# How did VLT's adaptive optics obtain this resolution for Neptune? Is it really working in visible wavelengths?

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This image of Neptune taken with the VLT is really impressive. The resolution is achieved by recent improvements in the adaptive optics.

• Gizmodo: New Super-Crisp Images of Neptune Show How Far Our Telescopes Have Come
• Space.com Telescope Upgrade Produces Stunningly Clear Views of Space

But I don't really understand, is this coming from just one 8 meter mirror, or is this using more than one of the four that make up the VLT? Also, is this really using adaptive optics that work in the visible, including blue wavelengths? Or is this a false-color image? See the excellent answer(s) to Why (actually) aren't ground-based observatories using adaptive optics for visible wavelengths?

It is an image taken with the new narrow field mode of the MUSE instrument using the GALACSI Adaptive optics module on a single (UT4) VLT telescope using laser guide stars.

I am having a great deal of difficulty (e.g. from this press release) in working out at what wavelength(s) this image was taken. I do not believe that the AO system is working at blue wavelengths and therefore the comparison with HST (which certainly does) is somewhat misleading. I think (from ESO's own instrumentation pages) that the MUSE narrow field mode has zero efficiency at blue wavelengths and the description of GALACSI only talks about AO correction approaching diffraction limited images at 650 nm (i.e. red wavelengths).

The captioning to the press release images found here suggest that the shortest wavelengths used in this false-colour image were 550nm and that most of the detail you see is coming from redder wavelengths (600-920nm).

## Supersharp Images from New VLT Adaptive Optics

ESO’s Very Large Telescope (VLT) has achieved first light with a new adaptive optics mode called laser tomography — and has captured remarkably sharp test images of the planet Neptune, star clusters and other objects. The pioneering MUSE instrument in Narrow-Field Mode, working with the GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere. It is now possible to capture images from the ground at visible wavelengths that are sharper than those from the NASA/ESA Hubble Space Telescope. The combination of exquisite image sharpness and the spectroscopic capabilities of MUSE will enable astronomers to study the properties of astronomical objects in much greater detail than was possible before.
The MUSE (Multi Unit Spectroscopic Explorer) instrument on ESO’s Very Large Telescope (VLT) works with an adaptive optics unit called GALACSI. This makes use of the Laser Guide Star Facility, 4LGSF, a subsystem of the Adaptive Optics Facility (AOF). The AOF provides adaptive optics for instruments on the VLTs Unit Telescope 4 (UT4). MUSE was the first instrument to benefit from this new facility and it now has two adaptive optics modes — the Wide Field Mode and the Narrow Field Mode [1].

The MUSE Wide Field Mode coupled to GALACSI in ground-layer mode corrects for the effects of atmospheric turbulence up to one kilometre above the telescope over a comparatively wide field of view. But the new Narrow Field Mode using laser tomography corrects for almost all of the atmospheric turbulence above the telescope to create much sharper images, but over a smaller region of the sky [2].

With this new capability, the 8-metre UT4 reaches the theoretical limit of image sharpness and is no longer limited by atmospheric blur. This is extremely difficult to attain in the visible and gives images comparable in sharpness to those from the NASA/ESA Hubble Space Telescope. It will enable astronomers to study in unprecedented detail fascinating objects such as supermassive black holes at the centres of distant galaxies, jets from young stars, globular clusters, supernovae, planets and their satellites in the Solar System and much more.

Adaptive optics is a technique to compensate for the blurring effect of the Earth’s atmosphere, also known as astronomical seeing, which is a big problem faced by all ground-based telescopes. The same turbulence in the atmosphere that causes stars to twinkle to the naked eye results in blurred images of the Universe for large telescopes. Light from stars and galaxies becomes distorted as it passes through our atmosphere, and astronomers must use clever technology to improve image quality artificially.

To achieve this four brilliant lasers are fixed to UT4 that project columns of intense orange light 30 centimetres in diameter into the sky, stimulating sodium atoms high in the atmosphere and creating artificial Laser Guide Stars. Adaptive optics systems use the light from these “stars” to determine the turbulence in the atmosphere and calculate corrections one thousand times per second, commanding the thin, deformable secondary mirror of UT4 to constantly alter its shape, correcting for the distorted light.

MUSE is not the only instrument to benefit from the Adaptive Optics Facility. Another adaptive optics system, GRAAL, is already in use with the infrared camera HAWK-I. This will be followed in a few years by the powerful new instrument ERIS. Together these major developments in adaptive optics are enhancing the already powerful fleet of ESO telescopes, bringing the Universe into focus.

This new mode also constitutes a major step forward for the ESO’s Extremely Large Telescope , which will need Laser Tomography to reach its science goals. These results on UT4 with the AOF will help to bring ELT’s engineers and scientists closer to implementing similar adaptive optics technology on the 39-metre giant.
Notes

[1] MUSE and GALACSI in Wide-Field Mode already provides a correction over a 1.0-arcminute-wide field of view, with pixels 0.2 by 0.2 arcseconds in size. This new Narrow-Field Mode from GALACSI covers a much smaller 7.5-arcsecond field of view, but with much smaller pixels just 0.025 by 0.025 arcseconds to fully exploit the exquisite resolution.

