Spinning Vesta

A new study of Vesta, the second largest asteroid in the Solar System, has found Vesta has a slightly larger axial tilt than previously thought. Using images snapped by the Hubble Space Telescope, the study also determined Vesta spins once on its axis every 5.3 hours.

The new information is timely because NASA's Dawn spacecraft will encounter Vesta next year. Knowing the tilt will allow scientists to better plan Dawn's observations of the surface as they factor in the angles at which sunlight will strike certain areas at certain times.

After its time at Vesta, Dawn is scheduled to reach Ceres in 2015. While Vesta is roughly 330 miles along its major axis, Ceres, the largest asteroid, has a diameter of something around 800 miles, similar to the distance all the way across Texas. Ceres is the only asteroid massive enough to have the gravity to pull itself into a sphere, thus the only one with a meaningful diameter.