What Pants Need a Kuiper Belt?

Once when I worked at Martin Marietta, I decided to count how many acronyms I knew. I started making a list, but quit after about 300. It was getting ridiculous.

I've probably forgotten most of them by now, but don't worry -- I am continually acquiring new ones. My latest is "TNO" -- "Trans-Neptunian Object." When I heard the term, I figured it was probably synonymous with "KBO" -- "Kuiper Belt Object". But no, KBOs are merely a small subset of TNOs. There's a whole lot of crud floating around out there.

[Side note: I thought about using a picture of Mickey Mouse's dog, or perhaps the most famous student of Socrates...but figured that the big guy pictured above would still make you think of our former 9th planet. Plus, the implication of impending fisticuffery accurately reflects the flavor of the public debate over the topic. I'm not sure it's a spinach-worthy dispute, but some folks seems to get pretty passionate about it.]

Actually, I thought New Horizons PI Alan Stern probably has the correct answer. Basically, he said if it's spherical and orbits the sun, it's a planet. Under that definition, there are hundreds (if not thousands) of planets in our solar system -- so the debate about whether there's 8 or 9 is anachronistic. The real question is how many of the zillion TNO planets should we force schoolkids to memorize?



Pluto, for sure. And Eris, too, I would think.

Until last week's lecture, I didn't know that they had found 5 moons around Pluto (and wouldn't be surprised to find more), nor that the moon Charon was pronounced "Sharon" instead of "Chaw-ron." There will certainly be other new facts to learn once the data from New Horizons is analyzed.

The bad news is that New Horizons is moving at about 1000 miles per second, so it's entire fly-by of Pluto will last mere hours. Then it's off into deeper space. If they grab good data and the spacecraft remains fully functional, they hope to receive additional funding to fly to another KBO that's only a few years beyond Pluto.

The good news is that they have an excellent instrument suite, and have planned maneuvers to capture as much science as possible in the short time they whiz by Pluto. They're going to take pictures and chemical readings from all the moons, too...so we could learn a whole bunch of new stuff that could help the scientists understand how the solar system was formed and whether there can be life on an icy planet. I am really excited to see what we learn.

We're less than a month away from closest approach. You can follow the New Horizons mission updates at http://www.nasa.gov/mission_pages/newhorizons/main/index.html. And for fun, you can also visit http://solarsystem.nasa.gov/plutotime/ to learn when the light in your neighborhood is equal to the light you'd experience if you were standing on Pluto. For Denver on the day I wrote this, it would be after sunset, at 8:35pm. You'd probably need a flashlight if you wanted to have a good tourist experience out there.

Anyway, mark your calendar for July 14th, when New Horizons officially reaches Pluto. This is a major science event, and it deserves our attention. In the meantime, I'll leave you with a short science quiz in the panel below (click to embiggen). Enjoy it, and have a great day!