[2] Atmospheric turbulence varies with altitude some layers cause more degradation to the light beam from stars than others. The complex adaptive optics technique of Laser Tomography aims to correct mainly the turbulence of these atmospheric layers. A set of pre-defined layers are selected for the MUSE/GALACSI Narrow Field Mode at 0 km (ground layer always an important contributor), 3, 9 and 14 km altitude. The correction algorithm is then optimised for these layers to enable astronomers to reach an image quality almost as good as with a natural guide star and matching the theoretical limit of the telescope.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 15 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

## How did VLT's adaptive optics obtain this resolution for Neptune? Is it really working in visible wavelengths? - Astronomy

Technology has helped us go past what would have been though of as possible with similar optics equipment 50 years ago. For the most part, optical mirrors and lenses are the same but what we can now do with them has changed quite a bit.

For example, here is a video of Mars through a small telescope: http://i.imgur.com˸juHPdn.gifv

If we take the best parts of each video frame in that video and combine them in a smart way, a process called lucky imaging, we can reduce the impact of the atmosphere: http://i.imgur.com˼zLZTlv.png

I wonder how much of that work would be generalizable through specialized neural nets: https:/˺rxiv.org⾫s�.00403

Regarding your paper, I have to remind you that Michael got nice results from upsampling the images before running his software. I actually planned on using the texture units for this, to save on bandwidth𯫝ress calculation overhead in the pending partial rewrite of my software. The GAN there also uses just a single frame, whereas this uses the properties of the distribution of the distortions when seen in the frequency domain to figure out how the distortions are most likely, and then combines the SNR from the many frames to a single image. There is research using a method very similar to Michael's with a GPU, GTX 580 or so iirc, which does >15 fps @720p in real time, with less than 2 frames latency and no more than 1 frame necessary latency if you run the GPU work queues rather empty (risking underutilisation if you don't get CPU time fast enough again). Combine with e.g. a nice Volta DGX, and something like a 400mm Schmidt camera including a field flattening lens and a CMOSIS CMV12000 (like, take the sensor out of an AXIOM beta camera, shrink the board around it to the smallest you can get, and stick it with a lens on top facing a 20 cm spherical mirror, with a corrective plate

80cm from the mirror. This is about

1000$optics, 2500$ image hardware (including that necessary to get the full stream at >100 fps into the DGX), and whatever rent you pay for the DGX. Distortion free 10x slow motion with a pixel size of 14mm at 1km distance.

## This is a Photo of Neptune, From the Ground! ESO's New Adaptive Optics Makes Ground Telescopes Ignore the Earth's Atmosphere - Universe Today

Wow, this is huge. Ever since the voyager flyby the cold gas giants haven't had much attention. Hopefully this new technique produces some good science!

Agreed, this is almost as good as a flyby, at much lower cost. I can't wait to see what the upcoming larger telescope designs are capable of.

Not completely ignore because they still cant receive light the atmosphere wont transmit but they certainly claifiy what it can.

This is incredible. Assuming this can be replicated for all observations with ground-based telescopes, the Hubble Space Telescope and its successor may no longer be needed.

I wonder if this can also help in imaging Kuiper Belt Objects.

The HST is already near the end of its life (and way beyond its design life).

The telescope that's usually quoted as the successor to Hubble is the James Webb Space Telescope (JWST). However, the JWST is largely designed to observe in the infrared rather than the visible. Observations taken from the ground at wavelengths larger than about 5 um are almost entirely prohibited by atmospheric absorbance and scattering and the JWST is designed to observe out to nearly 29 um. Unlike the mild absorbance and slight distortions the technology in the article is addressing, basically no light from beyond 5 um makes it to the ground at all (until you go to much, much longer wavelengths, which is why we can do most radio astronomy from the ground), so this technology will not make space telescopes in general obsolete.

Atmospheric distortion correction is not actually new at all, and the JWST was designed with those improved ground-based telescopes in mind. This is just a new improvement on that -- which is no less impressive -- just that it comes as no great surprise to the designers of future missions.

As for observing Kuiper Belt Objects with this new telescope, I imagine it'll certainly help! given how much smaller and farther they are than Neptune, I doubt we'll get good surface images directly, but weɽ still get better data in astrometry and maybe even spectroscopy. We may also be able to map the surface of a KBO with this if we find one with an eclipsing moon, as we were able to do with Hubble and Pluto/Charon.

