Eight is Enough

A fun pop quiz for the first day back to school…

How many planets are there?

If you just thought “Nine”, you are wrong.

As of Thursday, there are now only eight planets, as Pluto has officially been demoted to “Dwarf Planet” status. It is decidedly too small, and in a too-populated area of space to be considered an official planet. The new description of what constitutes a planet is rather vague and confusing, I must say.

Granted, Pluto has been considered a planet for 70 some years now, but at its discovery its actually size was not accurately known, and some have argued that had it been at the time, Pluto would never have achieved planetary status.

This is not the first time a planet has been demoted either. At the time of their discoveries, the asteroids Ceres, Pallas, Juno, and Vesta were all called planets. Not until later was it discovered that these were only the largest of the thousands of objects in the asteroid belt. Pluto’s fate is very similar, as it has been discovered to be the largest of the items, as well as one of the nearest, in the Kuiper belt.

A second proposal by the International Astronomical Union would have brought the total number of planets to 12. This proposal not only kept Pluto, but added Ceres, the largest asteroid, as well as Pluto’s moon Charon (because Charon does not actually orbit Pluto, but instead the both orbit a point between them, they are technically a “Binary Planet System”, not a planet and moon), and the body “2003 UB313”, the “10th Planet” discovered in 2003 even further out than Pluto. That proposal, however, was voted down, and the new system later voted in.

How long this will stand is unknown. Only 400 some of the 10,000 astronomers who could have voted did, so it is not yet set is stone forever. That there may be a new proposal to grandfather Pluto as a planet and make all future discoveries dwarfs is possible, and even if the decision stands, future clarification is certain.

For more info, please see Wikipedia or Space.com.

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