Wednesday, December 01, 2010

AHA! or, It's been awhile.

It's been a little while since we've talked about an important subject:

Now that Pluto may have regained its status as the largest object in the outer solar system, should astronomers consider giving it back another former title — that of full-fledged planet?

Pluto was demoted to a newly created category, "dwarf planet," in 2006, partly because of the discovery a year earlier of Eris, another icy body from Pluto's neighborhood. Eris was thought to be bigger than Pluto until Nov. 6, when astronomers got a chance to recalculate Eris' size.

Now it appears that Pluto reigns — though only by the slimmest of margins (the numbers are so close as to be nearly indistinguishable, when uncertainties are taken into account).

This came up in the news last week but I didn't get a chance to blog about it because I was busy making Thanksgiving preparations (yeah, can we just take a moment to remember how much I love Thanksgiving? *contented sigh*).

But the time has come, my friends, for me to address this issue. And what I say is:


I'm glad that some experts are on board with this:

"If you take the IAU's definition strictly, no object in the solar system is a planet," said Alan Stern, a planetary scientist at the Southwest Research Institute in Boulder, Colo. "No object in the solar system has entirely cleared its zone."

The definition also sets different standards for planethood at different distances from the sun, according to Stern, who is principal investigator of NASA's New Horizons mission, which is sending a spacecraft to Pluto.

The farther away a planet is from the sun, the bigger it needs to be in order to clear its zone. If Earth circled the sun in Uranus' orbit, it wouldn't be able to clean out its neighborhood and would thus not qualify as a planet, Stern said.

"It's literally laughable," he told

In Stern's view, a planet is anything that meets the IAU definition's first two criteria — the bits about orbiting the sun and having enough mass to be roughly spherical, without the "clearing your neighborhood" requirement.

So Pluto should be a planet, as should Eris and the dwarf planet Ceres (the largest body in the asteroid belt between Mars and Jupiter), as well as many other objects.

You all know my opinion on this. Let's give some love to Pluto.

Seriously, IAU, what's with the discrimination here?

1 comment:

Lost in Translation said...

I thought the whole practice of demoting Pluto was LAME SAUCE. Give us back our Pluto!