Articles by "Astronomy"
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at 2:50 AM 0
Webb contains novel technologies that have never previously been flown in space
The US space agency boasts that it will literally "look back in time to see the very first galaxies that formed in the early Universe".

As if those claims were not bold enough, scientists have now surmised that the eventual successor to the world famous and beloved Hubble Space Telescope may - thanks to its 6.5m golden mirror and exquisitely sensitive cameras - have a another extraordinary talent.

The JWST, as it is called, may be able to look for signs of alien life - detecting whether atmospheres of planets orbiting nearby stars are being modified by that life.

Despite this, the project to build it narrowly survived cancellation by the US Government in 2011. That was in no small part down to its (perhaps appropriately) astronomical cost - an estimated $10bn rather than its originally planned $1bn.

Back on Earth, however, astronomers - including the University of Washington team who proposed "life-detection" observations using the telescope - are unerringly thrilled at the prospect of its launch.


How do you detect life on distant planets?
University of Washington astronomer Joshua Krissansen-Totton and his team have looked into whether the telescope could detect signs of what they call "biosignatures" in the atmospheres of planets that are orbiting a nearby star.

"We could do these life-detection observations in the next few years," says Mr Krissansen-Totton.

The basis for this search may lie in JWST being so sensitive to light that it could pick up so-called "atmospheric chemical disequilibrium".

Earth's atmosphere would change if all life was suddenly removed
It may not be a catchy term, but it is an idea with a long heritage, promoted by celebrated scientists James Lovelock and Carl Sagan.

The reasoning is that if all life on Earth disappeared tomorrow, the many gases which make up our atmosphere would undergo natural chemical reactions, and the atmosphere would slowly revert to a different chemical mixture.

It is continually held away from this state by organisms on our planet expelling waste gases as they live.

Because of this, searching for signs of oxygen (or its chemical cousin ozone) has long been thought to be a good way of finding life. But this does rest on the assumption that extraterrestrial life runs by the same biological rules as our own.

It might not. Therefore, assessing atmospheric chemical disequilibrium - looking for other gases and figuring out how far out of kilter from "normal' a planet's atmosphere sits - could be key to finding alien life of any kind.

The chemical make-up of the atmosphere of a planet orbiting another star can be measured in light by carefully measuring the minuscule dip in starlight as the planet passes between us and the star during the planet's orbit. The gases in the planet's atmosphere cause the light reduction to vary with the wavelength - or colour - of light, revealing information about how much of each chemical is present.

Where is the best place to look?
Mr Krissansen-Totton simulated the data that would be obtained if JWST were to look at planets orbiting a small Jupiter-sized star called TRAPPIST-1, about 39.6 light-years away from our Sun. This star caused a sensation in 2017 when it was discovered to host seven Earth-sized planets, several of which could possess liquid water, and hence might be a good bet for hosting life.

The Washington researcher predicts that James Webb could measure the amounts of methane and carbon dioxide in the atmosphere of the fourth planet, TRAPPIST-1e, from the dips in light at wavelengths affected by these gases.

It would be a tough measurement of an unimaginably tiny signal, but Cornell University astronomer Prof Jonathan Lunine, who was not involved in this study, is excited by the prediction, saying "they make the case that this can really be done with JWST".


All seven planets are thought to have Earth-like characteristics

Once the measurement is made, though, Mr Krissansen-Totton explains, "you can then ask the question: do we know of any non-biological processes" that could produce that effect?"

Planetary atmospheres, including our own, he points out, can also be modified by non-biological processes, such as volcanic activity. So, if the atmosphere of TRAPPIST-1e was found to be awry, researchers would then need to rule out any non-biological effects before declaring the existence of extraterrestrial life.

Mr Krissansen-Totton says that "that kind of confirmation is going to require multiple observations, to really make a totally solid case".

"But if we detect something that we don't have an alternative explanation for, I think that would be an incredibly exciting discovery."

Who else will be doing this?
For now, the telescope's golden mirror remains securely locked in a lab in California, and astronomers must continue to wait for these possibilities to be explored.

JWST will be joining a host of new facilities that will subject planets around other stars to some serious scrutiny over the next few decades.

Huge ground-based telescopes in Hawaii and Chile are also planned, and the European Space Agency's UK-led Ariel mission, designed to probe the atmospheres of planets around other stars, will blast off in the late 2020s.

Prof Lunine says: "I think that we're in a remarkable time for understanding our Universe and exploring the cosmos, and James Webb is going to take the next step in that.

"It is going to be truly worth it."

Prof Gillian Wright, principal scientist on the telescope's UK-led Mid-InfraRed instrument, agrees. "We've never had access to something this big in space before," she says.

"To say a telescope will open up new windows on the Universe sounds kind-of cliched, but with James Webb it's really true."

JWST is led by Nasa but is a joint venture with the European and Canadian space agencies. Dr Jonathan Nichols is a planetary scientist from the University of Leicester and a 2018 British Science Association media fellow
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at 7:57 PM 0

Astronomers have spotted more than 100 new potential alien planets, including one in the fourth-closest star system to the sun, a new study reports.

This haul of newfound possible exoplanets, which have yet to be confirmed as bona fide alien worlds, comes from a new analysis of 20 years' worth of data gathered by the HIRES (High Resolution Echelle Spectrometer) instrument at the Keck Observatory in Hawaii.

