Stars

How can WR 20a, a binary star in Carina, move so fast?

In a News Note (S&T: November 2004, page 16) you described WR 20a, a binary star in Carina with components of 83 and 82 solar masses and an orbital period of 3.686 days. How can two huge balls of gas move so fast? Grab any introductory astronomy textbook and turn to the chapter on...

This Week's Sky at a Glance

Sky at a Glance, May 9 – 17

Friday, May 9 The waxing gibbous Moon in the evening sky forms a curving line with Mars to its left, and Spica to the lower left of Mars. Saturday, May 10 Bright Mars shines left of the Moon. Although they look rather close together, Mars is 260 times farther away — and twice as...

This Week's Sky at a Glance

This Week’s Sky at a Glance, June 13 – 21

Friday, June 13 Vega is the brightest star shining in the east after dusk. It's currently the top star of the big Summer Triangle. The brightest star to Vega's lower left is Deneb. Look farther to Vega's lower right for Altair. The Summer Triangle will climb higher in early evening all through the summer,...