Smallest Planet Outside Our Solar System Found 91
mikkl666 writes "Following the recent story about the discovery of the youngest planet outside our solar system, Spanish researchers now report that they found the smallest exoplanet observed so far. The planet, known as GJ 436c, was found by analyzing distortions in the orbit of another, larger planet, and its radius is only about 50 percent greater than the Earth's. The scientists are confident that their new method will lead to a series of further discoveries: 'I think we are very close, just a few years away, from detecting a planet like Earth.' You can also reference the the original paper online for further details."
The article is wrong (Score:5, Informative)
What they mean to say is that this seems to be the lowest mass planet found orbiting a main-sequence star.
It's also annoying that the press release quotes the radius of the planet (which cannot be measured, and is only an approximation based on guesses at density), when what they actually measured is the mass. Planetary densities vary widely; they have no idea what the radius is.
Re:planet definition (Score:3, Informative)
what is the minmum possible size/mass of a planet according to the new definition of 'planet'?
I don't know about that (well I do know but you could just look it up) but if a planet 4.7 times as heavy and 50% bigger than Earth was considered too small/lightweight to be considered a planet I'd seriously consider packing my bags and moving to a real planet like Uranus (to live in an airship of some sort that is, I'm very aware that you can't actually stand on Uranus, thank you!).
Re:The article is wrong (Score:4, Informative)
http://www.badastronomy.com/bablog/2008/04/10/no-its-not-the-smallest-exoplanet-found/ [badastronomy.com]
Re:The article is wrong (Score:5, Informative)
Re:The article is wrong (Score:4, Informative)
From the article:
From wikipedia article on Gliese 581c [wikipedia.org]:
It seems like it may be a little premature to assume that the new planet is the smallest, even when comparing to planets around main-sequence stars.
I agree the radius is probably a made up number.
Scientist: "Assuming a density similar to earth's, the radius of the planet would be 50% greater than Earth's."
Science reporter: "The planet's radius is 50% greater than Earth's."
Re:planet definition (Score:2, Informative)
It's not really confirmed... (Score:5, Informative)
In reality... (Score:3, Informative)
Lets say it needs to be about the size of mercury and sweep the question under the rug as frankly a ball of water the size of a basketball, if the only object orbiting a star, would qualify as a planet.