whats the new planet?

Question

hi

Answer 1

GLIESE 581c

This newly-discovered planet where life is thought to be feasible orbits Gliese 581, one of the nearest 100 stars to us, 20.4 light years away.

The new planet was found on 23rd April 2007 by a team led by Stephane Udry of Geneva University, The observatory they used was high in the Chilean Andes, where good viewing conditions would be available.

It is in the constellation Libra. It is the 87th closest star system to us. Its star (a Red Dwarf) is too faint to be seen with the naked eye, however. Its magnitude is 11.56.

What is unusual about Gliese 581c, amongst the 241 planets we have found orbiting other stars is

a) it is a rocky terrestrial planet not a gas giant

b) it is in the habitable zone i.e. with a temperature range at which water would be a liquid not ice. This is felt to be essential if it is to harbour life.

c) it has a radius 1.5 times that of earth (and a mass 5 x earth), the smallest yet,

(d) It orbits very close to its star (as the star, a Red Dwarf, is much cooler than our Sun, the planet needs to be nearer in to be warm enough to be habitable) and its year is a mere 13 Earth days in length.

There are two other planets in the same stellar system, one even further in (Gliese 581 b) a Neptune-sized planet of 17 Earth masses found in 2005 and one further out (Gliese 581 d) a planet of 8 Earth masses found in 2007.

The big question marks are:

(a) it is big enough to retain an atmosphere but is it breathable by humans?

(b) does it actually have (a plentiful supply of) water?

(c) how would we get there? (our present fastest rockets available would take 300,000 years)

(d) is the planet gravitationally locked to ts star, such that the same side of it always faces the star?

Many of the questions people will inevitably ask can only be answered when we can send an unmanned probe there. Meanwhile other planets will be found even nearer to us. (We know of a planet 10.5 light years away around Epsilon Eridani (the 9th nearest star) and 3 around Gliese 876, 15 light years away.)

Wilhelm Gliese was a German astronomer, best known for the Gliese Catalogue of Nearby Stars that he compiled.

Answer 2

Gliese 581c is now an "old" planet. At least a couple of dozen new planets have been discovered since it was announced a few weeks ago. This is the way it's going to be as the search for extrasolar planets goes on in earnest.

I don't think most people realise that there's been a fundamental shift in the last 10 years. Prior to this, planets were only known in our own solar system, and new discoveries were very rare. This changed about 10 years ago as we began to discover large faint bodies in the outer reach of our solar system (such as Sedna and Eris), at the same time as we developed techniques sensitive enough to detect planets around other stars. This started a rapid increase in the number of planets, so that their discovery has become an everyday occurrence. The researchers more aware of PR get media publicity for their discoveries, usually by differentiating them from the horde of new planets in some way. But to astronomers, the whole subject of new planets has become somewhat boring. The new discoveries are all so far away that we have little chance of ever seeing them, let alone visiting them.

A side effect of this was the growing realization among astronomers that Pluto really was no more important in our solar system than any of these new discoveries, which is the real reason why it got "demoted".

Answer 3

Gliese 581 C

Answer 4

Hi. Johnny is correct. http://en.wikipedia.org/wiki/Gliese_581_c