First Rocky Exoplanet Confirmed

Matt_dk writes "The confirmation of the nature of CoRoT-7b as the first rocky planet outside our Solar System marks a significant step forward in the search for Earth-like exoplanets. The detection by CoRoT and follow-up radial velocity measurements with HARPS suggest that this exoplanet has a density similar to that of Mercury, Venus, Mars and Earth, making it only the fifth known terrestrial planet in the Universe. The search for a habitable exoplanet is one of the holy grails in astronomy. One of the first steps towards this goal is the detection of terrestrial planets around solar-type stars. Dedicated programs, using telescopes in space and on ground, have yielded evidence for hundreds of planets outside of our Solar System. The majority of these are giant, gaseous planets, but in recent years small, almost Earth-mass planets have been detected, demonstrating that the discovery of Earth analogues — exoplanets with one Earth mass or one Earth radius orbiting a solar-type star at a distance of about 1 astronomical unit — is within reach."

Not really the first

[EdZ]

Smallest maybe, and the first to have a confirmed radius value, but hardly the first rocky exoplanet discovered. PSR 1257+12 [extrasolar.net] wins by about 18 years.

For those interested in details..

[gzipped_tar]

Here's a scientific paper describing how the period/mass/size/etc of the planet was deduced from observation data: http://arxiv.org/abs/0908.0241 [arxiv.org]

According to the paper, this planet's orbital semimajor axis (or in plain English, the "average" distance from the planet to the sun) is about 0.0172 astronomical units. Since its sun's temperature is roughly at the level of our Sun (also in the paper), it means the planet is probably a hell much hotter than the Earth...

Re:For those interested in details..

[gzipped_tar]

And this one for a discussion about its possible composition and origin: http://arxiv.org/abs/0907.3067 [arxiv.org]

Re:By the time we get there

[thisnamestoolong]

Well, this planet in particular will never be able to support life as it is only about 2.5 million km from its parent star (which is about 23 times closer than Mercury is to our parent star, aka the Sun). Being this close, the planet is likely tidally locked like our moon, meaning that one side of the planet always faces the star. This would make the day side of the planet lava and the night side akin to one of the moons of Saturn (assuming, of course, that there is no atmosphere, which is an exceedingly reasonable assumption to make given the proximity to the star). That means that this planet never was, and never will be, capable of sustaining anything that we know of to be life.

As planets which could be habitable -- when you speak of the time we actually get to these planets, we are only talking in terms of thousands or tens of thousands of years. These measures of time are beyond insignificant in geological time and would have next to no impact on habitability (barring, of course, sudden events such as asteroid impacts, nearby supernovae, wandering black holes, etc.) -- if it is not yet habitable you can't really count on that changing too much in the next ten thousand (or ten million for that matter) years.

Re:You are forgetting to account of GR

[DirePickle]

1. That's Special Relativity.

2. .5c only gives a gamma of 1.15--for the traveler the apparent travel time is divided by 1.15.

3. If we assume that the other star is not moving at an appreciable percentage of the speed of light with respect to Earth (I believe this is a safe bet for pretty much any star in our own galaxy--the sun moves at .2c with respect to the rest frame of the MWG) then if Earth sees our ship hop up to .5c, that's how fast the other star will see it going, also.