Wednesday, March 12, 2008

Earth Set to Plunge Into Sun in 7.59 Bil. Years

The Earth's fate is tied to the middle-aged star we're circling called the Sun. So what happens when the Sun moves into retirement? Basically, it will expand and suck the Earth to a fiery death, according to a report at the NY Times.

Here's how it works. As the sun gets older, it's slowly getting bigger, brighter. Since the Earth was born 4.5 billion years ago, the sun has gotten 40 percent brighter. In another billion years, it will be 10 percent brighter. At that point, the oceans are going to start boiling off and Earth's going to be a pretty miserable place for anyone stuck here.

Another 4.5 billion years after the oceans are gone, the sun will have burned through it's hydrogen core and start burning through reserves in the outer layers. That's when things get pretty interesting. As it burns through the outer layers, the sun will start to lose mass (get lighter) while simultaneously getting bigger. This process will transform our sun into a "red giant." How giant? About 256 times as big as it is now.

As the sun grows, it will swallow the planets Mercury and Venus, leaving Earth as the inner most planet in the solar system. But eventually, the close Earth-Sun interaction will cause the planet to slow to a point where it can no longer sustain its orbit. That's when the death spiral begins.

In The Times' piece, they also get into ways the Earth can be saved. For example, by harnessing the gravity of passing asteroids or comets to pull the Earth away from a growing Sun.

But after a billion years, Pound360 fully expect humans will have figured out a way to travel the stars. So we ought to just start over on a new planet elsewhere. If we haven't developed the technology to do this because of war, greed and every other short-sighted pursuit that's slowed space exploration, then human beings will deserve what they get.

Another thing this article got us to thinking about is this. Pound360 recalls reading a theory that sends the Earth in a different direction as the Sun goes red giant. As the sun expands and its mass reduces, its gravitational pull will also weaken. Given that, there's a chance the Sun could lose its grip on Earth, and our planet could spiral off into deep space.

What if that's happened to other planets in the galaxy? What if that's happened to other planets that had once been inhabited by thriving civilizations? If so, Pound360 wonders if future space explorers will study the frozen remains of ancient civilizations on planets wandering interstellar space. A fascinating thought.

(Photo Courtesy NASA)

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I started pound360 to channel my obsession with vitamins, running and the five senses. Eventually, I got bored focusing on all that stuff, so I came back from a one month hiatus in May of 2007 (one year after launching Pound360) and broadened my mumblings here to include all science.