The Evening Sky in March 2024
Jupiter is the ‘evening star’, appearing in the northwest at early twilight. It sets around 11 pm at the beginning of the month and 9 pm at the end. The Moon will be near Jupiter on the 14th. Northwest of overhead is Sirius. It is the brightest true star in the sky. Southwest of the zenith is Canopus, the second brightest star. Below Sirius are bluish Rigel and orange Betelgeuse, the brightest stars in Orion. Between them is a line of three stars: Orion's belt. To southern hemisphere star watchers, the line of stars makes the bottom of 'The Pot'. Orion's belt points down and left to a V-shaped pattern of stars. This makes the face of Taurus the Bull, upside down to us. The orange star Aldebaran is at one tip of the V making one eye of the bull. Continuing the line from Orion down and left finds the Pleiades or Matariki star cluster, low in the northwest. It sets after 10 pm, mid-month. The cluster is about 440 light-years* away.
Sirius is the brightest star both because it is relatively close, nine light years away, and 23 times brighter than the sun. Rigel is a bluish supergiant star, 40 000 times brighter than the sun and much hotter. It is 800 light years away. Orange Betelgeuse is a red-giant star, cooler than the sun but much bigger and 9000 times brighter. Betelgeuse is 400 light years from us.
The handle of "The Pot", or Orion's sword, has the Orion Nebula at its centre; a glowing gas cloud many light-years across and 1300 light years away. It is a place where dust and gas in space is gathering together to make new stars. Some of the stars are much bigger and hotter than the Sun. Ultra-violet light from them causes the left-over gas to glow, making the nebula.
Near the north skyline are Pollux and Castor marking the heads of Gemini the twins. Though paired in mythology, the two stars are not related at all. Castor is a hot white star like Sirius but 52 light years away. Golden Pollux is bigger and brighter but cooler than Sirius and 34 light years away. Above and right of them is the star cluster Praesepe, marking the shell of Cancer the crab. Praesepe is also called the Beehive cluster, the reason obvious when it is viewed in binoculars. It is some 500 light years from us.
Crux, the Southern Cross, is in the southeast. Below it are Beta and Alpha Centauri, often called 'The Pointers'. Alpha Centauri is the closest naked-eye star, 4.3 light years away. Beta Centauri, like most of the stars in Crux, is a blue-giant star hundreds of light years away. Canopus is also a very luminous distant star; 13 000 times brighter than the sun and 300 light years away.
The Milky Way is brightest in the southeast toward Crux. It becomes broader lower in the southeast toward Scorpius. Above Crux the Milky Way can be traced to nearly overhead where it fades. It becomes very faint in the north, right of Orion where we are looking toward the Galaxy's nearby edge. The centre of the Galaxy is in the broad part of the Milky Way below Scorpius in the southeast.
The Clouds of Magellan, LMC and SMC are high in the south sky. They are easily seen by eye on a dark moonless night, looking like misty patches. They are two small galaxies about 160 000 and 200 000 light years away. The Large Cloud is around a quarter the mass of the Milky Way.
The full Moon may look a little odd on the 25th as it grazes the outer part of Earth’s shadow, the penumbra. It will be most in the shadow around 8:13 pm NZDT. The top edge of the Moon will be darkest.
Bright planets are in the dawn sky. Venus is the brilliant ‘morning star’, rising soon after 5 a.m. at the beginning of the month and around 6:30 at the end. At the beginning of the month Mars is just above Venus, looking like a medium-bright reddish star. It moves up and away from Venus. Later in the month, Saturn appears and moves up the sky morning-to-morning. It is the same brightness as Mars. On the 22nd Saturn will be just to the right of Venus, with less than a full Moon’s width between them. Mars and Saturn move up the sky while Venus stays put. By the end of the month Mars, Saturn and Venus are roughly equally spaced on a line. The Moon will be near Venus on the 9th.
A light year (l.y.) is the distance that light travels in one year: nearly 10 million million km or 10^13 km. Sunlight takes eight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes sunlight four years to reach the nearest star, Alpha Centauri.
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