Vesta was the Roman goddess of hearth and home, but there's nothing warm or cozy about her celestial namesake. That Vesta is a barren, airless "protoplanet" that circles the Sun between the orbits of Mars and Jupiter amid the primordial space debris of our solar system's main asteroid belt, where it is regularly pelted by its much tinier neighbors―and, as scientists have learned, occasionally clobbered by not-so-tiny ones.
Vesta is in the news this week because of the initial published findings from NASA's Dawn space probe, which arrived at Vesta last July as part of its mission to collect information about the earliest days of the solar system, when the planets formed.
Vesta is about 330 miles wide, which makes it the second largest object in the asteroid belt. For a sense of scale, see the accompanying graphic that shows how Montgomery County (in green) would look if its borders were marked out on Vesta's surface.
Before the Dawn probe arrived at Vesta, scientists already believed that Vesta was part of a group of bodies, known as protoplanets, that had combined through a process called planetary accretion to form Mercury, Venus, Earth and Mars: the solar system's inner, "rocky" planets. According to an article published Thursday in the journal Science, the first batch of data collected by Dawn suggests that view is correct.
What surprised scientists was how recently Vesta had been transformed by its interaction with other bodies. As recently as a billion years ago―not long, given the estimated 14 billion year age of the universe―smaller asteroids smashed into Vesta, dislodging enough material to fill the Grand Canyon 400 times. Much of that debris has fallen to Earth's surface in the form of meteorites.
How to see Vesta
Only keen-eyed stargazers will be able to spot Vesta without binoculars or a telescope, and then only when the moon isn't overpowering the night sky with its own light. Vesta typically hovers around magnitude 7.0, near the limits of the unaided eye's perception.
Right now, Vesta is lost in the pre-dawn glow of the Sun, but you'll be able to see it in the middle of the evening late this year, when it will be high in the eastern sky between the constellation Orion and the brightly shining planet Jupiter (see the accompanying graphic). Shining at a relatively bright magnitude 6.35, it should be fairly easy to find with binoculars throughout the month of December.