This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.
You can find the current article at its original source at http://www.bbc.co.uk/news/science-environment-30705517
The article has changed 4 times. There is an RSS feed of changes available.
| Version 1 | Version 2 |
|---|---|
| 'Alien Earth' is among eight new far-off planets | 'Alien Earth' is among eight new far-off planets |
| (about 5 hours later) | |
| One of eight new planets spied in distant solar systems has usurped the title of "most Earth-like alien world", astronomers have said. | |
| All eight were picked out by Nasa's Kepler space telescope, taking its tally of such "exoplanets" past 1,000. | All eight were picked out by Nasa's Kepler space telescope, taking its tally of such "exoplanets" past 1,000. |
| But only three sit safely within the "habitable zone" of their host star - and one in particular is rocky, like Earth, as well as only slightly warmer. | But only three sit safely within the "habitable zone" of their host star - and one in particular is rocky, like Earth, as well as only slightly warmer. |
| The find was revealed at a meeting of the American Astronomical Society. | The find was revealed at a meeting of the American Astronomical Society. |
| Red sky | Red sky |
| The three potentially habitable planets join Kepler's "hall of fame", which now boasts eight fascinating planetary prospects. | The three potentially habitable planets join Kepler's "hall of fame", which now boasts eight fascinating planetary prospects. |
| And researchers say the most Earth-like of the new arrivals, known as Kepler 438b, is probably even more similar to our home than Kepler 186f - which previously looked to be our most likely twin. | And researchers say the most Earth-like of the new arrivals, known as Kepler 438b, is probably even more similar to our home than Kepler 186f - which previously looked to be our most likely twin. |
| At 12% larger than Earth, the new claimant is bigger than 186f but it is closer to our temperature, probably receiving just 40% more heat from its sun than we do from ours. | At 12% larger than Earth, the new claimant is bigger than 186f but it is closer to our temperature, probably receiving just 40% more heat from its sun than we do from ours. |
| So if we could stand on the surface of 438b it may well be warmer than here, according to Dr Doug Caldwell from the Seti (Search for Extra-Terrestrial Intelligence) Institute in California. | So if we could stand on the surface of 438b it may well be warmer than here, according to Dr Doug Caldwell from the Seti (Search for Extra-Terrestrial Intelligence) Institute in California. |
| "And it's around a cooler [red dwarf] star... so your sky would look redder than ours does to us," Dr Caldwell said. | "And it's around a cooler [red dwarf] star... so your sky would look redder than ours does to us," Dr Caldwell said. |
| That first-person encounter, however, is unlikely - both because the planet is 475 light years away and because we still have essentially no idea what it's made of. | That first-person encounter, however, is unlikely - both because the planet is 475 light years away and because we still have essentially no idea what it's made of. |
| Images from the Kepler telescope, which trails behind the Earth and peers far into the distance as we orbit our own sun, are used to identify far-off planets by observing "transits". | Images from the Kepler telescope, which trails behind the Earth and peers far into the distance as we orbit our own sun, are used to identify far-off planets by observing "transits". |
| This refers to the dimming of a star's light when a planet passes in front of it. | This refers to the dimming of a star's light when a planet passes in front of it. |
| A large team of researchers then uses additional data from earth-bound telescopes to further explore these unfamiliar solar systems. | A large team of researchers then uses additional data from earth-bound telescopes to further explore these unfamiliar solar systems. |
| They try to calculate how big the planets are, and how closely they orbit their host stars. | They try to calculate how big the planets are, and how closely they orbit their host stars. |
| Not everything that causes such a dimming eventually turns out to be a planet, however. | Not everything that causes such a dimming eventually turns out to be a planet, however. |
| At the same time as the eight confirmed new exoplanets were announced by a 26-strong team spanning Nasa and multiple US institutions, the Kepler mission's own scientists released another tranche of more than 500 "candidate" planets. | At the same time as the eight confirmed new exoplanets were announced by a 26-strong team spanning Nasa and multiple US institutions, the Kepler mission's own scientists released another tranche of more than 500 "candidate" planets. |
| "With further observation, some of these candidates may turn out not to be planets," said Kepler Science Officer Fergal Mullally. | "With further observation, some of these candidates may turn out not to be planets," said Kepler Science Officer Fergal Mullally. |
| "Or as we understand their properties better they may move around in, or even outside, the habitable zone." | "Or as we understand their properties better they may move around in, or even outside, the habitable zone." |
| 'Star Trek' scenario | 'Star Trek' scenario |
| Even once scientists have anointed a candidate as a confirmed exoplanet, the question of whether or not it is "Earth-like" is a fraught one, with fuzzy boundaries. | Even once scientists have anointed a candidate as a confirmed exoplanet, the question of whether or not it is "Earth-like" is a fraught one, with fuzzy boundaries. |
| The size of the habitable or "Goldilocks" zone, where a planet is far enough from its sun to hold water but not so distant that it freezes, depends on how confident scientists want to be with their guess-work. | The size of the habitable or "Goldilocks" zone, where a planet is far enough from its sun to hold water but not so distant that it freezes, depends on how confident scientists want to be with their guess-work. |
| According to Dr Cardwell, just three of the eight new exoplanets can be confidently placed in that zone - and only two of those are probably rocky like the Earth. | According to Dr Cardwell, just three of the eight new exoplanets can be confidently placed in that zone - and only two of those are probably rocky like the Earth. |
| More detailed description is very difficult. | More detailed description is very difficult. |
| "From the Kepler measurements and the other measurements we made, we don't know if these planets have oceans with fish and continents with trees," Dr Caldwell told BBC News. | "From the Kepler measurements and the other measurements we made, we don't know if these planets have oceans with fish and continents with trees," Dr Caldwell told BBC News. |
| "All we know is their size and the energy they're receiving from their star. | "All we know is their size and the energy they're receiving from their star. |
| "So we can say: Well, they're of a size that they're likely to be rocky, and the energy they're getting is comparable to what the Earth is getting. | "So we can say: Well, they're of a size that they're likely to be rocky, and the energy they're getting is comparable to what the Earth is getting. |
| "As we fill in these gaps in our solar system that we don't have, we learn more about what it means to be Earth-like, in some sense." | "As we fill in these gaps in our solar system that we don't have, we learn more about what it means to be Earth-like, in some sense." |
| Speaking at a related event at the conference, Prof Debra Fischer from Yale University said she remembered a time before the first exoplanet was discovered, more than two decades ago. | Speaking at a related event at the conference, Prof Debra Fischer from Yale University said she remembered a time before the first exoplanet was discovered, more than two decades ago. |
| "I remember astronomers before that point being very worried," she said. | "I remember astronomers before that point being very worried," she said. |
| "We really had to step back and say: Maybe the Star Trek picture is wrong. That filled me with despair." | "We really had to step back and say: Maybe the Star Trek picture is wrong. That filled me with despair." |
| Prof Fischer said that sensitive telescopes like Kepler had ushered in an era of "amazing and impressive work". | Prof Fischer said that sensitive telescopes like Kepler had ushered in an era of "amazing and impressive work". |
| "We're talking about a planet - and we can only see its star with a powerful telescope. | "We're talking about a planet - and we can only see its star with a powerful telescope. |
| "And we can draw graphs and sketch its composition and have serious scientific discussions. This is incredible." | "And we can draw graphs and sketch its composition and have serious scientific discussions. This is incredible." |
| Follow Jonathan on Twitter. | Follow Jonathan on Twitter. |