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I have to admit, I wsn't surprised by the astronomy news this morning: Pluto has lost its status as a planet.
This has been brewing for a while. Pluto has always been an oddball - it doesn't orbit the sun in the plane of the ecliptic the way all the other planets do. It's always been far smaller than the other planets - barely larger than an asteroid. Charon, long considered it's "moon," has turned out to not actually be orbiting Pluto at all, but both bodies are orbiting each other around a common center of gravity. And a recent discovery of 2003 UB313 (nicknamed "Xena"), an even larger body out farther than Pluto in the Kuiper belt, has also jeopardized Pluto's planetary status. Keeping Pluto as a planet would require defining the larger Xena as a planet, defining Pluto-Charon as a binary planet, as well as redefining Ceres, the largest asteroid in the asteroid belt, as a planet. And we still don't know what else is out there beyond Xena.
As of today, we are now officially back to 8 planets in the solar system: Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune.
I think it's a good decision - I have been hoping for several weeks that this is where the astronomers would draw the line - but it still seems kind of sad. The Solar System seems a smaller place today.
This has been brewing for a while. Pluto has always been an oddball - it doesn't orbit the sun in the plane of the ecliptic the way all the other planets do. It's always been far smaller than the other planets - barely larger than an asteroid. Charon, long considered it's "moon," has turned out to not actually be orbiting Pluto at all, but both bodies are orbiting each other around a common center of gravity. And a recent discovery of 2003 UB313 (nicknamed "Xena"), an even larger body out farther than Pluto in the Kuiper belt, has also jeopardized Pluto's planetary status. Keeping Pluto as a planet would require defining the larger Xena as a planet, defining Pluto-Charon as a binary planet, as well as redefining Ceres, the largest asteroid in the asteroid belt, as a planet. And we still don't know what else is out there beyond Xena.
As of today, we are now officially back to 8 planets in the solar system: Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune.
I think it's a good decision - I have been hoping for several weeks that this is where the astronomers would draw the line - but it still seems kind of sad. The Solar System seems a smaller place today.