Vesta at Opposition

The asteroid Vesta reaches opposition on December 8, rising at sunset among the bright stars of the constellation Taurus. At magnitude 6.4, it will nearly reach naked-eye visibility for observers in the northern and southern hemispheres.  And it’s easy enough to find with binoculars between two bright stars in Taurus and just a hair northward of two star clusters.

Vesta orbits the Sun every 3.63 years in asteroid belt, a region between Mars and Jupiter which holds millions of small bodies which may constitute the remains of a failed planet early in history of our solar system. Vesta is the brightest of the asteroids and second largest in size only to Ceres, which itself is now classified as a dwarf planet.

The relative sizes of Vesta (left) Ceres (middle) and the Moon (right).

To find Vesta this week, look a little south of a line drawn between the bright star Aldebaran to zeta Tauri (see images below). Vesta is the brightest object between the star m Tauri and the open star clusters NGC 1807 and NGC 1817. It’s a little fainter than m Tauri but it will still be unmistakably bright in binoculars or a small scope.

Vesta in the constellation Taurus in December 2012. The asteroid lies between the stars Aldebaran and zeta Tauri (click to enlarge).

On December 8, 2012, Vesta lies between the stars Aldebaran and zeta Tauri, and more precisely between the 5th-magnitude star m Tauri and the star clusters NGC 1807 and NGC 1817 (click to enlarge).

This is an excellent part of the sky to examine with binoculars because it holds the large and rich star clusters known as the Hyades and the Pleiades.

And if you’re clouded out, or if you’re a dyed-in-the-wool armchair astronomer, take an up-close tour of Vesta through the cameras of NASA’s Dawn spacecraft which visited Vesta last year…