The four 8.2-metre Unit Telescopes of the Very Large Telescope at the Paranal Observatory complex. ESO/VLT
One proposal offers a unique method to directly image ExoEarths, or rocky worlds around nearby stars.
It’s the holy grail of modern exoplanet astronomy. As of writing this, the count of known worlds beyond the solar system stands at 6,520. Most of these are ‘hot Jupiters,’ large worlds in tight orbits around their host star. But what we’d really like to get a look at are ‘ExoEarths,’ rocky worlds (hopefully) like our own.
Distant sprites (right) captured from ESO's VLT by Photo Ambassador Petr Horálek. (P. Horálek/ESO)
At the ESO’s observatories located high in the Atacama Desert of Chile, amazing images of distant objects in the Universe are captured on a regular basis. But in January 2015, ESO photo ambassador Petr Horálek captured some amazing photos of much closer phenomena: red sprites flashing in the atmosphere high above distant thunderstorms.
The photo above was captured from ESO’s Paranal Observatory. A few days earlier during the early morning hours of Jan. 20 Petr captured another series of sprites from the La Silla site, generated by a storm over Argentina over 310 miles (500 km) away.
Sprites spotted from ESO’s La Silla observatory by Petr Horálek (left horizon)
So-named because of their elusive nature, sprites appear as clusters of red tendrils above a lighting flash, often extending as high as 55 miles (90 km) into the atmosphere. The brightest region of a sprite is typically seen at altitudes of over 40-45 miles (65-75 km).
Because they occur high above large storms, only last for fractions of a second and emit light in the portion of the spectrum to which our eyes are the least sensitive, observing sprites is notoriously difficult.
These furtive atmospheric features weren’t captured on camera until 1989. Continuing research has since resulted in more images, including some from the International Space Station. When they are spotted, sprites – and their lower-altitude relatives blue jets – can appear as bright as moderate aurorae and have also been found to emit radio noise. It has even been suggested that looking for sprite activity on other planets could help identify alien environments that are conducive to life.
Find out more about sprite research from the University of Alaska Fairbanks, and check out the PBS NOVA program “At the Edge of Space” below about a sprite hunt in the skies over Denver, CO conducted by a team of American scientists and Japanese filmmakers.
This beautiful photo, taken by ESO photo ambassador Babak Tafreshi, shows the European Southern Observatory’s Very Large Telescope array and VISTA telescope atop the peaks of the Cerro Paranal in Chile’s Atacama Desert. In the distance the Earth’s shadow extends outward toward the horizon, divided from the bluer daytime sky by the dusky pink “Belt of Venus.”
At an altitude of 2,635 meters (8,645 feet) the Paranal looks down onto a sea of clouds covering the Pacific Ocean, visible at right, whose shores lie 12 km in the distance.
Artist’s impression of the surface of Makemake, a dwarf planet beyond Pluto (ESO/L. Calçada/Nick Risinger)
It turns out there’s no air up there: the distant dwarf planet Makemake is surprisingly lacking in an atmosphere, according to findings made by astronomers using telescopes at ESO’s La Silla and Paranal observatories.
An international team of astronomers used the mountaintop telescopes to observe Makemake as it passed in front of a faint background star in April 2011, a brief stellar occultation that lasted only about a minute. By watching how the starlight was blotted out by Makemake, measurements could be made of the dwarf planet’s size, mass and atmosphere — or, in this case, its lack thereof… a finding which surprised some scientists.
“As Makemake passed in front of the star and blocked it out, the star disappeared and reappeared very abruptly, rather than fading and brightening gradually. This means that the little dwarf planet has no significant atmosphere,” said team leader José Luis Ortiz of the Instituto de Astrofísica de Andalucía in Spain. “It was thought that Makemake had a good chance of having developed an atmosphere — that it has no sign of one at all shows just how much we have yet to learn about these mysterious bodies.”
First discovered in 2005, Makemake is an icy dwarf planet about 2/3 the diameter of Pluto — and 19 AU further from the Sun (but not nearly as far as the larger Eris, which is over 96 AU away.) It was thought that Makemake might have a tenuous, seasonal atmosphere similar to what has been found on Pluto, but it now appears that it does not… at least not in any large-scale, global form.
