Miscellaneous Topics

[Husky]

Can hopefully expect more of these in the future:



edition.cnn.com/2014/04/17/tech/space-earth-size-planet/

NASA discovers Earth-sized planet that may sustain life



By Josh Levs, CNN

April 18, 2014 -- Updated 0558 GMT (1358 HKT) |



An artist's rendering of Kepler-186f, the first discovered Earth-sized planet that may be habitable

STORY HIGHLIGHTS



* Researchers find an Earth-sized planet that may be habitable

* It "proves the existence of worlds that might be similar to our own," institute says

* Scientists are looking for emissions that could suggest extraterrestrial life

* Previously discovered worlds were larger than Earth



(CNN) -- It's like finding a needle in a universe-wide haystack. Researchers have located a planet roughly the size of Earth that could be habitable.



Designated Kepler-186f, the planet is 490 light-years away. But in the search for worlds similar to ours, nothing has come closer.



"This is the first definitive Earth-sized planet found in the habitable zone around another star," said Elisa Quintana of the Search for Extraterrestrial Intelligence (SETI) Institute at NASA. "Finding such planets is a primary goal of the Kepler space telescope."

Photos: Where life might live beyond Earth

Photos: 2011: Searching for life beyond Earth



"This discovery not only proves the existence of worlds that might be similar to our own but will undoubtedly shape future investigations of exoplanets that could have terrestrial surface environments," the institute said in an announcement Thursday.



After spotting it, the institute wasted no time searching for emissions that could indicate the presence of ETs. So far, no emissions have been found.



The size -- estimated to be 10% larger than Earth -- and distance from its star don't just make for interesting factoids. They give scientists hope that Kepler-186f might sustain life as we know it.



Of nearly 1,800 "confirmed exoplanets" that have been found, approximately 20 orbit their host stars within habitable zones, where it's believed surface water would not freeze or boil. In 2011, NASA announced that Kepler had observed five planets approximately the size of Earth and in the habitable zone.



But the "previously discovered worlds are larger than Earth, and consequently their true nature -- rocky or gaseous -- is unknown," the SETI Institute said in a written announcement on Thursday. "On the basis of the observed dimming of starlight from Kepler-186, the authors estimate that this newly discovered planet is roughly the same size as the Earth."



Theoretical models and observations tell scientists that planets the size of Kepler-186f likely have a composition of iron, rock and ice, like Earth, Quintana told reporters Thursday.



Even if Kepler-186f is rocky, it's not necessarily habitable, scientists warned Thursday. First, a lot would depend on the atmosphere, if it has one, Thomas Barclay of NASA's Kepler mission said. And scientists right now don't have the technology to know what the atmosphere is.



The star's size -- it's an M-dwarf star, smaller and less hot than our sun -- also could come into play. Because it is smaller, the habitable zone is closer, so radiation could prevent life if the atmosphere isn't dense enough, said Victoria Meadows of the University of Washington Virtual Planetary Laboratory.



But the Webb space-based telescope, now under construction, should be able to gather images of planets around closer dwarf stars and study their atmospheres.



Scientists are especially keen about checking dwarf stars because their habitable planets are more easily detectable, and because they are the most abundant type of star in our galaxy, Barclay said.



For researchers, the discovery of Kepler-186f is like a beginning. It's a first but "not a record we wish to keep," Quintana said. "We want to find more of these."



It's likely they will. Astronomers at the University of California, Berkeley, and the University of Hawaii, using data from Kepler, estimate there are tens of billions of Earth-size, possibly habitable planets in our Milky Way galaxy.



CNN's Jason Hanna contributed to this report.

1. About this first:

Theoretical models and observations tell scientists that planets the size of Kepler-186f likely have a composition of iron, rock and ice, like Earth, Quintana told reporters Thursday.

I think they use both size and position of the exoplanet w.r.t. to its star/sun to determine this. Very large planets tend to be gaseous like our Gas Giants past the 4 planets of the inner solar system. The initial exo-planets found were all gas giants, albeit unexpectedly orbiting so close to their suns that they'd have obliterated or flung out (due to their gravity) any smaller rocky inner planets that might have existed. The explanation for gas giants existing so close to their sun was that they were thought to have formed far out in their solar system and then moved their orbit inwards, at which point they'd have knocked out any inner planets. At that early stage in the discovery of planetary systems, Debra Fischer of U of California, Berkeley, some 1.5 decades ago, was determined to seek out planetary systems/solar systems similar to our own: those with gas giants that remained at some distance from the sun, such that inner planets were left unperturbed and intact. These inner planets were then thought to potentially have the conditions necessary to - if not harbour have life as we know it on them - then to create environments we would consider habitable. Scientists are particularly looking for inner planets in that "goldilocks zone" were water can and does exist in its liquid state. Even back then, Debra Fischer had already detected a system with gas giants that were a promisingly significant distance away from its central star/sun, possibly implying the existence of smaller rocky inner planets nearer to that sun. (EOU-3)





2. And about this from the above CNN article:

Even if Kepler-186f is rocky, it's not necessarily habitable, scientists warned Thursday. First, a lot would depend on the atmosphere, if it has one, Thomas Barclay of NASA's Kepler mission said. And scientists right now don't have the technology to know what the atmosphere is.

