When Giuseppe Piazzi discovered the first asteroid, 1 Ceres, on January 1, 1801, it was magnitude 8.0. This year you can see it nearly three times that bright, at magnitude 6.9, from mid-February through the first week of March. In fact, this is as close and bright as Ceres will become in our lifetimes.
Ceres reaches opposition on February 25th. Using the best available orbital elements and perturbation corrections, S&T’s Roger Sinnott finds that “on February 25th at 23.6 hours UT, Ceres will pass closer to Earth [1.583198 a.u.] than it has been since 1857. Ceres won’t be this close again until 4164!”This happens because the asteroid is at perihelion, its closest to the Sun in orbit, just two weeks earlier. Winter oppositions of Ceres (winter in the Northern Hemisphere) are when it gets especially close and bright.
You can spot it with binoculars in Leo using the chart at right. (Click here for a full-page, printable, black-and-white chart in PDF format.) A typical binocular’s field of view is about 6° across; compare this with the ticks 10° apart on the chart's right edge.
Ceres is magnitude 7.9 on January 1st, 7.2 on February 1st, 6.9 on March 1st, 7.4 on April 1st, and 8.0 on May 1st. The chart shows stars to magnitude 8.0.
With a diameter of 590 miles (950 km), Ceres is by far the largest asteroid and has enough gravity to pull itself into a reasonably round shape, making it the smallest known “dwarf planet” under the new, 2006 classification of the solar system’s minor bodies. It’s estimated to contain a third of the asteroid belt’s mass. NASA’s Dawn spacecraft is on its way to take up orbit around Ceres in 2015, after dallying at Vesta starting in 2011.