Due to its small size, sheer distance and apparent lack of moons, making scientific observations of Makemake has been a challenge for astronomers. The April 2011 occultation allowed measurements to be made — even if only for a minute — that weren’t possible before, including first-ever calculations of the dwarf planet’s density and albedo.
As it turns out, Makemake’s albedo is about 0.77 — comparable to that of dirty snow… a reflectivity higher than Pluto’s but lower than that of Eris. Its density is estimated to be 1.7 ± 0.3 g/cm³, indicating a composition of mostly ice with some rock.
“Our new observations have greatly improved our knowledge of one of the biggest [icy bodies], Makemake — we will be able to use this information as we explore the intriguing objects in this region of space further,” said Ortiz.
The team’s research was presented in a paper “Albedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation” to appear in the November 22, 2012 issue of the journal Nature.
Inset image: Makemake imaged by Hubble in 2006. (NASA/JPL-Caltech)
An international team of astronomers has figured out a way to determine details of an exoplanet’s atmosphere from 50 light-years away… even though the planet doesn’t transit the face of its star as seen from Earth.
Tau Boötis b is a “hot Jupiter” type of exoplanet, 6 times more massive than Jupiter. It was the first planet to be identified orbiting its parent star, Tau Boötis, located 50 light-years away. It’s also one of the first exoplanets we’ve known about, discovered in 1996 via the radial velocity method — that is, Tau Boötis b exerts a slight tug on its star, shifting its position enough to be detectable from Earth. But the exoplanet doesn’t pass in front of its star like some others do, which until now made measurements of its atmosphere impossible.
Today, an international team of scientists working with the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile have announced the success of a “clever new trick” of examining such non-transiting exoplanet atmospheres. By gathering high-quality infrared observations of the Tau Boötis system with the VLT’s CRIRES instrument the researchers were able to differentiate the radiation coming from the planet versus that emitted by its star, allowing the velocity and mass of Tau Boötis b to be determined.
“Thanks to the high quality observations provided by the VLT and CRIRES we were able to study the spectrum of the system in much more detail than has been possible before,” said Ignas Snellen with Leiden Observatory in the Netherlands, co-author of the research paper. “Only about 0.01% of the light we see comes from the planet, and the rest from the star, so this was not easy.”
Using this technique, the researchers determined that Tau Boötis b’s thick atmosphere contains carbon monoxide and, curiously, exhibits cooler temperatures at higher altitudes — the opposite of what’s been found on other hot Jupiter exoplanets.
“Maybe one day we may even find evidence for biological activity on Earth-like planets in this way.”
– Ignas Snellen, Leiden Observatory, the Netherlands
In addition to atmospheric details, the team was also able to use the new method to determine Tau Boötis b’s mass and orbital angle — 44 degrees, another detail not previously identifiable.
“The new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before,” said Snellen. “This is a big step forward.
“Maybe one day we may even find evidence for biological activity on Earth-like planets in this way.”
This research was presented in a paper “The signature of orbital motion from the dayside of the planet Tau Boötis b”, to appear in the journal Nature on June 28, 2012.
Added 6/27: The team’s paper can be found on arXiv here.
Top image: artist’s impression of the exoplanet Tau Boötis b. (ESO/L. Calçada). Side image: ESO’s VLT telescopes at the Paranal Observatory in Chile’s Atacama desert. (Iztok Boncina/ESO)
The VLT's laser beam creates a "false star" for adaptive optics calibration. (ESO/Y. Beletsky)
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Located high in the mountains of Chile’s Atacama Desert, the enormous telescopes of the European Southern Observatory have been providing astronomers with unprecedented views of the night sky for 50 years. ESO’s suite of telescopes take advantage of the cold, clear air over the Atacama, which is one of the driest places on Earth. But as clear as it is, there is still some turbulence and variations to contend with — especially when peering billions of light-years out into the Universe.
So how do they do it?
Thanks to adaptive optics and advanced laser calibration, ESO can negate the effects of atmospheric turbulence, bringing the distant Universe into focus. It’s an impressive orchestration of innovation and engineering and the ESO team has put together a video to show us how it’s done.
