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One thousand exoplanets but still no twin for Earth

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#1 Crisp

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Posted 18 October 2013 - 14:28

One thousand exoplanets but still no twin for Earth

 

Any day now, the thousandth exoplanet discovery will be logged, but Earth's twin is not among them. Where are the habitable planets and why can't astronomers find them?

 

Exoplanet-Kepler-20-e-008.jpg

Exoplanet Kepler-20 e was the first rocky planet smaller than Earth discovered orbiting another star. It is too hot to be habitable. Illustration: Nature

 

Imagine Earth's twin planet: shining blue with oceans and laced with white clouds. It orbits a star that is virtually indistinguishable from the sun, and is – of course – teeming with alien life.

The problem is that try as they might, astronomers have not been able to find such a world. Even after two decades of searching, an Earth-sized world, in an Earth-like orbit, around a sun-like star eludes us still.

Jean Schneider at the Observatoire de Paris curates The Extrasolar Planet Encyclopaedia, which currently lists 998 exoplanets. He thinks that the focus on Earth's twin distracts from the real goal. "What we are interested in are habitable planets, even if they are not exactly Earth-like," he says.

 

Yet there are still problems, even after widening the goalposts. The majority of known exoplanets are completely unlike Earth.

They are either too big, or too small, or just too bizarre. Take the case of CoRoT-7b. It is so hot that astronomers theorise it could rain pebbles, which would condense out of the atmosphere in the way water droplets do on Earth.

This is pure speculation, though, because currently there is no way to analyse the atmosphere of most exoplanets. To do so would require a space telescope dedicated to the task, but this is exactly what astronomers could get if the EChO space mission is approved by the European Space Agency (Esa).

EChO is the Exoplanet Characterisation Observatory. At a meeting of the Royal Astronomical Society in London last week, astronomers and engineers discussed the way this mission would work.

It would target stars known to have planets that pass in front of them. The starlight would pass through the atmosphere of those worlds, and the gases there would naturally absorb certain wavelengths of light.

EChO would capture the remaining light, allowing astronomers on Earth to analyse which wavelengths were missing, and hence which gases are present in the planet's atmosphere. If they saw silicon compounds on CoRoT-7b, for example, then the pebble rain might begin to sound a little more plausible.

The EChO technique has been pioneered using ground-based telescopes to look at the biggest and brightest exoplanets. Now, principal investigator Giovanna Tinetti at University College London thinks it is ripe for taking into space. "Now would be the perfect moment for this mission. The next step for exoplanets must be to analyse their atmospheres and we will have several hundred planets to target," she says.

Until now, missions such as Nasa's Kepler Space Telescope have been designed simply to find planets. Together with follow-up observations from ground-based telescopes, they could provide bulk properties such as the planet's mass and diameter, and its orbit.

 

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#2 Soldiers33

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Posted 18 October 2013 - 14:36

There are no more like Earth, becuase God only made one.



#3 spudtrooper

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Posted 18 October 2013 - 14:37

Just a few years ago we had no evidence of how common planetary systems were.



#4 Growled

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Posted 22 October 2013 - 01:28

 

Where are the habitable planets and why can't astronomers find them?

 

I personally believe that life is rare out in the universe. 



#5 Dot Matrix

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Posted 22 October 2013 - 01:34

There are no more like Earth, becuase God only made one.

God didn't make the Earth. Earth was made from accreted rocky debris, which was held together by gravity. 



#6 thomastmc

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Posted 22 October 2013 - 02:25

It's been proven that most stars are solar systems, and there are estimated to be 200-400 billion stars in the galaxy. Our solar system has 8 planets, and other than Earth there's one planet that may have had life, and a moon that may potentially support life.
 
Also, it's very difficult for us to detect most smaller planets, and even more difficult to detect water on them. Most planets we've found are just the massive ones. Huge advances have been made in the last decade, and eventually we will be able to detect smaller planets, and image them with telescopes. Right now though, it's rare.
 

There are likely Earth-like planets out in space, but astronomers must find one within the habitable zone — close enough to its star to have liquid water, but not so close that it’s too hot for life. Already, a dozen planets have been confirmed in the habitable zone, and the Kepler spacecraft used a space telescope to identify 54 more candidates. Habitable zones can move and change with the life of the star, so finding a planet there doesn’t mean it will always be that way.
 
A recent discovery has shown that the star 55 Cancri, 41 light-years away, has a system of five planets, with distributions somewhat similar to the solar system's inner planets (though with much higher masses). [Video: Kepler Reveals Lots of Planets: Some Habitable?]

Most of the planets astronomers have identified don’t resemble Earth. They have characteristics closer to Jupiter or Neptune — gas giants (also known as jovian planets).

Fewer than 5 percent of known exoplanets can be seen directly with telescopes, so astronomers have come up with techniques to find them.

http://www.space.com...exoplanets.html



#7 DocM

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Posted 22 October 2013 - 02:59

I personally believe that life is rare out in the universe.


You are very likely very wrong. Molecular clouds from which stars and planetary systems form are positively loaded with organic compounds, as are carbonaceous chondrite meteorites. Seed these onto a warm, wet environment (under the surface of an icy moon o RR planet etc) and all matter of things happen.

Also look up panspermia.

#8 Growled

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Posted 22 October 2013 - 15:07

You are very likely very wrong. 

 

Probably. It wouldn't be the first time. It's more of a feeling than intellectual knowledge. Until we can prove otherwise it's all just opinion anyway.



#9 Ci7

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Posted 22 October 2013 - 15:13

God didn't make the Earth. Earth was made from accreted rocky debris, which was held together by gravity. 

 

and we got randomly created as humans, NOT!

 

once someone could make new 'biological' creature intelligent life forms then i would throw god/religion out of the windows  until then .....

 

 

...

on the side line 

 

i do believe they are other creatures in the that vast universe. 



#10 Luc2k

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Posted 22 October 2013 - 19:31

and we got randomly created as humans, NOT!

Try reading some biology textbooks. They will blow your mind.



#11 TPreston

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Posted 22 October 2013 - 19:36

The assumption that life needs or even prefers earth like planets is about as arrogant as this

 

There are no more like Earth, becuase God only made one.



#12 Blueclub

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Posted 22 October 2013 - 19:42

The assumption that life needs or even prefers earth like planets is about as arrogant as this

Agreed, we have already seen microbial life living in the depths of the earth, organisms living on volcanic lava, and in super freezing temperatures.

 

Most of the life on Earth needs an Earth-like planet to live outside of Earth, life itself does not.



#13 Jason S.

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Posted 22 October 2013 - 19:48

There are no more like Earth, becuase God only made one.

ohhh i get it. good one.



#14 Andre S.

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Posted 22 October 2013 - 19:53

Even if there is lots of life out there, it's probably so scattered that it's very difficult to find. That said, our discovery of space is at its infancy, so it's much too early to draw conclusions at this point.

 

There are no more like Earth, becuase God only made one.

What makes you think so (assuming this isn't sarcasm)?



#15 psionicinversion

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Posted 22 October 2013 - 20:04

hmmm i was going make a really sarcastic comment but i dont want to risk getting banned again lol