Friday, August 10, 2007

Another trip around the sun

This week, my grandmother, my mom and my dad each complete another orbit around the sun (85, 59, and 60, respectively). The earth, which has completed nearly 4.5 billion such trips, just keeps on trucking and is already starting another lap around the sun.

As we look into space and discover new solar systems, we are starting to appreciate the one we have. In many solar systems, a Jupiter-sized planet careens through the zones around the star capable of harboring life. Any planets that once circled in those zones have long-since been tossed into deep space. In other solar systems with faint suns, the planets close enough to be comfortably warm also become tidally locked, meaning the same part of the planet always faces the star. The lit sides of these planets will become unbearably hot, while the nighttime sides will be freezing cold.

There are almost certainly nice, habitable planets circling their suns just as the Earth is circling ours. Maybe, on one of these, some alien humanoid is also celebrating its grandmother's 85th birthday. I'd like to meet them someday (unless they would be holding a ray gun at the time, but that's just common sense).

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