We all love the images (and the science) so here’s a look behind the scenes!
Mosaic of infrared survey images from ESO's VISTA reveal over 200,000 distant galaxies. (ESO/UltraVISTA team. Acknowledgement: TERAPIX/CNRS/INSU/CASU.)
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See all those tiny points of light in this image? Most of them aren’t stars; they’re entire galaxies, seen by the European Southern Observatory’s VISTA survey telescope located at the Paranal Observatory in Chile.
This is a combination of over 6000 images taken with a total exposure time of 55 hours, and is the widest deep view of the sky ever taken in infrared light.
The galaxies in this VISTA image are only visible in infrared light because they are very far away. The ever-increasing expansion rate of the Universe shifts the light coming from the most distant objects (like early galaxies) out of visible wavelengths and into the infrared spectrum.
ESO’s VISTA (Visual and Infrared Survey Telescope for Astronomy) telescope is the world’s largest and most powerful infrared observatory, and has the ability to peer deep into the Universe to reveal these incredibly distant, incredibly ancient structures.
By studying such faraway objects astronomers can better understand how the structures of galaxies and galactic clusters evolved throughout time.
The region seen in this deep view is an otherwise “unremarkable” and apparently empty section of sky located in the constellation Sextans.
Erasure's Andy Bell in front of ESO's Very Large Telescope array. Credit: S. Lowery/Erasure/ESO.
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British synthpop band Erasure released a video today featuring lead singer Andy Bell in front of the telescopes of ESO’s Paranal Observatory, located high in the mountains of Chile’s Atacama Desert. The new single “Fill Us With Fire” honors ESO’s 50th anniversary this year. Watch the full video below!
The video features the Very Large Telescope as well as some of ESO’s stunning images of the night sky. This is the third single to be released from their 2011 album Tomorrow’s World.
Andy spent one day at Paranal in February 2012, during which time footage was shot of him singing Erasure’s latest single. The footage was edited with some of ESO’s best astronomical images. Andy, thrilled with the result, decided to dedicate it to ESO’s 50th Anniversary and make it the exclusive video for the single.
Shooting the Fill Us With Fire video. (F. Huber/Erasure/ESO)
Standing on a 20-foot-high platform in front of the VLT, Andy didn’t have a lot of room to move around during the shooting of the video. Say what you will about the choreography, I think it’s awesome to see the observatory and some of its amazing images featured in a new music video!
Personally, I would have wanted to be standing on top of one of the telescope domes but I’m not sure if that’s allowed.
Credit: Erasure/ESO (S. Lowery)
Directed by: Simon Lowery
Editing: Simon Lowery, Lars Lindberg Christensen & Patrick Geeraert
Music: Erasure/Andy Bell
Footage and photos: ESO, Guillaume Blanchard & Simon Lowery
The first released VST image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula. Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute.
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There’s a new telescope at the Paranal Observatory in Chile and what big eyes it has! The VLT Survey Telescope (VST) is a wide-field survey telescope with a field of view twice as broad as the full Moon, enabling new, spectacular views of the cosmos. It is the largest telescope in the world designed to exclusively survey the sky in visible light. Over the next few years the VST and its camera OmegaCAM will make several very detailed surveys of the southern sky.
The first image released from these new eyes on the Universe is a spectacular view star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, shown above. The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across the entire image.
This new image may be the best portrait of the globular star cluster Omega Centauri ever made. Omega Centauri, in the constellation of Centaurus (The Centaur), is the largest globular cluster in the sky, but the very wide field of view of VST and its powerful camera OmegaCAM can encompass even the faint outer regions of this spectacular object. Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: A. Grado/INAF-Capodimonte Observatory
The second image is the globular star cluster Omega Centauri. This is the largest globular cluster in the sky, but the very wide field of view of VST and OmegaCAM allows even the faint outer regions to be seen clearly. This view includes about 300,000 stars.
Here’s a look at the new telescope:
The VLT Survey Telescope (VST) is the latest telescope to be added to ESO’s Paranal Observatory in the Atacama Desert of northern Chile. Credit: ESO/G. Lombardi
Below is a timelapse sequences of the VST enclosure at night:
