREDICTABLE ASTRONOMICAL EVENTS

Anyone visiting their local bookstore or public library sees hundreds of books on astronomy. Topics range the full gamut from asteroids colliding with Earth (e.g., extinction of the dinosaurs) to the possibilities of life on other worlds (e.g., exobiology or the Search for Extra-Terrestrial Intelligence a.k.a. SETI). There are yearly almanacs with tables listing positions of the sun, moon, and planets as well as pictorial table top books showing how the planets and galaxies look through the cameras of deep space probes or the Hubble Telescope. If you need to know how to build a telescope or photograph galaxies, the sources are just a short walk or drive away. It won't be too long when all this information becomes accessible to anyone on their personal computer through the World Wide Web for example in just seconds.

This book (more like a handbook) is intended to provide a general appreciation for the rarity of planetary, lunar, and solar configurations in the sky. Unlike many books on astronomy, I have attempted to show the rhythm of the planets and their moons and have provided excellent references in each footnote for those seeking more details. The bibliography also suggest additional reading sources for those interested. There are undoubtedly more examples of interesting and unusual celestial alignments which I encourage you to explore with today's astronomy software. The bottom line is that if you are not motivated to take your telescope or binoculars outside one very cold winter's night, maybe you will if you realize that you won't have a second chance to observe a once-in-a-lifetime Predictable Astronomical Event.

INTRODUCTION

On 20 July 1994, at exactly 25 years to the minute when man first stepped foot on the Moon, a bolt of lightning struck a tree in front of my house while I stood only 30 feet away. At the same time, halfway across the solar system, Comet Shoemaker-Levy 9 was cascading into Jupiter with cataclysmic effects the likes never witnessed before. The coincidences and significance of these milestone events actually have something very much in common. They both belong to a class of phenomena which is not predictable over any useful time frame or dimensional scales. Perhaps chaos and quantum physics may never allow us to control our ultimate environment, however fortunately, at an everyday level of human interaction, we do a pretty good job at predicting most outcomes. Consequently, I was lucky to have survived this chance encounter. The tree's unplanned meeting with several million volts faired as well and Jupiter's gaseous atmospheric belts repaired themselves in the following months.

As an amateur astronomer, I have often wondered why things in nature are beautiful. Philosophers over the millennia have attempted to definite aesthetics but I believe have missed articulating what the essence of this subjective perception of reality is. We appreciate the value of an emerald because of its color, durability and rarity. The question then is whether beauty has to be something tangible or materially valuable.. I believe that beauty holds something much deeper. The importance in our ability to explain and therefore predict an outcome of something we are observing is what makes it beautiful. We take comfort in the familiarity. Beauty then becomes more than just what the eye of the beholder sees. Beauty is one's ability to make sense from all the unpredictable noise we call randomness.

On 8 April 1977, I viewed Mars' occultation of the bright star Mebsuta (2.9 magnitude) in the constellation Gemini. This event was heralded as not only a once-in-a-lifetime occurrence, but one of just a few of this type visible in a millennium. Was this really true and if so why. There are thousands of stars visible to the unaided eye, so surely a planet must occult one frequently. What then is the dynamic relationship each body in the Solar System has with one another and the nearly stationary background stars? Perhaps because statistics associated with celestial mechanics is always changing as the planets' gravity and tidal forces interact in extremely complex ways, the task of documenting orbital commersurability and sygyzy is a useless endeavor. I believe with some patience, one can acquire an appreciation for these inter-dependencies.

The 32 bit personal computer has truly opened the world to endless possibilities. We now have the capability to predict the time, location, and physical aspects of nearly anything we can imagine. As amateur astronomers, we now have a virtual reality time machine that can take us to the far reaches of our solar system at an instant and at an epoch. It is with this in mind that I have attempted to compile a periodical time dependent sequential list and non-periodical list of most commonly known astronomical phenomena that are predictable and observable (without elaborate equipment) from Earth. Many events will require traveling to foreign locales such as witnessing a total solar eclipse. Other's will occur several times over a brief time span but will not return for centuries such as a triple conjunction of Uranus and Neptune. In complying these data, I applied a certain amount of discretion. As with any statistical undertaking, data that marginally fits a specific criterion is open to interpretation and acceptance. For example, just how far in solar elongation can planets be seen when occulted by a very young or old Moon? This depends on the inclination of the ecliptic plane to the horizon. I have made every effort to provide caveats in defining particular events.


February 21

This Israeli company was a finalist in the Google Lunar X Prize, which ended without a winner last year. If Beresheet launches on time, its lander will aim to touch down on the lunar surface in April. Read more about how SpaceIL made it to the launchpad here.

Craig Bailey/Florida Today, via Associated Press

The Star Of Bethlehem And The Magi: Myth Or Reality?

Trying to relate biblical narrative to actual historical events is a complex field of scholarship that attracts interest both from inside and outside academia.

The purpose here is multifaceted, from the believer historian or astronomer who wants to prove that there is a connection, to the nonbeliever who wants to disprove any such thing. In the middle, there are those who want to investigate the historical and, often, the astronomical data in search of phenomena or events that justify a biblical mention. Chief among such events is the appearance, as mentioned in the Gospel of Matthew, of the Star of Bethlehem illuminating the skies to the birth of young Jesus and guiding the Three Wise Men from the East toward his birthplace.

