Kepler telescope spies 'most Earth-like' worlds to date

Artist's impression of Kepler-62 system Artist's impression: The outermost pair are the smallest exoplanets yet found in a host star’s habitable zone

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The search for a far-off twin of Earth has turned up two of the most intriguing candidates yet.

Scientists say these new worlds are the right size and distance from their parent star, so that you might expect to find liquid water on their surface.

It is impossible to know for sure. Being 1,200 light-years away, they are beyond detailed inspection by current telescope technology.

But researchers tell Science magazine, they are an exciting discovery.

"They are the best candidates found to date for habitable planets," stated Bill Borucki, who leads the team working on the US space agency Nasa's orbiting Kepler telescope.

The prolific observatory has so far confirmed the existence of more than 100 new worlds beyond our Solar System since its launch in 2009.

The two now being highlighted were actually found in a group of five planets circling a star that is slightly smaller, cooler and older than our own Sun. Called Kepler-62, this star is located in the Constellation Lyra.

The two planets go by the names Kepler-62e and Kepler-62f

Its two outermost worlds go by the names Kepler-62e and Kepler-62f.

They are what one might term "super-Earths" because their dimensions are somewhat larger than our home planet - about one-and-a-half-times the Earth's diameter.

Nonetheless, their size, the researchers say, still suggests that they are either rocky, like Earth, or composed mostly of ice. Certainly, they would appear to be too small to be gaseous worlds, like a Neptune or a Jupiter.

Many assumptions

Planets 62e and 62f also happen to sit a sufficient distance from their host star that they receive a very tolerable amount of energy. They are neither too hot, nor too cold; a region of space around a star sometimes referred to as the "Goldilocks Zone".

Kepler Mission

An illustration of Kepler
  • Launched in 2009, the Kepler space telescope is on a mission to find Earth-like worlds orbiting distant stars
  • It works by detecting periodic variations in the brightness of stars caused by orbiting exoplanets passing in front of them
  • In January 2013, astronomers used Kepler's data to estimate that there are at least 17 billion Earth-sized exoplanets in the Milky Way Galaxy

Given the right kind of atmosphere, it is therefore reasonable to speculate, says the team, that they might be able to sustain water in a liquid state - a generally accepted precondition for life.

"Statements about a planet's habitability always depend on assumptions," said Lisa Kaltenegger, an expert on the likely atmospheres of "exoplanets" and a member of the discovery group.

"Let us assume that the planets Kepler-62e and -62f are indeed rocky, as their radius would indicate. Let us further assume that they have water and their atmospheric composition is similar to that of Earth, dominated by nitrogen, and containing water and carbon dioxide," the Max Planck Institute for Astronomy in Heidelberg researcher went on.

"In that case, both planets could have liquid water on their surface: Kepler-62f gets less radiation energy from its host star than the Earth from the Sun and therefore needs more greenhouse gases, for Instance more carbon dioxide, than Earth to remain unfrozen.

"Kepler-62e is closer to its star, and needs an increased cloud cover - sufficient to reflect some of the star's radiation - to allow for liquid water on its surface."

Key signatures

None of this can be confirmed - not with today's technology. But with future telescopes, scientists say it may be possible to see past the blinding glare of the parent star to pick out just the faint light passing through a small world's atmosphere or even reflected off its surface.

This would permit the detection of chemical signatures associated with specific atmospheric gases and perhaps even some surface processes. Researchers have spoken in the past of trying to detect a marker for chlorophyll, the pigment in plants that plays a critical role in photosynthesis.

Dr Suzanne Aigrain is a lecturer in astrophysics at the University of Oxford.

She said ground-based experiments and space missions planned in the next few years would give more detailed information on distant planets like those announced by the Kepler team.

Astronomers would like to pin down the masses of the planets (information difficult to acquire with Kepler), as well as getting that data on atmospheric composition.

Dr Aigrain told BBC News: "What we do next is we try to find more systems like these; we try to measure the frequency of these systems; and we try to characterise individual systems and individual planets in more detail.

"That involves measuring their masses and their radii, and if possible getting an idea of what's in their atmospheres. But this is a very challenging task."

Kepler meanwhile will just keep counting planets beyond our Solar System.

It is equipped with the largest camera ever launched into space. It senses the presence of planets by looking for a tiny "shadowing" effect when one of them passes in front of its parent star.

Planets graphic and follow me on Twitter: @BBCAmos


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  • rate this

    Comment number 54.

    In other words, you need a miracle, or a designer..
    Or sheer numbers and chaos theory.
    Much more likely. They can be proven for a start.

  • rate this

    Comment number 53.

    Now all we need is for Zephram Cochrane to invent the Warp drive...

