Saturday, 6 August 2011

Asteroid Vesta at opposition on August 5, 2011



The asteroid Vesta is at opposition – opposite the sun – in Earth’s sky today. At opposition, the Earth passes in between Vesta and the sun, and it’s at or near opposition that Vesta comes closest to Earth for the year. Even so, this world still lies over 114 million miles away.

Vesta ranks as the 2nd most massive object in the asteroid belt, after the dwarf planet Ceres. The asteroid belt consists of thousands of little potato-shaped worlds that circle the sun in between the orbits of the planets Mars and Jupiter. Vesta, though, is more ball-shaped than most asteroids. Its diameter spans about 300 miles, and you’d have to have 7 Vestas lined up side by side to equal the diameter of our moon.

Dawn spacecraft

Trajectory of Dawn spacecraft from Sep 2007 until Jul 2015

This year, the Dawn spacecraft is scheduled to arrive at Vesta in July 2011 and to study this mysterious world until July 2012. Thereafter, Dawn will leave for Ceres, to arrive at the only dwarf planet to inhabit the asteroid belt in February 2015.

Graphic on right courtesy of Wikipedia Commons. Click here for a larger version.

Believe it or not, you don’t have to be aboard the dawn spacecraft to view Vesta. You can see it for yourself in front of the constellation Capricornus tonight. If you know right where to look, you can easily spot Vesta with binoculars, though it’ll only appear as a faint speck of light. In a dark country sky, sharp-eyed people can actually see Vesta with the unaided eye. Click here for a detailed sky chart.

The best time to look for Vesta is around midnight (1 a.m. daylight saving time), when it’s highest in the sky. This opposition gives you an opportunity to catch Vesta, as the sky’s brightest asteroid shines at its brilliant best in Earth’s nighttime sky.