Sacramento Valley Astronomical Society

by Liam McDaid

January 2010 had the largest gathering of astronomers ever. The American Astronomical Society had its 215th winter session in Washington DC. I saw many old comrades of my graduate student days along with local heroes like Ken Crawford. I haven’t been to a AAS meeting in twenty years and I felt I was due. Many of us were expecting major new announcements about discoveries in astronomy. Kepler has been flying for six months and some of its data was reduced. Sadly, much of the data remains to be analyzed at this time by its overworked team.

Still, some planet discoveries were confirmed and announced. Several of them are yellow hot, and one of them has the density of styrofoam… that’s a record. I can only imagine such a planet as a disintegrating diffuse gas giant breaking up from the heat and tidal forces so close to its star. No planets within the habitable zone of their star were announced. Remember that the habitable zone (or habzone) of a star is the area around the star where liquid water can exist on the surface of a planet or moon. Note that this isn’t guaranteed, the Moon is well within the habzone of the Sun, and yet no liquid water exists there. For a planet that orbits within the habzone of its star, many odd yet awesome scenarios can exist for habitable worlds. Imagine an Earth sized world orbiting a world like Saturn. Possible? Yes. If the giant moon were well outside the rings it would be relatively safe and perhaps even insulated from major asteroid impacts. Imagine a warm Titan, with a transparent atmosphere. Chesley Bonestell lives again!

A styrofoam planet is still a little freaky. I’m waiting for the opposite extreme – a planet with the density of iron or silver. So far, such planets only exist in the realm of science fiction yet they are possible. Kepler will return information on over 100,000 stars during its run. How many of them have Earth-sized planets? How many of them have planets at all? These are vital questions that we must have the answers to before we can gain any idea about how many places may have life. Or intelligence. Or technology.

We are near a new spring. As it continues, we have three planets to view: Mars, Venus and (later) Saturn. Think of the diversity of just these three then compare that to the almost unimaginable differences between the millions of planets we have yet to find. If they’re there.

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