How can thenew planet that like 'earth' that they just discovered have same temperatures as ours when.........

Question

A) the suns alot bigger than ours and B) the planets closer to the sun???????????

Peter k i read it in todays daily mail mate

Answer 1

Would you like to add a link to a website about this new planet. I haven't heard about this discovery?

The only small planet outside our solar system that I know has been discovered is 5 times the size of earth and is very cold, like -220C
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OK, the news travels slow around here and I now have a good link to it. As the others said, a red star is a lot less hot so that will compensate for the planet being much closer.

Answer 2

As regards the question: red dwarf stars are Class M and the photosphere temperature of a Class M star is in the range 2000 - 3500 K (highest for M0 stars, least for M9 stars. This particular star is M2.5 and that makes its photospheric temperature about 3100 K.)

The Sun is in Class G whose photosphere temperatures lie in the range 5,000 to 6,000 K (highest for G0 stars, least for G9 stars) The Sun is G2 so that makes it about 5,800 K.

The habitable zone where temperatures are comfortable and water will be between freezing and boiling point is therefore closer to a cooler star than a warmer one. If Gliese 581 c were the same distance from its star as we are from Sol it would be too cold.

But you are wrong when you say that
Gliese 581 (the star) is a lot bigger than Sol. Class M stars are typically 0.3 of the mass and 0.4 of the radius of Sol. (40% of the radius = 6.4 % of the volume.)

For Peter K

The confusion is understandable given both are red dwarf stars and both have a planet about 5 times the mass of earth.

The links you want to the new discovery of April 23rd 2007 are:

http://en.wikipedia.org/wiki/Gliese_581_c
http://en.wikipedia.org/wiki/Gliese_581

The planet you are thinking of is 21,500 light years away and is called OGLE-2005-BLG-390Lb

On January 25, 2006 the discovery of OGLE-2005-BLG-390Lb was announced. This is the most distant and probably the coldest exoplanet found to date. It is believed that it orbits a red dwarf star around 21,500 light years from Earth, towards the center of the Milky Way galaxy.

It was discovered using gravitational microlensing, and is estimated to have a mass of 5.5 times that of Earth, making it (in 2006) the least massive known exoplanet to orbit an ordinary main-sequence star.

Prior to this discovery, the few known exoplanets with comparably low masses had only been discovered on orbits very close to their parent stars, but this planet is estimated to have a relatively wide separation of 2.6 AU from its parent star

Answer 3

If the sun is red, it is cooler, so a planet can be closer, and still be the same temperature as us.

Answer 4

Dwarf reds are cooler burning than our sun.

Answer 5

it's a red drawf.... they are much cooler than our sun.. that's y all the factors cancel out and the temp is around the same..