Bright, ruddy Mars will be overhead in the middle of the constellation Gemini, approximately by Castor’s hand.
Castor is a visual double star made up of two blue-white stars, A and B, of 1.9 and 2.9 magnitudes respectively. The pair orbit each other every 400 years and are now as close as they ever get, making them somewhat of a challenge to split and requiring good seeing. In fact their spectra show that each is itself a double star. Castor A is made up of two identical 2 solar mass stars orbiting each other every 9.2 days while the stars that make up Castor B orbit even faster, every 2.9 days.
Pollux is one of few stars visible to the naked eye which features an extrasolar planet.
Castor is a visual double star made up of two blue-white stars, A and B, of 1.9 and 2.9 magnitudes respectively. The pair orbit each other every 400 years and are now as close as they ever get, making them somewhat of a challenge to split and requiring good seeing. In fact their spectra show that each is itself a double star. Castor A is made up of two identical 2 solar mass stars orbiting each other every 9.2 days while the stars that make up Castor B orbit even faster, every 2.9 days.
Pollux is one of few stars visible to the naked eye which features an extrasolar planet.
Saturn will be in the east as darkness falls, very close to the star Regulus, the heart of the Lion, Leo.
Regulus is the brightest star in the constellation Leo and one of the brightest stars in the nighttime sky. Regulus is approximately 77.5 light years from Earth.
Regulus has about 3.5 times the Sun’s mass and is a young star of only a few hundred million years. It is spinning extremely rapidly, with a rotation period of only 15.9 hours, which causes it to have a highly oblate shape. This results in so-called gravity darkening: the photosphere at Regulus' poles is considerably hotter, and five times brighter per unit surface area, than its equatorial region. If it were rotating only 16% faster, centripetal force would overcome gravity and the star would tear itself apart.
Regulus is a multiple star system composed of a hot, bright, bluish-white star with a pair of small, faint companions. The pair orbits the much-larger Regulus A with a period of over 130,000 years at a distance of some 4,200 AU. The companion pair have an orbital period of 2,000 years and are separated by about 100 AU.