A recent book, The Star of Bethlehem and the Magi, edited by astronomer Peter Barthel and theologian George van Kooten, collects interdisciplinary perspectives from experts on the ancient Near East, the Greco-Roman world, and modern astronomy. The book is the proceedings of an international conference that took place in 2014 at the University of Groningen in the Netherlands.

Largely, the articles are a response to a previous study by astronomer Michael Molnar, published in his 1999 book The Star of Bethlehem: The Legacy of the Magi, where he claims that the star was an actual astronomical event, namely the appearance of Jupiter in conjunction with the sun, the moon, and Saturn in the constellation of Aries — which modern celestial mechanics calculations show occurred on April 17 in the year B.C. 6. According to Molnar, astrologers would interpret such celestial event as a major portent, signaling a sort of royal birth. Couple that with the expectation of a Messiah born from the house of David, and the connection between a celestial event and the actual birth was justified. According to Molnar, the Three Wise Men were actually (Persian? Arabian?) astrologers well-versed in the motion of the skies and, hence, keen to see such powerful astrological sign vindicated in reality.

Barthel and Kooten summarize the results of their conference into four questions: What? (the astronomical phenomena) When? (the chronology of events) How? (the role of astronomy and astrology) Why? (the evangelist's motivation). On the nature of the astronomical phenomena, there was complete agreement with Molnar, qualified agreement and radical disagreement. On the "when," most agreed that Jesus's birth took place between B.C. 7 and B.C. 5. On the "how," there was mostly disagreement as to the intentions and interpretations of astrologers from different regions in the Middle East. One particular difficulty was to justify the appearance of only three "wise men," given the supposed power of the celestial portent. Why not a multitude? As for the "why," Matthew was the one evangelist that considered celestial portents seriously, as they indeed colored his narrative throughout. For example, for the end of time prophecy he would write (Matthew 24:29): "the stars will fall from heaven, and the powers of the heaven will be shaken." Matthew saw prophecy mirrored in the skies.

Although opinions diverge, it seems that celestial events did occur around the birth of Jesus. The problem is that they often do, some more spectacular than others. To the extent that they provide context to a religious narrative, there is a confluence between myth-building and expectation, the skies being the realm of God and thus sacred, sending us signals of what is to come.

If nothing else, the Star of Bethlehem tells us of a time when looking up to the skies in awe and wonder was part of people's lives, something few of us relate to nowadays. Christmas offers the perfect context for us to rekindle this ancient connection.

Marcelo Gleiser is a theoretical physicist and writer — and a professor of natural philosophy, physics and astronomy at Dartmouth College. He is the director of the Institute for Cross-Disciplinary Engagement at Dartmouth, co-founder of 13.7 and an active promoter of science to the general public. His latest book is The Simple Beauty of the Unexpected: A Natural Philosopher's Quest for Trout and the Meaning of Everything. You can keep up with Marcelo on Facebook and Twitter: @mgleiser


Upcoming Astronomical Events

Events that occur during the current year, such as:

  • times of sunrise and sunset and moonrise and moonset (for latitudes 20º to 60º N)
  • Moon phases and other lunar phenomena
  • conjunctions, elongations, etc. of the planets
  • eclipses, transits, occultations by the Moon and by planetary bodies
  • location of the planets, dwarf, and minor planets and returns of periodic comets
  • times of meteor showers
  • the orbital positions of the brighter satellites of both Jupiter and Saturn and
  • predictions of the cycles of many variable stars.

The Sky Month By Month section gives an extensive listing of events throughout the year.


Chiricahua National Monument – May 8, 2021

Our next Chiricahua National Monument Star Party is May 8, 2021 from 7:30 – 9:30 pm. We will have a couple telescopes showings objects on a computer or monitor and a laser guided Walk Around the Night Sky. The Event will be held at Faraway Ranch, about 1 mile inside the park Due to Covid-19, registration is required. Please call the Chiricahua National Monument Visitor Center at 520-824-3560, ext 9302 between 9 am and 4 pm. Participants should dress warmly and wear face coverings, bring a portable chair or blanket to sit on, drinks, snacks, binoculars, and a flashlight with a red filter if possible. For more information, visit the Chiricahua National Monument website at www.nps.gov/chir.


Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 September 23
Triple Sunrise
Credit & Copyright: Jim Hoida

Explanation: Today, the Sun rises due east at the Equinox, a geocentric astronomical event that occurs twice a year. To celebrate, consider this view of the rising Sun and a lovely set of ice halos recorded on a cold winter morning near Green Bay, Wisconsin, USA, planet Earth. Produced by sunlight shining through common atmospheric ice crystals with hexagonal cross-sections, such halos can actually be seen more often than rainbows. The remarkable sunrise picture captures a beautiful assortment of the types most frequently seen, including a sun pillar (center) just above the rising Sun surrounded by a 22 degree halo arc. Completing a triple sunrise illusion, sundogs appear at the far left and far right edges of the 22 degree arc. An upper tangent arc is also just visible at the very top of the view.