Download NASA Just Discovered Seven New Exoplanets... So What?

Conception de documents L3 Utilisez au mieux le contenu de ce texte, et la vidéo derrière le lien http://webbtelescope.org/video/859/science, pour rédiger un article simple et clair, destiné à de jeunes lecteurs français intéressés par la science. Précisez l’âge de vos lecteurs (entre 10 et 14 ans), ainsi que le support choisi : Science et Vie Junior, Science Illustrée, ou tout autre support adapté. Calibre : une à deux pages du magazine, selon format. Précisez la mise en page de votre article. NASA Just Discovered Seven New Exoplanets...
So What?
Forbes/Science / 2 26 2017 / Hilary Brueck Contributor
On Wednesday, the scientists at NASA kind of freaked out. They announced the discovery of
some seemingly Earth-like planets outside of our solar system, a group of rocky globes
they’re calling ‘TRAPPIST-1.’
How far away are these newly-discovered worlds? They’re about 40 light years from Earth.
That means using today’s rocket technology (and a whole lot of cash), it would probably take
about 11,250 years to get to TRAPPIST-1.
This Week: We found 7 Earth-sized planets orbiting a dwarf star, 3 of them in the habitable
zone! Also, @NASA_SLS rocket test & more! Watch: pic.twitter.com/cBBerkelU1
— NASA (@NASA) February 25, 2017
I called up one of NASA’s exoplanet experts, Aki Roberge, to help us break down the find. A
specialist in planet formation, Roberge helps plan future missions for NASA, and confirms
that the space agency nerds are just about “as excited as we get” about TRAPPIST-1.
Here are 5 reasons why:
Q: Why Are Scientists Freaking Out About TRAPPIST-1?
Roberge: To be completely blunt, the most exciting thing for actual scientists is that these
planets are close enough that we’re actually going to be able to study them – particularly
when the James Webb Space Telescope launches (October 2018.) When that launches, it will
have a real shot at actually taking a look at the atmospheres of these planets – or if they have
atmospheres at all. So it’s like a promise of future excitement, in some ways.
I can see why people would think this is more of the same stuff [NASA's] already been doing.
And in some aspects, it is. But it’s a smaller star, it’s closer to us, and it’s got more planets –
really tightly packed. The closer the system is to our solar system – the more the star is like
the Sun and the planet is like the Earth, the more likely we are to understand what we’re
looking at. That’s what makes it exciting.
Q: Why is everyone calling these planets ”Earth-like?’
Roberge: At the moment, all you really tell from the transits is these are small black dots. We
just get a radius – and if we’re super lucky – as they were in the case of this system, they can
get masses. The sizes and masses of these planets is really valuable information though,
because it does suggest that most of them are rocky. Six of the seven planets look like they’re
rocky. And being Earth-sized, we think it’s a good place: an atmosphere thick enough to keep
you warm and last for billions of years, but not so thick that you end up being a gas giant
planet.
There are, however, several reasons to think that being a rock in the habitable zone of a red
dwarf star is not actually a nice place to live, and that those environments are very different
from our solar system. A lot of these investigations that are going forward over the next
decade are to find the answers to these questions.
The TRAPPIST-1 star
has seven Earth-size
planets orbiting it. This
artist’s concept appeared
on the cover of Nature
on Feb. 23, 2017.
(Credit:
NASA/JPLCaltech)
Q: Is there water on
the surface of these
planets?
Roberge: Most of them
are the right distance
from a star that maybe
they could have liquid water on their surfaces. But that’s a huge maybe. Just look at our solar
system: we have three rocky planets – about the size of the TRAPPIST-1 planets. We’ve got
Earth, Venus and Mars in or near what astronomers call the “habitable zone” – and they
couldn’t be more different!
Q: What’s the big deal about ‘rocky’ planets?
Roberge: As far as we know, that’s the only kind of planet that we could have habitable
conditions of life on – life that we could actually understand or recognize from interstellar
distances. The Earth is unique in the solar system in one really important way: it’s the only
planet that has surface life so abundant that it’s affecting the atmosphere. That is noticeable
from interstellar distances. So it’s not really that we think Earth-like life is the only life that
can be out there. It’s just the only life we can detect.
