If you look up the details of W Ursae Majoris, you’ll find that its two stars are about a million miles apart. The way astronomers figure that distance, though, is from the centers of the two stars. When you measure the distance between their surfaces, the stars are a whole lot closer. In fact, […]

The most massive stars are seldom alone. Most of them have one or more companions – stars that are bound to each other by their mutual gravitational pull. Such stars were born together, from the same giant cloud of dust and gas. Dense clumps in the cloud collapsed and split apart, giving birth to […]

The Sun is an unusual star in several ways. It’s the only star known to support life. It’s in the top 10 percent of the most-massive stars in the galaxy. And it’s in the minority in another way: it moves through the galaxy alone. Like all stars, the Sun probably was born in a cluster – a […]

Orion is packed with stars that are much bigger, brighter, and heavier than the Sun. But only one of them is likely to draw hisses from Harry Potter fans: Bellatrix. Its name comes from Latin, and means “female warrior.” The name was applied to one of Harry Potter’s nastiest foes – […]

The full Moon has an especially close companion tonight: Spica, the brightest star of Virgo. From the eastern half of the country, they’ll appear to almost touch each other as night falls. They’ll be a bit farther apart for those in the west, but still close. A dozen American astronauts walked […]