## Supersharp Images from New VLT Adaptive Optics

ESO’s Very Large Telescope (VLT) has achieved first light with a new adaptive optics mode called laser tomography — and has captured remarkably sharp test images of the planet Neptune, star clusters and other objects. The pioneering MUSE instrument in Narrow-Field Mode, working with the GALACSI adaptive optics module, can now use this new technique to correct for turbulence at different altitudes in the atmosphere. It is now possible to capture images from the ground at visible wavelengths that are sharper than those from the NASA/ESA Hubble Space Telescope. The combination of exquisite image sharpness and the spectroscopic capabilities of MUSE will enable astronomers to study the properties of astronomical objects in much greater detail than was possible before.

The MUSE (Multi Unit Spectroscopic Explorer) instrument on ESO’s Very Large Telescope (VLT) works with an adaptive optics unit called GALACSI. This makes use of the Laser Guide Star Facility, 4LGSF, a subsystem of the Adaptive Optics Facility (AOF). The AOF provides adaptive optics for instruments on the VLTs Unit Telescope 4 (UT4). MUSE was the first instrument to benefit from this new facility and it now has two adaptive optics modes — the Wide Field Mode and the Narrow Field Mode [1].

The MUSE Wide Field Mode coupled to GALACSI in ground-layer mode corrects for the effects of atmospheric turbulence up to one kilometre above the telescope over a comparatively wide field of view. But the new Narrow Field Mode using laser tomography corrects for almost all of the atmospheric turbulence above the telescope to create much sharper images, but over a smaller region of the sky [2].

With this new capability, the 8-metre UT4 reaches the theoretical limit of image sharpness and is no longer limited by atmospheric blur. This is extremely difficult to attain in the visible and gives images comparable in sharpness to those from the NASA/ESA Hubble Space Telescope. It will enable astronomers to study in unprecedented detail fascinating objects such as supermassive black holes at the centres of distant galaxies, jets from young stars, globular clusters, supernovae, planets and their satellites in the Solar System and much more.

Adaptive optics is a technique to compensate for the blurring effect of the Earth’s atmosphere, also known as astronomical seeing, which is a big problem faced by all ground-based telescopes. The same turbulence in the atmosphere that causes stars to twinkle to the naked eye results in blurred images of the Universe for large telescopes. Light from stars and galaxies becomes distorted as it passes through our atmosphere, and astronomers must use clever technology to improve image quality artificially.

To achieve this four brilliant lasers are fixed to UT4 that project columns of intense orange light 30 centimetres in diameter into the sky, stimulating sodium atoms high in the atmosphere and creating artificial Laser Guide Stars. Adaptive optics systems use the light from these “stars” to determine the turbulence in the atmosphere and calculate corrections one thousand times per second, commanding the thin, deformable secondary mirror of UT4 to constantly alter its shape, correcting for the distorted light.

MUSE is not the only instrument to benefit from the Adaptive Optics Facility. Another adaptive optics system, GRAAL, is already in use with the infrared camera HAWK-I. This will be followed in a few years by the powerful new instrument ERIS. Together these major developments in adaptive optics are enhancing the already powerful fleet of ESO telescopes, bringing the Universe into focus.

This new mode also constitutes a major step forward for the ESO’s Extremely Large Telescope , which will need Laser Tomography to reach its science goals. These results on UT4 with the AOF will help to bring ELT’s engineers and scientists closer to implementing similar adaptive optics technology on the 39-metre giant.

### Notes

[1] MUSE and GALACSI in Wide-Field Mode already provides a correction over a 1.0-arcminute-wide field of view, with pixels 0.2 by 0.2 arcseconds in size. This new Narrow-Field Mode from GALACSI covers a much smaller 7.5-arcsecond field of view, but with much smaller pixels just 0.025 by 0.025 arcseconds to fully exploit the exquisite resolution.

[2] Atmospheric turbulence varies with altitude some layers cause more degradation to the light beam from stars than others. The complex adaptive optics technique of Laser Tomography aims to correct mainly the turbulence of these atmospheric layers. A set of pre-defined layers are selected for the MUSE/GALACSI Narrow Field Mode at 0 km (ground layer always an important contributor), 3, 9 and 14 km altitude. The correction algorithm is then optimised for these layers to enable astronomers to reach an image quality almost as good as with a natural guide star and matching the theoretical limit of the telescope.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 15 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

## Adaptive Optics Ushers In A New Era In Ground-Based Astronomy

SANTA CRUZ, CA -- Adaptive optics technology can remove the blurring effect of the Earth's atmosphere that has long plagued astronomers, allowing ground-based telescopes to achieve a clarity of vision previously attainable only by space-based instruments. Current adaptive optics (AO) systems are able to make images that are superior to those of the Hubble Space Telescope in infrared light.

The technology still has limitations, however. For example, today's adaptive optics systems on the largest telescopes are not able to correct visible-light images. Advanced AO systems now in development are expected to greatly expand the applications for adaptive optics, and will be essential for the next generation of extremely large telescopes now in the planning stages.

