JACKSON LAKE, WYOMING—The world may not end on 21 December 2012, as predicted by some doomsayers, but one thing is certain: Earth won’t be around forever. Astronomers at the Extreme Solar Systems II conference here, who study the birth and evolution of planetary systems, are also coming to grips with the ultimate fate of planets like our own. And although Earth’s own future isn’t too bright, it looks like our planet could possibly reincarnate as a new world.
At the end of their lives, massive stars much larger than the sun detonate as supernovae, hurling most of their planets into deep space in the process. Recently, some researchers even claimed to have detected such rogue planets. But stars like our sun swell into bloated red giants when the nuclear fuel in their cores is depleted. As a result, some 5 billion years from now, the sun will engulf the inner planets, Mercury and Venus.
According to theoretical physicist Eva Villaver of the Universidad Autónoma de Madrid in Spain, it’s unclear whether Earth will survive this phase. “It’s a tricky question,” she says. If the sun loses much of its outer layers into space, Earth will end up in a wider, safer orbit. But this might be offset by tidal effects from the sun, which are more or less comparable to the tides of the moon and which would draw our planet inward, so it would get swallowed by the sun. “We don’t know which effect will be strongest,” Villaver says.
The outcome is even harder to predict because the planets will influence the sun’s evolution during this epoch. The swallowing of Venus and the tidal interactions with Earth will dump energy into the sun’s outer layers, Villaver says. That surge could cause the sun to blow even more material into space, adding to its colorful, expanding shell of gas, which astronomers call a planetary nebula. READ FULL ARTICLE