Q: What can non-scientists get excited about here?
Roberge: I think this would really bring it home to people that we have neighbors. I think a
lot of people are used to thinking “oh, exoplanets, those are all really distant.” As far as the
laws of physics go, you could get to TRAPPIST-1 in a human lifetime (~40 years traveling at
the speed of light). So it becomes more of an engineering problem than a laws of physics
problem.
Exoplanet discovery: What does Nasa's
announcement mean - and should we be excited
about TRAPPIST-1?
•
Chiara Palazzo / The Telegraph / 24 February 2017
Turns out it wasn’t just dust on the telescope lens, Nasa astronomers have spotted seven
Earth-size planets around a nearby star, some or all of which could harbour water and
possibly life.
Google has marked the Earth-shattering discovery with a Doodle, featuring the seven planets
squeezing into view on the earth's telescope.
What is TRAPPIST-1?
TRAPPIST-1 stands for
Transiting Planets and
Planetesimals Small
Telescope. The discovery is
a small, dim star in the
constellation Aquarius, less
than 40 light-years from
Earth, or 235 trillion miles
away, according to Nasa and
the Belgian-led research
team who announced its
discovery on Wednesday.
An artist's conception of what the surface of the exoplanet TRAPPIST-1f may look like
Seven planets circle Trappist-1, with orbits ranging from one and a half to 20 days. If
Trappist-1 were our sun, all these planets would fit inside the orbit of Mercury. That's how
close they are to their star and why their orbits are so short. The planets have no real names.
They're only known by letters, "b" through "h." The letter "A" refers to the star itself.
Can this newly discovered solar system support life?
Six of TRAPPIST-1's "exoplanets" lie in a temperate zone where surface temperatures range
from zero to 100C. Of these, at least three are thought to be capable of having watery oceans,
greatly increasing the likelihood of life. No other star system known contains such a large
number of Earth-sized and probably rocky planets.
All are about the same size as Earth or Venus, or slightly smaller. Because the parent star is so
dim, the planets are warmed gently despite having orbits much smaller than that of Mercury,
the planet closest to the sun. Scientists said they need to study the atmospheres before
determining whether these rocky, terrestrial planets could support some sort of life.
What do the planets and solar system look like?
As well as being in tight orbits, the TRAPPIST-1 planets are unusually close to one another,
conjuring an image straight out of science fiction. If Trappist-1 were our sun, all seven planets
would be inside Mercury's orbit. Mercury is the innermost planet of our own solar system.
How did they find out about TRAPPIST-1?
The discovery, reported in the journal Nature, was made by astronomers using Nasa's
exoplanet-hunting Spitzer Space Telescope. The telescope operates at the infrared
wavelengths which glow brightest from TRAPPIST-1, and can detect the tiny dimming that
occurs when a passing or "transiting" planet blocks out light from its star. Spitzer's data
allowed the team to measure precisely the sizes of the seven planets and estimate the masses
and densities of six of them.
The Spitzer was launched in 2003, and was never meant to continue in space for this long but
the telescope is still making discoveries beyond what was imagined. It follows the earth's
orbit around the sun, but travels slightly slower, so over time it gets further away from the
earth. It is now in its "final" phase, which lasts until 2018.
What is an exoplanet anyway?
An exoplanet is any planet that is outside of our solar system - ie anything that is not orbiting
our star. The first exoplanet was discovered in 1988, but over 3,500 have been discovered
since then. Only a tiny fraction of these have been deemed capable of supporting life in any
way. Oceans and closeness to a star are two factors that scientists take into account.
What next?
Scientists need to study the atmospheres of these almost assuredly rocky planets before
drawing any conclusions about water and life. The Hubble Space Telescope already is on the
case and the still-under-construction James Webb Space Telescope will join in once it's
launched next year. The Webb will search for gases that might be a byproduct of life: oxygen,
ozone and methane. Scientists say it should take five years to get a handle on all these
atmospheres, and figure out whether water - and maybe life - are present.
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http://webbtelescope.org/video/859/science
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Pictures of space and planets :
http://www.independent.co.uk/news/science/exoplanet-discovery-nasa-pictures-posters-lifetrappist-1-solar-system-announcement-a7594826.html