"Adaptive optics is working well today on several large telescopes, but for the giant telescopes of the future, the adaptive optics systems will have to be significantly more sophisticated than they are now," said Jerry Nelson, director of the Center for Adaptive Optics (CfAO), a National Science Foundation (NSF) Science and Technology Center based at the University of California, Santa Cruz. Established in 1999, the CfAO plays a key role in the advancement of adaptive optics technology through a network of partners that includes academic institutions, national laboratories, and companies in related industries.

Already, astronomers have been thrilled by the results achieved with adaptive optics systems operating at some of the world's major observatories. At the W. M. Keck Observatory in Hawaii, for example, adaptive optics technology has produced eightfold improvements in image quality, said the obervatory's director, Frederic H. Chaffee.

"When the Keck II Telescope was first 'fitted' with adaptive optics in 1999, the effect was as dramatic as someone who has had 20/150 vision all his life getting fitted with glasses and seeing the world with 20/20 eyes for the first time," Chaffee said. "With adaptive optics, the Keck Telescopes are giving astronomers unprecedented views of the planets and their moons, nearby stars, and distant galaxies. It's a whole new universe out there."

Andrea Ghez, an associate director of the CfAO and professor of astronomy and physics at UCLA, is using the AO system on the Keck Telescopes to study the black hole at the center of our home galaxy, the Milky Way. Ghez first demonstrated the existence of a supermassive black hole at the galactic center using a technique called speckle interferometry, a precursor to adaptive optics.

"It was sort of poor-man's adaptive optics, and it provided very limited information compared to what we are now able to gather using adaptive optics," she said. "For example, we can now start to use spectroscopy to understand the types of stars that are located in the vicinity of the black hole, and we are getting some very surprising results."

An adaptive optics system uses a point source of light as a reference beacon to measure the effects of the atmosphere. The light is analyzed by a detector, called a wavefront sensor, that measures how the light waves were distorted as they passed through the atmosphere. The light collected by the telescope is then bounced off a deformable mirror that changes shape to counteract the distortions measured by the wavefront sensor. A high-speed computer calculates the necessary corrections several hundred times per second, enabling the system to respond to the constantly changing turbulence of the atmosphere.

The light source for the reference beacon can be a bright star in the sky--either the same star being studied or a star adjacent to the object of interest, which might be a faint, distant galaxy. Relying on these "natural" guide stars, however, limits AO observations to the small fraction of the sky that is close to relatively bright stars--only about 1 percent of the sky. So researchers have devised ways of creating artificial guide stars using powerful lasers.

Laser guide stars are still being perfected, however, and most AO observations are still done using natural guide stars. Searching for planets and other dim objects around nearby stars is a natural application for this approach, said CfAO director Nelson.

"A bright star gives off a lot of light that gets spread out by the atmosphere, producing a haze that blocks your ability to see faint things nearby, such as a planet, a red dwarf, or a disk of dust where planets may be forming," Nelson said.

Adaptive optics can be used to concentrate the starlight into a smaller region, while at the same time concentrating the light from faint objects, making them easier to detect. This can be done to some extent with current AO systems, as was demonstrated early this year by astronomers at the University of Hawaii and UC Berkeley who used the AO systems on the Gemini North and Keck Telescopes to obtain images of a brown dwarf in a close orbit around its parent star. Researchers are also working to develop specialized "extreme AO" systems that are specifically tailored for such high-contrast observations.

"You need a lot of light to do this, so it will only work around bright stars. But that's where we want to look anyway to find planets," Nelson said. "I think in the next two to three years we can expect dramatic improvements in this area."

Currently, only the 3-meter Shane Telescope at UC's Lick Observatory has an operational laser guide star that astronomers are using for observations. Within the next few months, however, researchers expect to begin using a laser guide star system recently installed on the 10-meter Keck II Telescope. CfAO researchers at UCSC and Lawrence Livermore National Laboratory (LLNL) are working with the observatory's staff to integrate the laser with the Keck AO system and optimize its performance.

"The laser guide star allows us to make observations anywhere in the sky using adaptive optics," said CfAO associate director Claire Max.

Max, a professor of astronomy and astrophysics at UCSC with a joint appointment at LLNL, led the LLNL teams that developed laser guide stars for the Lick and Keck Observatories. The Lick AO system was also built by her group at LLNL, and the Keck AO system was built in a partnership between LLNL and the Keck Observatory.

At both Lick and Keck, a powerful laser tuned to the wavelength at which sodium atoms absorb and emit light is used to create a glowing spot in a sodium-rich layer of the upper atmosphere. This artificial star is not visible to the naked eye, but it provides enough light for the AO system's wavefront sensor to analyze. Building the specialized lasers is expensive, however, and operating them can be challenging.

"They are really prototypes, and we need to develop better laser technology to make it broadly useful to more observatories," Max said.

