How to Name a Protoplanet
Pallas has long been classified as an asteroid, but all of a sudden in the news media, everyone is calling it a protoplanet. How did it get promoted?
The picture being painted of asteroid 2 Pallas is that of a planetary building block that failed in its attempt to grow into another real planet. Space.com called it a “planet wannabee.” BBC News called it a “Peter Pan rock” that wouldn’t grow up. And PhysOrg announced confidently, “Study of first high-resolution images of Pallas confirms asteroid is actually a protoplanet.” That was the occasion; Hubble Space Telescope pictures of Pallas have been organized into a 3-D representation that shows the object is almost spherical. Spectral data show hydrated minerals that might indicate the presence of water ice in its past.
On a related topic, New Scientist reported that studies of another asteroid, 24 Themis, reveal the possibility of water ice – a surprise, because the ice should be evaporating at rate of a meter a year. Looking for a way to explain that, scientists think it may be leftover ice from a parent body that broke up. The article turned that bad news into good news: a collision suggests that Earth might have received its ocean water from a stray ice-endowed asteroid or comet.
The BBC article explained the thinking behind the “Peter Pan” designation for Pallas. “Theory holds that planets grow from aggregations of the dust and rock found circling new-born stars. Collisions between clumps of material produce progressively bigger objects.”
Question. Why must our minds be forced into the bottom-up picture when interpreting images of space objects? While it is true that objects of a certain mass can attract other objects and continue to grow, it is not true, despite the BBC claim, that dust and rock will aggregate into protoplanets. And collisions are more likely to disrupt and fragment bodies than make them grow (think, for example of the recent discovery of the Phoebe Ring around Saturn: 10/07/2009, and what New Scientist admitted about Themis). Why is it that the news media force these thought patterns on their readers with suggestive headlines and one-sided presentations? Did they interview Pallas and ask it, “Tell us, why did you decide to stay an adolescent, and not grow up into an adult planet?”
Let’s think out of the box. Think top-down. There was a set of original planets, moons and bodies operating as a well-crafted system. Since then, they have been perturbing each other, with collisions forming numerous craters. Some collisions were violent enough to disrupt bodies into asteroids. Others have been colliding and eroding to form planetary rings. The top-down view has an advantage: it fits one of the best-known laws of science: the second law of thermodynamics.
With this view, we can change the terminology in the news reports. Pallas is no longer to be seen as a planet wannabee. It’s a casualty of the battlefield. It isn’t a building block, but wreckage. It’s not a protoplanet; it’s a post-planet. It isn’t Peter Pan; it’s the Born Loser.