Today is the first day of summer, also known as the summer solstice. It's the longest day of the year (and the shortest night). The actual moment of the solstice will occur at about 7:09 p.m. this evening, while the sun sits directly above the Pacific Ocean to the west of Hawaii. As you may remember from your grade school science lessons, the seasons and the changing lengths of the day and night throughout the year are a result of the Earth's axial tilt. Try to visualize the Earth's orbit around the sun as an elliptical path on an imaginary plane in space. As the Earth rests in that plane, …

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 …