The cutting edge of adaptive optics technology is an area called multi-conjugate AO, which requires multiple laser beacons in the sky. There are many challenges to be overcome, but Nelson predicted that a multi-conjugate AO system will be in place on the Gemini South Telescope in about 5 years.

"Designing multi-conjugate AO systems is a high priority for the CfAO," Nelson said. "At a qualitative level, we understand how to go about building one of these systems, but it will not be easy. The analytical tools are far from complete, and the technology for the mirrors and the lasers is also very challenging. But it's the only reasonable way to build AO systems for the giant telescopes with 30-meter or 50-meter mirrors that are being planned for the future."

In the meantime, researchers are eager to begin using the Keck laser guide star--especially those studying extremely faint, distant galaxies. Astronomers James Larkin at UCLA and David Koo and Eric Steinbring at UCSC have used the Keck AO system with natural guide stars to study a handful of distant galaxies, some of which had already been imaged by the Hubble Space Telescope (HST). HST and Keck provide complementary information, because the HST works best for imaging visible light, or "optical" wavelengths, whereas adaptive optics works best at near infrared wavelengths.

"With adaptive optics, the Keck Telescopes can outperform the Hubble in the near infrared, which means we can now look at these very distant galaxies not only in the optical range with the Hubble, but also with the same precision and sharpness in the near infrared with Keck," said Koo, a professor of astronomy and astrophysics at UCSC.

This is important because the redshift effect, whereby light from distant objects is shifted to longer wavelengths by the expansion of the universe, causes the visible light originally emitted by these distant galaxies to be shifted into the near infrared by the time it reaches Earth.

"When you look in the near infrared with adaptive optics, you're seeing the original visible light from these galaxies, while the optical images from Hubble are actually the original ultraviolet light," said Steinbring, a postdoctoral researcher working with Koo.

The sharpness, or resolution, of the Keck AO images is just good enough to distinguish important structural features of the galaxies, such as spiral arms and central bulges, Koo said. With the laser guide star, astronomers will get that same resolution all over the sky, which will enable them to study many more distant galaxies, gathering valuable clues about the processes involved in galaxy formation. The small sample studied so far doesn't provide much information about galaxy formation, but it does show that adaptive optics is a very powerful tool for studying faint galaxies, Steinbring said.

"It wasn't obvious at first that this would work, so it's exciting that we can do this at all from ground-based telescopes," he said.

## ESO's Very Large Telescope now provides better images than the Hubble

European Southern Observatory's (ESO) Very Large Telescope (VLT) has a new adaptive optics mode, which now allows them to get better and sharper images than the Hubble!

At the top of this post is their new image of Neptune, compare it with the Hubble's image:

Thing is, VLT is 4 times larger than the Hubble, but due to being located on earth it has to deal with lots of atmospheric turbulence, which makes space images blurry. Adaptive optics systems are a real game changer here, using artificial "laser guide stars" to compensate for those turbulences.

Compare the new image with the one taken without using the adaptive optics:

Wow, what a difference does it make!

To achieve this, the observatory blasts four powerful lasers into the sky, in order to create artificial stars and monitor how they're distorted by atmospheric turbulences:

WoW that’s amazing that they achieved that with a ground based telescope! I can’t wait to see some other objects.

They also published this comparison image of a star cluster:

Middle inset: without adaptive optics, inset on the right: with adaptive optics.

To achieve this, the observatory blasts four powerful lasers into the sky, in order to create artificial stars and monitor how they're distorted by atmospheric turbulences:

Clever guys. It's wonderful what these scientists do and thank God they have the funding to push back the boundaries. The VLT could change our way of looking at the universe like the Hubble did. It was only recently when they published an image of a planet at the beginning of its life. I'm looking forward to the new images and their ingenious fine tuning.

I can't wait for when ESO's Extremely Large Telescope goes into service. It will have a primary mirror of nearly 40 meters in diameter (The Hubble's is only 2 m, and VLT's 8 m). It will already exceed Hubble's resolution, but with this new mode of adaptive optics, the results would be unimaginably better. Since this new mode practically removes any atmospheric influence, it would be like having a 40-meter space telescope!

Thanks for those extra tidbits, I am just stunned! I love this! That video is friggin jaw dropping it really puts it into perspective. Just fascinating S&F

It makes the mouth water, doesn't it? I was just reading around their achievements and wondering if they'll be doing any 'signs of life' searches? Imagine when the James Webb is fully active and something like this ELT in tandem? Will the ELT be used for similar pursuits?

Hubble's an old girl now so no surprise technology is passing her by , nice to see ESO making advancements in ground based technology and getting results that exceed space based options given the failure by NASA to get JWST off the ground.

It makes the mouth water, doesn't it? I was just reading around their achievements and wondering if they'll be doing any 'signs of life' searches? Imagine when the James Webb is fully active and something like this ELT in tandem? Will the ELT be used for similar pursuits?

