In about 5 billion years, the Sun will swell into a red giant (enveloping the inner planets), then it will become a white dwarf. (there won't be a supernova or black hole because the sun isn't large enough ... I gave a few more details on that here.
According to this site, the moon is moving away from the earth, not towards it, so I guess the Sun will die first.
The sun will envelop all the inner planets? I didn't realize that, i just knew that it would envelop Mercury.
The article I read about the moon (I don't know where it is now) said that although the moon is currently moving away from Earth one day the Earths gravity will bring it back in, closer to our planet and one day it would crash on Earth.
quote:Originally posted by Matiqua: The sun will envelop all the inner planets? I didn't realize that, i just knew that it would envelop Mercury.
The article I read about the moon (I don't know where it is now) said that although the moon is currently moving away from Earth one day the Earths gravity will bring it back in, closer to our planet and one day it would crash on Earth.
Thanks for your quick response!
Earth is included amongst the inner planets, and will be swallowed up by the expanding sun in about 5 billion years. Most life on earth will have disappeared long before then due to the intense heat. Some scientists believe it may be possible some day to change earth's orbit to one similar to Jupiter's, in order to avoid this fiery fate. The moon is indeed receding from earth at a snail's clip due to tidal friction forces which cause the earth to slow down it's rotation. This slowdown is compensated, in order to conserve angular momentum, by an increase in the orbital speed of the moon around the earth, causing the recession, which ultimately will cease in a few billion years, with the moon about 350,000 miles above earth, (on average, in an elliptical orbit) compared to it's present 200,000+ mile orbital height. When that happens, the moon will likely stay in a very stable orbit, neither receding nor dropping to earth, in a geostationary orbit where it will stay in the same spot above earth like one of those communication satellites that do not move relative to us. But it appears that the sun will gobble the moon up to, still within range of the sun's expanding radius. Goodnight, Moon.
Posts: 625 | Location: Boston | Registered: 06-13-02
We can't lose a minute! We have to get started now!
If we build a series of huge jets around the equator, and fire them sequentially sunwards as the earth rotates, we may be able to gradually enlarge earth's orbit, and dock it among the outer planets. This would take about 5 billion years.
I hear NASA's been looking for projects since the end of the Cold War. The have found only one external enemy so far: rogue asteroids. They need funds so they can prepare to blast them away from their courses as the asteroids approach earth.
Hope they don't try and recycle the Pioneer for the purpose!
