Comments on: The Metro Atlanta Solar System

By: Laurel Kornfeld

Laurel Kornfeld — Tue, 29 Sep 2009 16:29:41 +0000

Pluto is not just the “nearest object in the Kuiper Belt,” and its demotion resulted from one interpretation of more extensive knowledge of the outer solar system. The overwhelming majority of Kuiper Belt Objects are not large enough to be in hydrostatic equilibrium, that is, rounded by their own gravity. This is how Pluto, Haumea, Makemake, and Eris differ from the majority of Kuiper Belt Objects. Objects in hydrostatic equilibrium are often geologically differentiated into core, mantle, and crust, just like Earth, and have weather and geological processes that smaller, non-spherical bodies do not have. The new knowledge about the outer solar system is that these objects exist; it does not dictate that Pluto and these objects aren’t planets. That is an interpretaition favored by dynamicists, a class of astronomers who study how objects interact with and effect one another. A different interpretation, the one Stern and many planetary scientists support, is that the new knowledge tells us we have a third class of planets in addition to terrestrials and gas giants–the dwarf planets.

A big problem is that the IAU definition specifically states that dwarf planets are NOT planets. Not only does this make no linguistic sense; it also goes against the use of the term “dwarf” in astronomy, where dwarf stars are still stars and dwarf galaxies are still galaxies. If this one provision were amended to establish dwarf planets as a subclass of planets, much of the controversy would dissipate.

The demotion passed with only four percent of the IAU voting because the IAU has archaic policies that don’t allow any absentee voting. The vote was held on the last day of a two-week conference, when most attendees had already left. Also, the resolution was put on the floor in violation of the IAU’s own bylaws, which require resolutions first be vetted by the appropriate committees before being placed on the floor of the General Assembly for a vote. The IAU’s committee had recommended a different resolution that included Ceres, Eris, Charon, and Pluto as planets. Members who left early expected that resolution to be on the floor and had no idea that a small group would hijack the process and substitute it with a different resolution. The IAU has about 10,000 members worldwide. About 2,500 attended the start of the 2006 General Assembly. By the time of the vote, only 424 remained, and this is the number of people who took part in the vote.

By: Mark

Mark — Mon, 28 Sep 2009 22:18:46 +0000

Put Pluto at Kennesaw State University. Anybody have a school, college or state park we can put Eris in?

By: Mark

Mark — Mon, 28 Sep 2009 22:15:09 +0000

And not only should we put Pluto in, but also Eris, which is slightly larger than Pluto.

Eris’ median distance from the Sun is 67.67 astronomical units, so using the one kilometer = one AU formula, I guess you can put Eris at Lumite, Inc. at 2100 Atlanta Road in Gainesville. There are other places 67.67 kilometers from Bradley Observatory, but that’s the first notable location I’ve found.

By: Decatur Metro

Decatur Metro — Mon, 14 Sep 2009 02:07:23 +0000

Geez Chris, you could have at least given me the astronomical units. That whole process required at least 3 Google searches!

OK everyone, here are our Pluto options, based on the fact that Pluto is 39.52 astronomical units from the Sun.

Gwinnett County Airport
Collins Hill, Olde Atlanta, or Laurel Springs Golf Course
Kennesaw State University
Cobb County Airport
Marietta Country Club
Taylor Farm Park
Stout Park
Douglasville
Palmetto
Atlanta Motor Speedway
Georgia National Golf Club
Loganville

Take your time. This is probably the biggest decision you’ll make all week.

By: Chris

Chris — Mon, 14 Sep 2009 00:30:57 +0000

I know that there are lots of Pluto defenders out there. As an astronomer (who didn’t participate in the vote btw), I have to say that I agree with the decision. I saw it as creating another subclass of planets (dwarf planets), and my guess it that in the coming decades, with better telescopes, we will discover many Pluto-sized (or larger) objects in the outer reaches of our solar system-as we have already started to do.

For those you are confused by the back and forth placement of planets, you can notice in the map of the Metro Atlanta Solar System that the planets are located along their orbits. My colleague at Emory mused that it would be interesting to determine when the planets have been in these exact relative locations. Tough problem!