I saw the ESO have done work (years ago) analysing the composition of space within galaxies. It made me wonder if this new level of accuracy will aid the refraction of exoplanetary atmospheres for signs of life. Not just production of heavy metals associated with technology, but mainly for signals of Cambrian explosions and so forth. Yeah, I know these may well be very, very rare, but more likely than technologies.

Any/every technological world will have passed through some kind of atmospheric process towards being habitable. Based on our sample of one (lol), we can expect the process of oxygenating an atmosphere to occupy a larger period of time than developing technology or smelting metals. Looking for Goldilocks atmospheres could be a lot of fun.

## Author information

### Affiliations

Departamento de Astronomía, Universidad de Chile, Las Condes, Chile

James S. Jenkins, Matías R. Díaz, Nicolás T. Kurtovic, Jose I. Vines, Pablo A. Peña Rojas & Pía Cortés-Zuleta

Centro de Astrofísica y Tecnologías Afines (CATA), Santiago, Chile

James S. Jenkins & Matías R. Díaz

Space Telescope Science Institute, Baltimore, MD, USA

Center of Astro-Engineering UC, Pontificia Universidad Católica de Chile, Santiago, Chile

Rafael Brahm & Pascal Torres

Millennium Institute for Astrophysics, Santiago, Chile

Rafael Brahm & Andrés Jordán

School of Physics and Astronomy, Queen Mary University of London, London, UK

NASA Goddard Space Flight Center, Greenbelt, MD, USA

Department of Physics, University of Warwick, Coventry, UK

George W. King, Peter J. Wheatley, David J. Armstrong, Daniel Bayliss, Edward M. Bryant, Benjamin F. Cooke, Emma Foxell, Boris T. Gänsicke, Samuel Gill, James A. G. Jackman, Tom Louden, James McCormac, Don Pollacco, Simon. R. Walker & Richard G. West

Centre for Exoplanets and Habitability, University of Warwick, Coventry, UK

George W. King, Peter J. Wheatley, David J. Armstrong, Edward M. Bryant, Benjamin F. Cooke, Emma Foxell, Samuel Gill, James A. G. Jackman, Tom Louden, James McCormac, Don Pollacco & Richard G. West

Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA

NASA Exoplanet Science Institute, Caltech, Pasadena, CA, USA

David R. Ciardi, Charles A. Beichman & Jessie L. Christiansen

Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA, USA

George Ricker, Sara Seager, Christopher J. Burke, Jesus Noel Villaseñor, Michael Vezie & Maximilian N. Günther

Royal Observatory of Belgium, Brussels, Belgium

Center for Astrophysics | Harvard and Smithsonian, Cambridge, MA, USA

David W. Latham, Allyson Bieryla, Samuel N. Quinn & Karen A. Collins

Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

NASA Ames Research Center, Moffett Field, CA, USA

Jon M. Jenkins, Christopher E. Henze, Todd C. Klaus, Sean McCauliff & Jack J. Lissauer

Department of Astronomy, The University of Tokyo, Tokyo, Japan

Mayuko Mori, Motohide Tamura & Jerome Pitogo de Leon

Komaba Institute for Science, The University of Tokyo, Tokyo, Japan

Astrobiology Center, Tokyo, Japan

Norio Narita & Motohide Tamura

National Astronomical Observatory of Japan, Tokyo, Japan

Norio Narita & Motohide Tamura

Instituto de Astrofísica de Canarias (IAC), Tenerife, Spain

Norio Narita & Enric Palle

Department of Physics, Kyoto Sangyo University, Kyoto, Japan

George Mason University, Fairfax, VA, USA

Campo Catino Astronomical Observatory, Guarcino, Italy

Giovanni Isopi, Franco Mallia & Andrea Ercolino

Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, Ontario, Canada

Department of Physics and Astronomy, University of Leicester, Leicester, UK

Jack S. Acton, Claudia Belardi, Matthew R. Burleigh, Sarah L. Casewell, Michael R. Goad, Liam Raynard & Rosanna H. Tilbrook

Observatoire de Genéve, Université de Genéve, Sauverny, Switzerland

François Bouchy, Louise D. Nielsen, Oliver Turner & Stéphane Udry

Institute of Planetary Research, German Aerospace Center, Berlin, Germany

Juan Cabrera, Philipp Eigmüller, Anders Erikson, Heike Rauer, Alexis M. S. Smith & Ruth Titz-Weider

Center for Astronomy and Astrophysics, TU Berlin, Berlin, Germany

Alexander Chaushev & Heike Rauer

Astrophysics Group, Cavendish Laboratory, Cambridge, UK

Edward Gillen & Didier Queloz

Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, UK

Matthew J. Hooton & Christopher A. Watson

Instituto de Astronomía, Universidad Católica del Norte, Antofagasta, Chile

Institute of Geological Sciences, FU Berlin, Berlin, Germany

Departamento de Astrofísica, Universidad de La Laguna (ULL), Tenerife, Spain

Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, Canada

Department of Physics and Astronomy, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

