Pluto Bites the Dust

In "A Death in the Solar System" [November], we read that according to the new International Astronomical Union [IAU] definition of a planet, it must be "round but must also dominate the mass of its orbital zone. In other words, a full-fledged planet must have no competitors in its zone." But if Pluto is not a planet, then neither is Neptune, whose orbit is crossed by and has not been cleared of . . . Pluto!

Jerry J. Svoboda
Rochester, New York

Courtesy of NASA

Neil deGrasse Tyson rightly points out the fuzzy boundary between a dwarf planet and a smaller "solar system object" but ignores the bigger debate over the arbitrary boundary between a dwarf planet and a planet. What if we find something the size of Mercury out beyond Pluto? Will we call it a planet or a dwarf planet? The word planet has still not been defined—we have only the introduction of a new term without a clear distinction between the two.

Eric Oscar
Clifton, British Columbia

I would like to congratulate the IAU on their brilliant decision to strip Pluto of its status as a planet. Now it's only a matter of time before Earth loses its planet status, too—and about time! After all, Jupiter's volume is over a thousand times bigger than Earth's, its mass is over 300 times larger, and its chemical composition is almost entirely different (mostly gas, instead of rock and metal). Only an idiot would place Jupiter and Earth under the same astronomical classification.

Brett Bochner
Associate professor
Dept. of Physics and Astronomy
Hofstra University
Uniondale, New York

Enviro-Aid

Thank you for the interview with Jeffrey Sachs of the Earth Institute regarding his efforts to combat global poverty [November]. As he says, "the lassitude of the administration is shocking and shameful" concerning research on the use of carbon-management technology. This is unconscionable in the face of what's now known about our global environment. Opposition to the exploration of possible solutions to global warming is not in humankind's best interest. Funding must be made available for this research.

Kurt Stokke
Port Angeles, Washington

We're Safe!

Regarding "20 Things You Didn't Know About Lab Accidents" [November]: Scientists are absolutely certain (not "reasonably," as the article says) that so-called black holes at the Relativistic Heavy Ion Collider (RHIC) cannot escape and consume Earth. There are certain similarities between the "fireball" created at RHIC (an extremely hot bit of matter smaller than an atomic nucleus) and a type of theoretical black hole—the same mathematical methods can be applied to analyzing both. But this theoretical black hole is completely different from a black hole in the real universe: It cannot grow by gobbling up matter. Because the amount of matter created is so tiny, RHIC cannot possibly produce a true planet-swallowing black hole.

Dmitri Kharzeev
Head, Nuclear Theory Group
Physics Department
Brookhaven National Laboratory
Upton, New York

Editor's note: We were kidding.