Thursday, December 11, 2008

Mark Your Calendars

As a star dies, it paradoxically expands and grows more luminous - a long shout of greatness before the silence. As the star's nuclear core peters, it collapses causing great heat, rendering helium from hydrogen, and so causing enormous expansion. The expansion compels temperature reductions and a visible light shift toward red. For that reason such dying stars are known as red giants.

Our Sun is destined for this spectacular fate in about 5 billion years. The then ravenous giant is likely to swallow our little planet into oblivion (h/t DJ). But first the star will cook our Earth to unlivable temperatures. This assumes nothing destroys the Earth in the interim. By the time the Sun dies, we will have presumably long ago vacated our home, if we're not ourselves gone (after all, 99.9% of our planet's species are extinct).

That we know the future of the Sun and Earth with some certainty is pretty extraordinary. There may be a day to do something about it, but for now I take it as warning against our solipsistic inclinations.

(image credit: artist's impression of a red giant swallowing a planet, NASA, livescience.com)