The star's size -- it's an M-dwarf star, smaller and less hot than our sun -- also could come into play. Because it is smaller, the habitable zone is closer, so radiation could prevent life if the atmosphere isn't dense enough, said Victoria Meadows of the University of Washington Virtual Planetary Laboratory.

But I thought that a decent technique for working out the elemental/molecular composition of a distant planet's atmosphere was already devised by the Greek scientist, Athena Coustenis (of Observatoire de Paris)? Basically, they would use the principle that a solar wind of a sun/star - which consists of magnetically (?) or otherwise energetically charged particles emanating from a sun/star's surface - would blow out some of the atmosphere of any near planetary body into space. The light from the sun would presumably show up the atmospheric "tail" of the planet/its tail will interact with the light from the star or something, and then the astronomers would use the usual method of spectroscopy on the tail/its effect on the star's usual light to work out the tail's elemental/molecular composition, similar to how they analysed starlight itself. (BTP)



- Spectroscopy: With stars, it's easier to work out what they're composed of/what the fuel they're burning is composed of from starlight itself: all light from distant stars/suns that reaches our eyes/telescope is on account of that distant star burning its fuel and thereby producing its light, that we see. Each element [as in periodic table element] burns producing a colour that's at a different part of the light/colour spectrum range. So based on the range of colours of the light that's emitted by a star - including the colours produced after it explodes on death, such as with supernovae - we know what elements a visible star is composed of (which is how we know that the entire universe is made up of elements that we're rather familiar with here on earth, and that said elements originate in stars). (WOU)



- With planets, the problem is that we can't usually *see* exo-planets, that is, we can't see planets of other star (solar) systems. Not even our super telescopes could show us exo-planets since, unlike stars, planets don't *give* off light of their own, obviously, and they're obscured by the glare of their sun/the stars, which stars we do see. This is why detecting planets was by inference: planets exercise gravity on the stars/sun they orbit too, thus causing their sun to "wobble" (CS-C, BTP, EOU, STITU), especially noticeable with larger planets (e.g. Jupiter's gravity causes our Sun to move some IIRC million kilometres off its central position - EOU-3); plus, when a planet passes between our eyeball/telescope and the light of a star we are observing with our telescopes, the light of said star gets diminished due to the obstruction, as you'd expect. A third detection mechanism was that if a planet has atmosphere (as planets do, possibly by definition), then the solar wind of their star/sun will blow some of that atmosphere out into space (BTP-8), the way a comet's tail is caused by the solar wind blowing the comet's water vapour and some of its particles away from the sun's direction, which is why comet's tails are always in the opposite direction to a sun they are near to. Likewise, if a planet is aligned with respect to its sun such that the planet is between us and its star at the moment, then the planet's atmospheric tail will presumably be visible by somehow adding to/interacting with the light of its sun/the distant star. At least, that's as I understand it, since Coustenis was specifically working on using the principle of an atmospheric tail - that's made visible when an exoplanet is in such an alignment - as a means to work out the molecular composition of an exoplanet's atmosphere, again using spectroscopy.



:Or something:



Actually, here - note the following is from ~1.5 decades ago:

But how much can be found out about these other worlds? With Michel Mayor, Athena Coustenis [color="#800080"][Observatoire de Paris][/color] is looking at extraordinary new data from 51 Pegasus [color="#800080"][constellation or something where an early planet discovery was made][/color]. She has developed a new technique that identifies the chemical make-up of the star's planet, something that was previously thought impossible to measure from such a distance.



Michel Mayor: "Three years ago, we had absolutely no idea that we can have access to the chemistry of a planet. Sometimes science is exciting."

Athena Coustenis: "The idea we had was to use the star itself to push forward its planet and tell us something about what its planet is made of."



They cannot see the planet itself, but they can see changes in the light from the star.



Michel: "The interaction between the wind of the star [color="#800080"][its stellar/solar wind][/color] and the atmosphere of the planet create a big tail flowing away from the planet [color="#800080"][similar to comet tails][/color], and IF the line of sight goes through this tail, you have access to the chemistry of the planet."





By analysing the changing spectroscopy of light from the star, they hope to find out exactly what the [color="#FF0000"]atmosphere[/color] of the planet is made of.



(BTP-8)

Since Coustenis and Mayor some 1.5 decades ago already came up with what sounds to me like a reasonable method that could potentially tell us about the chemical composition of an exo-planet's atmosphere, is there a reason that - as per the CNN article further in this post - we don't know much/anything/sufficient info about the promising new planet's atmosphere and how habitable or not it may be for surface-dwelling earthlings?





And the news was:



edition.cnn.com/2014/04/17/tech/space-earth-size-planet/

[color="#0000FF"]NASA discovers Earth-sized planet that may sustain life[/color]



April 18, 2014 -- Updated 0558 GMT (1358 HKT) |



STORY HIGHLIGHTS



[color="#0000FF"]* Researchers find an Earth-sized planet that may be habitable

* It "proves the existence of worlds that might be similar to our own," institute says

* Scientists are looking for emissions that could suggest extraterrestrial life[/color]

* Previously discovered worlds were larger than Earth