Nicholas Law & Andrew W. Mann

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### Contributions

J.S.J. led the TESS precision radial-velocity follow-up programme, selection of the targets, analysis and project coordination, and wrote the bulk of the paper. M.D., N.T. and R.B. performed the HARPS radial-velocity observations, P.T. observed the star with Coralie and M.D. analysed the activity data from these sources. N.E. performed the global modelling, with P.C.-Z. performing the TTV analysis, and R.B., M.G.S. and A.B. performing the stellar characterization using the spectra and evolutionary models. P.A.P.R. worked on the EMPEROR code and assisted in fitting the HARPS radial velocities. E.D.L. created a structure model for the planet, and in addition to G.W.K. and P.J.W., performed photoevaporation modelling. J.N.W. performed analysis of the system parameters. D.R.C. led the Keck NIRC2 observations and analysis. G.R., R.V., D.W.L., S.S. and J.M.J. have been leading the TESS project, observations, organization of the mission, processing of the data, organization of the working groups, selection of the targets and dissemination of the data products. C.E.H., S.M. and T.K. worked on the SPOC data pipeline. C.J.B. was a member of the TOI discovery team. S.N.Q. contributed to TOI vetting, TFOP organization and TRES spectral analysis. J.L. and C.P. helped with the interpretation of the system formation and evolution. K.A.C. contributed to TOI vetting, TFOP organization, and TFOP SG1 ground-based time-series photometry analysis. G.I., F.M., A.E., K.I.C., M.M., N.N., T.N. and J.P.L. contributed TFOP SG1 observations. J.S.A., D.J.A., D.B., F.B., C.B., E.M.B., M.R.B., J.C., S.L.C., A.C., B.F.C., P.E., A.E., E.F., B.T.G., S.G., E.G., M.N.G., M.R.G., M.J.H., J.A.G.J., T.L., J.M., M.M., L.D.N., D.P., D.Q., H.R., L.R., A.M.S.S., R.H.T., R.T.-W., O.T., S.U., J.I.V., S.R.W., C.A.W., R.G.W., P.J.W. and G.W.K. are part of the NGTS consortium who provided follow-up observations to confirm the planet. E.P. and J.J.L. helped with the interpretation of the result. C.B. performed the observations at SOAR and reduced the data, C.Z. performed the data analysis, and N.L. and A.W.M. assisted in the survey proposal, analysis and telescope time acquisition. All authors contributed to the paper.

## Astronomy Final Exam

The Orion Nebula is about 1600 light years away from Earth. You need to know that but it may not be in the book, so it is provided in this problem.

the mass of the cloud increases as it collapses

total gravitational force is a conserved quantity

Stays constant at all times

kinetic energy being converted to radiative energy

thermal energy being converted to radiative energy

A. the quantum state of one particle instantaneously determines the quantum state of its entangled particle even if it is far away.

B. the quantum states of entangled particles exists even before any measurement is made.

A. The planet must be geologically active, that is, have volcanoes, planetquakes, and erosion from weather.

B. The planet must have an atmosphere.

C. The planet must have a molten interior.

D. The planet must have a rocky surface.

A. the distance from the Sun where temperatures were low enough for hydrogen and helium to condense, between the present-day orbits of Jupiter and Saturn

B. the distance from the Sun where temperatures were low enough for metals to condense, between the Sun and the present-day orbit of Mercury

C. the distance from the Sun where temperatures were low enough for rocks to condense, between the present-day orbits of Mercury and Venus

D. the distance from the Sun where temperatures were low enough for asteroids to form, between the present-day orbits of Venus and Earth

## The Resolution of a Telescope

In addition to gathering as much light as they can, astronomers also want to have the sharpest images possible. Resolution refers to the precision of detail present in an image: that is, the smallest features that can be distinguished. Astronomers are always eager to make out more detail in the images they study, whether they are following the weather on Jupiter or trying to peer into the violent heart of a &ldquocannibal galaxy&rdquo that recently ate its neighbor for lunch.

One factor that determines how good the resolution will be is the size of the telescope. Larger apertures produce sharper images. Until very recently, however, visible-light and infrared telescopes on Earth&rsquos surface could not produce images as sharp as the theory of light said they should.

The problem&mdashas we saw earlier in this chapter&mdashis our planet&rsquos atmosphere, which is turbulent. It contains many small-scale blobs or cells of gas that range in size from inches to several feet. Each cell has a slightly different temperature from its neighbor, and each cell acts like a lens, bending (refracting) the path of the light by a small amount. This bending slightly changes the position where each light ray finally reaches the detector in a telescope. The cells of air are in motion, constantly being blown through the light path of the telescope by winds, often in different directions at different altitudes. As a result, the path followed by the light is constantly changing.

