PLANET fever consumed the International Astronomical Union meeting in
Manchester this week. The 10 new planets reported to be orbiting distant stars
bring the total so far to about 50. Six years ago the only planets in the
Universe seemed to be the nine in our own Solar System.
Like their predecessors, the newcomers are a motley crew. Most are so massive
they must be gas giants, like Jupiter. But they do not sit in the same
comfortable orbit as Jupiter. Some are much closer to their stars, orbiting at a
fantastic pace, while others fly off in long elliptical orbits. Why are
astronomers so excited? They are being forced to rethink their theories of how
solar systems form, and challenged to explain the physics of the wild
orbits.
The next step, of course, is to find planets the size of our own. But that鈥檚
unlikely with the present technique, which depends on spotting stars that wobble
because of the gravitational pull of their giant companions. A slew of projects
in the pipeline use different detection methods, such as looking for the dimming
of stars as planets cross in front of them
(New 杏吧原创, 18 September 1999, p 32). It
may be that we find an Earth-sized planet in an orbit that
allows water to stay liquid鈥攐ne of the necessities of life as we know it.
If that happens, then we鈥檒l really see planet fever.
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