It’s Raining Planets in Pasadena

Your Breaking Orbit blogger is back from vacation, and I’ll be bringing you highlights direct from the 42nd meeting of the American Astronomical Society’s Division of Planetary Sciences in Pasadena, California.

It’s a cold, drizzly day outside the convention center, but inside it’s raining hot new finds about planets, dwarf planets, exoplanets, minor planets, and more!

To start, let’s look at some results from NASA’s Wide-Field Infrared Survey Explorer, or WISE.

Since its launch in December 2009, WISE has been circling Earth in a polar orbit, scanning the sky twice every 95 minutes in several wavelengths.

Infrared is a way of looking at the heat coming from an object and, perhaps surprisingly, the frigid conditions in Earth orbit are not cold enough for infrared probes to capture the faint signals of heat from very distant bodies.

So, like the Spitzer Space Telescope, WISE was outfitted with two cryogenic tanks to keep the craft’s heat-sensitive instruments nice and frosty.

Designed to look at far-flung galaxies, relatively cool stars, and dark nebulae, WISE has also spotted hundreds of comets, asteroids, and other small bodies orbiting in the far outer solar system.
Watch a video of how WISE takes its comet and asteroid census:

—Video courtesy NASA Jet Propulsion Laboratory California Institute of Technology

In fact, WISE has been one of the most successful comet hunters yet launched, James Bauer of the Jet Propulsion Laboratory said today at a DPS session.

The craft not only collected new data on 93 known comets, it found 19 new comets orbiting as far away as seven astronomical units (AU)—that’s just over 650 million miles (more than a billion kilometers) from Earth.

WISE also collected data on centaurs, a class of objects with unstable orbits that act somewhat like crosses between comets and asteroids.

In addition to scanning 13 known centaurs, WISE discovered 5 more ranging out to 16 AU, almost 1.5 billion miles, or 2.4 billion kilometers, from Earth.

“A lot of our objects were highly eccentric,” Bauer told the room during his talk, and there was a large range of activity levels in the newly discovered objects.

In other words, WISE found that the outer solar system comets and centaurs have orbital paths that are shaped more like wide ellipses than perfect circles, and they vary widely in terms of how much material they are shedding as they travel (which might explain why they’ve been hard to find).

Unfortunately, NASA announced today WISE’s coolant tanks are now empty, bringing its ability to see very distant infrared sources to a close.

The good news is that, even though WISE has run out of coolant, it’s been approved to stay active for a “warm phase” of its mission, so it’ll have more time to boost what we know about comets, asteroids, centaurs, and other objects left over from the formation of the solar system.
Comet C/2007 Q3 as seen by WISE

—Image courtesy NASA/JPL-Caltech/UCLA

Human Journey