It Gets More Crowded Up There Every Day

Some of the most exciting and groundbreaking astronomical discoveries of the last few years have been in the field of exoplanet research. Particularly in the wake of the Kepler mission, we are becoming increasingly aware that the sky is filled to the brim with exoplanets.

Images taken two hours apart showing 2012 VP113 moving with respect to background stars (source).

One thing that you don't hear about every day, though, is a new object being discovered in our own solar system. But that's exactly what happened just a little over a week ago, when NASA announced the discovery of a rocky sphere around 500 km across orbiting the Sun at a frigid distance of 80 AU (that'd be $1.2 \times 10^{15}$ cm)--and that's at its closest approach! When this ball of ice, creatively dubbed 2012 VP113, reaches aphelion (the farthest point in its orbit) it's seven times farther away!

2012 VP112's orbit. The scale is too large to show any orbit smaller than Saturn's (source).

Even that isn't the farthest any object gets on a Solar orbit--lonely Sedna flies even farther, as does Eris. But it's the perihelion (the closest approach) that really has folks interested, though. There are other objects which we know get farther away from the Sun than 2012 VP113 does, but no one has ever observed an object orbiting the sun that stays as far away as it does. In fact, 2012 VP113's perihelion distance is so large it never even comes inside the Kuiper Belt. Its home lies much farther out, in the still-largely-just-theorized Oort Cloud, the home of comets and other objects on hugely elliptical orbits. We know very, very little about this distant collection of icy rocks, so it's exciting to have detected an object that calls it home.

The Oort Cloud, with the Kuiper Belt inset (source).

The Oort Cloud is incredibly big, utterly dwarfing Pluto's orbit--and we don't know for 100% sure that it's even there. There may well be the "many billions of comets" out there that the image above depicts, but they would only rarely make appearances in the inner solar system and detecting such objects at distances in the hundreds--or thousands--of AU is nearly impossible. So discoveries like this one are an encouraging sign that our theories are on the right track. While studying an object like 2012 VP113 is a challenge, to say the least, even knowing that it's out there is a promising hint of discoveries that may be to come. As our equipment and techniques improve, we may well discover that we were exactly right about the Oort cloud--or that the truth is something far more bizarre and fascinating than we imagined.