"HIRES was not specifically optimized to do this type of exoplanet detective work, but has turned out to be a workhorse instrument of the field," study co-author Steve Vogt, of the University of California, Santa Cruz, said in a statement. "I am very happy to contribute to science that is fundamentally changing how we view ourselves in the universe," added Vogt, who designed and built HIRES. [Gallery: The Strangest Alien Planets]

HIRES detects exoplanets using the "radial velocity" method: The instrument picks up the tiny gravitational wobbles that orbiting worlds induce in their parent stars. This strategy is different from that employed by the most prolific planet hunter of all time, NASA's Kepler space telescope; Kepler watches for the tiny brightness dips caused when a planet crosses its star's face — called the "transit method."

In the new study, the researchers identified 60 so-called planet candidates, as well as 54 other suggestive signals that require further investigation before they can be elevated to candidate status.

One of the official candidates circles the star GJ 411 (also known as Lalande 21185), which lies just 8.3 light-years from the sun. Only three star systems are closer. (The three-star Alpha Centauri is the nearest system to the sun. Last August, astronomers announced the discovery of a potentially Earth-like world orbiting Proxima Centauri, one of the Alpha Centauri trio. Proxima Centauri lies 4.22 light-years from Earth.)

The possible GJ 411 planet is at least 3.8 times more massive than Earth, and it's probably too hot to be habitable, study team members said. The candidate world lies quite close to the star, completing one orbit every 10 Earth days.

The huge HIRES data set consists of nearly 61,000 measurements of more than 1,600 stars. To wring the most science possible out of this catalog — which study team members called the biggest compilation of radial-velocity planet-hunting observations ever — the HIRES researchers have shared it with other exoplanet researchers around the world.

The best way to advance the field and further our understanding of what these planets are made out of is to harness the abilities of a variety of precision radial velocity instruments, and deploy them in concert," study team member Jennifer Burt, of the Massachusetts Institute of Technology, said in the same statement. "But that will require some big teams to break from tradition and start leading serious cooperative efforts."

The new study, which was led by Paul Butler of the Carnegie Institution for Science in Washington, D.C., was published in The Astronomical Journal.

To date, astronomers have discovered 3,450 confirmed exoplanets, about two-thirds of which were found by Kepler. Several thousand more await confirmation.

And the finds should keep rolling in well into the future. For example, the European Space Agency's Gaia mission, which launched in December 2013, is expected to discover thousands of alien worlds before its work is done, as is NASA's Transiting Exoplanet Survey Satellite (TESS), which is scheduled to lift off in early 2018. 
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at 2:57 PM 0
Jupiter's iconic storm, the Great Red Spot, may have just clued scientists in on an enthralling secret: the giant planet might have water.
Jupiter is a special world. It's the largest planet in our solar system, and likely was the first body to funnel the sun's leftover elements to form, according to NASA. So, it’s no surprise, then, that researchers once thought Jupiter had an identical composition to the sun.

But subsequent studies of the planet over the last few decades have revealed a Jupiter that is more complex. The hints of water in Jupiter's Great Red Spot come from a recent study by Gordon Bjoraker, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.


"The moons that orbit Jupiter are mostly water ice, so the whole neighborhood has plenty of water," Bjoraker said in a NASA statement Thursday (Aug. 29). "Why wouldn't the planet — which is this huge gravity well, where everything falls into it — be water rich, too?"

Bjoraker and colleagues collected radiation data on Jupiter using two special telescopes on the Mauna Kea summit in Hawaii — an instrument at NASA Infrared Telescope Facility, and the "most sensitive infrared telescope on Earth" at the Keck Observatory, according to the space agency.

To supplement those observations, the team used data from NASA's Juno spacecraft, which can probe deeper into Jupiter's clouds than any mission before. Juno orbits Jupiter once every 53 days.


This enhanced-color image of Jupiter's Great Red Spot was created by citizen scientist Gerald Eichstädt using data from the JunoCam imager on NASA's Juno spacecraft. The image is adjusted and strongly enhanced to draw viewers' eyes to the iconic storm and the turbulence around it.

With ground-based instruments on Earth, the team watched thermal radiation leak from the depths of the Great Red Spot. They found that above the clouds in this turbulent region's abyss, chemical signatures of water existed. Models, both theoretical and computer-generated, support their findings of "abundant" water on Jupiter.

The researchers found that the deepest cloud layer with water signatures inside the Great Red Spot is at 5 bars, or five times the atmospheric pressure on Earth, where the temperatures reach water's freezing point.

This depth, in addition to the levels of carbon monoxide researchers detected on Jupiter, appears to confirm that Jupiter is rich in oxygen, and, since its abundance of hydrogenis already well-known, it has the ingredients for water.
The Great Red Spot is the dark patch in the middle of this infrared image of Jupiter. It is dark due to the thick clouds that block thermal radiation. The yellow strip denotes the portion of the Great Red Spot used in astrophysicist Gordon L. Bjoraker’s analysis.

But how much water could there be on Jupiter? More observations are needed to find out, researchers said.

"Jupiter's water abundance will tell us a lot about how the giant planet formed, but only if we can figure out how much water there is in the entire planet," Steven Levin, a Juno project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said in the statement.

If future observations by Juno confirm the existence of water on Jupiter, and map it in detail, it could potentially be used to help determine if there's water on other gas giant planets.

"If it works, then maybe we can apply it elsewhere, like Saturn, Uranus or Neptune, where we don’t have a Juno," said Amy Simon, a planetary atmospheres expert at NASA Goddard, in the statement.

The paper detailing the findings was published Aug. 17 in The Astronomical Journal.
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