Astronomers Say Dying Sun Will Engulf Earth

iamlucky13 writes "A minor academic debate among astronomers is the final fate of the earth. As the sun ages and enters the red giant stage of its life, it will heat up, making the earth inhospitable. It will also expand, driven by helium fusion so that its outer layers reach past the earth's current orbit. Previously it had been believed that the sun would lose enough mass to allow earth to escape to a more distant orbit, lifeless but intact. However, new calculations, which take into account tidal forces and drag from mass shed by the sun, suggest that the earth will have sufficiently slowed in that time to be dragged down to its utter destruction in 7.6 billion years. "

Comments

This is news?

[Cobalt Jacket]

This is the way I was taught it would happen on astronomy shows from the 1980s. I don't get the big deal.

Re:This is news?

[MillionthMonkey]

They thought for a little while that the Earth might just make it, but now it's pretty clear to everybody that's not going to happen.

Re:This is news?

[beadfulthings]

Carl Sagan in his 1980 pop-astronomy series "Cosmos." He was quite poetic, talking about one "last, perfect day" for Earth as we know it as the sun begins its changes. 'Twas quite a hit in its day, that series (and book).

confusion re expanding to earth's orbit vs engulf

[Danny Rathjens]

I was looking for something to mod up but all the replies so far are about how they learned the earth would be engulfed and surprised at the debate. I think the confusion is arises because there is no debate about whether the sun will expand to the size of earth's orbit. The debate is whether the earth will have moved far enough from that current orbit to not be engulfed. Here we go, wikipedia says precisely this:

While it is likely that the expansion of the outer layers of the Sun will reach the current position of Earth's orbit, recent research suggests that mass lost from the Sun earlier in its red giant phase will cause the Earth's orbit to move further out, preventing it from being engulfed. http://en.wikipedia.org/w/index.php?title=Sun&oldid=193657154#Life_cycle

And some of the academic references are actually a decade old: http://www.astronomy.ohio-state.edu/~pogge/Lectures/vistas97.html

I wouldn't worry about it...

[AbsoluteXyro]

When speaking of planetary catastrophe the death of our Sun is but a distant worry. It has already been mentioned that in about 3 billion years the galaxy Andromeda will collide with our own Milky Way galaxy. That of course poses several dangers to Earth in itself, though none particularly likely due to the vast distances between stars within galaxies, the potential for a stellar marauder to interfere with our solar system and cause chaos for Earth does exist. More worrisome, though, is the fact that around the same time (3 billion years from now) the Earth's core will finally cool and it's magnetic field generating dynamo will shut down, causing the Earth's shielding from the solar wind to collapse and the atmosphere to be stripped away eventually leaving the planet as dry and barren as Mars. Well before that ever happens, Earth will have to deal with the solar system's bobbing and weaving in and out of the galactic plane, possibly exposing the planet to deadly cosmic rays. Even nearer to our future is the fact that a conveniently aimed gamma ray burst from an exploding star (Betelgeuse is ready to go any day now) could "sterilize" the planet. Then of course, there is the ever present threat of an Earth shattering asteroid impact, which happens every 100 million years or so on average... in which case you could consider Earth overdue for another one. So yeah... the Sun engulfing the Earth (or what's left of it) 7 billion years from now... I wouldn't sweat that one.