  • rate this

    Comment number 52.

    Fascinating as it is, maybe we should sort our own planet out before we go and mess up someone elses.

  • rate this

    Comment number 51.

    It would take about 10,000 years to get to our nearest neighbouring planetary system. So don't hold your breath for human colonization of space. It will never happen.
    Its best we start looking after our own planet and stop dumping pollution and toxic waste every where.

  • rate this

    Comment number 50.

    The amount of carbon to support life was only produced around 3.5 billion years ago.Life then started its long climb. If this is the case then to get to intelligent life in the Universe it must take about the same time throughout. We may be one of the most advanced races in the Universe, so no radio signals to be picked up. Shame for the SETI people, searching for what yet may not yet be there:o)

  • rate this

    Comment number 49.

    I can't wait to check out Google Kepler 62e/f.

  • rate this

    Comment number 48.

    All very interesting, but how much money is being wasted searching for life on other planets that would be better spent caring for life on our own planet?

  • rate this

    Comment number 47.

    @40 I always wanted to go to the "planet of the gingers".
    @36 A C Clarke used to talk about the gaseous creatures that lived in Jupiter's atmosphere.

    I will not fear, fear is the mind-killer.

  • rate this

    Comment number 46.


    Very true, and the planet needs a large planet or two to gravitationlly attract/divert all those comets/asteroids in to orbits that don't intersect this 'Earth like' planet.

    Also the planet needs an ozone layer, it also needs radiation belts, it also needs a decent size moon, an liquid iron core and rotate in a way to provide seasons.

    In other words, you need a miracle, or a designer..

  • rate this

    Comment number 45.

    I loved all this stuff during Physics Lessons at school. It's just a shame they only spent a few lessons on space and so much time teaching less interesting things like binary and conducting pointless experiments like dropping ping pong balls and recording their rate of decent (without any technology other than eye-site and a stop watch).

  • rate this

    Comment number 44.

    Interesting? Yes for many. Exciting? Yes for many. Useful, not convinced save we do it because we can and it is there. Life forms that do not need oxygen and water ..almost certainly albeit not on current beliefs but again at one time the sun went around the earth.

  • rate this

    Comment number 43.

    It's all fascinating and intriguing stuff, to eventually find life on other earth like planets, but to think that one day humans would make a home there, think again. It would require technology beyond human means to travel there, even utilising the power of the sun. At least we'll be able to spy on them big brother styley without them knowing, who knows they might be spying on us now.

  • rate this

    Comment number 42.

    I guess the scientists themselves are mainly interested in finding planets. You learn a lot about the origins of a solar system (including our own) by seeing what kinds of planets orbit it.
    Then again, there's some sensible reasoning. To find my keys I COULD look where I don't expect to find them. Then again, I may as well start by looking where I think they'll probably be.

  • rate this

    Comment number 41.

    Paul. You look for Earth like planets because you know for a fact that Earth like planets can support life, other types of planets are still unknown, so looking for Earth like planets is the most sensible course of action.

  • rate this

    Comment number 40.

    ..We would create an artificial wormhole to jump through so that we arrive in orbit around this planet in an instant...
    Possibly; or just go and buy some 'melange' (I'm sure Tesco will have it - no need to go to Arrakis) and then just fold space. Or wait for the Virgin Spacing Guild to offer excursions.

  • rate this

    Comment number 39.

    @ 27

    Creator of an icy, inhospitable vacuum...

    Sure it wasn't my wife?

  • rate this

    Comment number 38.


    They used to say it was impossible to fly too...

    Learn to dream - who knows how fast spaceships will be able to go in a thousand years time ? Even if we can't break the lightspeed barrier we could still cross large distances to this planet using "generation starships". The journey could also be broken up into stages by colonising closer planets to earth first...

  • rate this

    Comment number 37.

    We'll never be able to go to this planet even at light speed it seems. But who knows, another few centuries of scientific advancement (if we don't kill each other over politics or sky fairies before then) and we might have faster than light travel. Just look at how far technology has come in the last 100yrs, imagine another 2 centuries or so of that kind of rapid advancement.

  • rate this

    Comment number 36.

    Why are we looking for Earth like worlds to find life??? I find it astonishing to think that scientists are so short sighted as to think that life can only be supported where there is oxygen and water. I would lay my mortgage on the fact that there are life forms (even intelligent life forms) existing where water and oxygen would to toxic to them.

  • rate this

    Comment number 35.

    So what? - I mean really.. so what? This little green man thing is a silly issue that science uses to keep us interested and keep our hands in our pockets for the real (and unsexy)science that is going on. can we leave the silly dumbed down stuff to the tabloids


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