For an analogy, think about watching a parade from a window high up in a skyscraper. You decide to throw some confetti down toward the marchers. Even if you drop a handful all at the same time and in the same direction, air currents will toss the pieces around, and they will reach the ground at different places. As we described earlier, we can think of the light from the stars as a series of parallel beams, each making its way through the atmosphere. Each path will be slightly different, and each will reach the detector of the telescope at a slightly different place. The result is a blurred image, and because the cells are being blown by the wind, the nature of the blur will change many times each second. You have probably noticed this effect as the &ldquotwinkling&rdquo of stars seen from Earth. The light beams are bent enough that part of the time they reach your eye, and part of the time some of them miss, thereby making the star seem to vary in brightness. In space, however, the light of the stars is steady.

Astronomers search the world for locations where the amount of atmospheric blurring, or turbulence, is as small as possible. It turns out that the best sites are in coastal mountain ranges and on isolated volcanic peaks in the middle of an ocean. Air that has flowed long distances over water before it encounters land is especially stable.

The resolution of an image is measured in units of angle on the sky, typically in units of arcseconds. One arcsecond is 1/3600 degree, and there are 360 degrees in a full circle. So we are talking about tiny angles on the sky. To give you a sense of just how tiny, we might note that 1 arcsecond is how big a quarter would look when seen from a distance of 5 kilometers. The best images obtained from the ground with traditional techniques reveal details as small as several tenths of an arcsecond across. This image size is remarkably good. One of the main reasons for launching the Hubble Space Telescope was to escape Earth&rsquos atmosphere and obtain even sharper images.

But since we can&rsquot put every telescope into space, astronomers have devised a technique called adaptive optics that can beat Earth&rsquos atmosphere at its own game of blurring. This technique (which is most effective in the infrared region of the spectrum with our current technology) makes use of a small flexible mirror placed in the beam of a telescope. A sensor measures how much the atmosphere has distorted the image, and as often as 500 times per second, it sends instructions to the flexible mirror on how to change shape in order to compensate for distortions produced by the atmosphere. The light is thus brought back to an almost perfectly sharp focus at the detector. Figure (PageIndex<7>) shows just how effective this technique is. With adaptive optics, ground-based telescopes can achieve resolutions of 0.1 arcsecond or a little better in the infrared region of the spectrum. This impressive figure is the equivalent of the resolution that the Hubble Space Telescope achieves in the visible-light region of the spectrum.

Figure (PageIndex<7>) Power of Adaptive Optics. One of the clearest pictures of Jupiter ever taken from the ground, this image was produced with adaptive optics using an 8-meter-diameter telescope at the Very Large Telescope in Chile. Adaptive optics uses infrared wavelengths to remove atmospheric blurring, resulting in a much clearer image. (credit: modification of work by ESO, F.Marchis, M.Wong (UC Berkeley) E.Marchetti, P.Amico, S.Tordo (ESO))

how astronomers really use telescopes

In the popular view (and some bad movies), an astronomer spends most nights in a cold observatory peering through a telescope, but this is not very accurate today. Most astronomers do not live at observatories, but near the universities or laboratories where they work. An astronomer might spend only a week or so each year observing at the telescope and the rest of the time measuring or analyzing the data acquired from large project collaborations and dedicated surveys. Many astronomers use radio telescopes for space experiments, which work just as well during the daylight hours. Still others work at purely theoretical problems using supercomputers and never observe at a telescope of any kind.

Even when astronomers are observing with large telescopes, they seldom peer through them. Electronic detectors permanently record the data for detailed analysis later. At some observatories, observations may be made remotely, with the astronomer sitting at a computer thousands of miles away from the telescope.

Time on major telescopes is at a premium, and an observatory director will typically receive many more requests for telescope time than can be accommodated during the year. Astronomers must therefore write a convincing proposal explaining how they would like to use the telescope and why their observations will be important to the progress of astronomy. A committee of astronomers is then asked to judge and rank the proposals, and time is assigned only to those with the greatest merit. Even if your proposal is among the high-rated ones, you may have to wait many months for your turn. If the skies are cloudy on the nights you have been assigned, it may be more than a year before you get another chance.

Some older astronomers still remember long, cold nights spent alone in an observatory dome, with only music from a tape recorder or an all-night radio station for company. The sight of the stars shining brilliantly hour after hour through the open slit in the observatory dome was unforgettable. So, too, was the relief as the first pale light of dawn announced the end of a 12-hour observation session. Astronomy is much easier today, with teams of observers working together, often at their computers, in a warm room. Those who are more nostalgic, however, might argue that some of the romance has gone from the field, too.

### Summary

New technologies for creating and supporting lightweight mirrors have led to the construction of a number of large telescopes since 1990. The site for an astronomical observatory must be carefully chosen for clear weather, dark skies, low water vapor, and excellent atmospheric seeing (low atmospheric turbulence). The resolution of a visible-light or infrared telescope is degraded by turbulence in Earth&rsquos atmosphere. The technique of adaptive optics, however, can make corrections for this turbulence in real time and produce exquisitely detailed images.