To: Hawkmoon who wrote (38573 ) 2/27/2013 4:05:38 PM From: miraje 2 Recommendations Read Replies (1) | Respond to One day her Sun Sister will burn Gaia to a crisp in a Supernova.. en.wikipedia.org supernova . Instead, in about 5 billion years, it will enter a red giant phase. Its outer layers will expand as the hydrogen fuel at the core is consumed and the core will contract and heat up. Hydrogen fusion will continue along a shell surrounding a helium core, which will steadily expand as more helium is produced. Once the core temperature reaches around 100 million kelvin , helium fusion at the core will begin producing carbon, and the Sun will enter the asymptotic giant branch phase. [41] Following the red giant phase, intense thermal pulsations will cause the Sun to throw off its outer layers, forming a planetary nebula . The only object that will remain after the outer layers are ejected is the extremely hot stellar core, which will slowly cool and fade as a white dwarf over many billions of years. This stellar evolution scenario is typical of low- to medium-mass stars. [108] [109] AU (1.5×1011 m ), 250 times the present radius of the Sun. [110] When the Sun is an asymptotic giant branch star, it will have lost roughly 30% of its present mass due to a stellar wind, so the orbits of the planets will move outward. If it were only for this, Earth would probably be unaffected. However, new research suggests that Earth will be swallowed by the Sun owing to tidal interactions. [110] If Earth should escape incineration in the Sun, its water will be boiled away and most of its atmosphere will escape into space. During its life in the main sequence , the Sun is becoming more luminous (about 10% every 1 billion years) and its surface temperature is slowly rising. The Sun used to be fainter in its early past. The increase in solar temperatures is such that in about another billion years the surface of the Earth will probably become too hot for liquid water to exist, ending all terrestrial life. [110] [111]
