The Evening Sky in March 2025
Total eclipse of the Moon on March 3-4. The full Moon starts to enter the fuzzy edge of the Earth’s shadow, the penumbra, at 9:43 pm NZDT, but won’t show obvious fading at first. At 10:50 it starts to move into the dark part of the shadow, the umbra. It is fully in the shadow just after midnight. At 12:34 the Moon is in the deepest part of the shadow. It begins to emerge from the umbra at 1:03 a.m. and is fully out by 2:18. It leaves the penumbra at 3:25. Just how dark the Moon gets depends on how much light is being bent around the Earth by the atmosphere. As no recent volcanoes have put dust into the air, the totally eclipsed Moon is likely to stay fairly bright and be a ‘blood moon’.
Jupiter is the ‘evening star’, appearing low in the north at early twilight. It sets in the northwest after 2 a.m. at the beginning of the month, and before 12:30 a.m. at the end. The Moon will be near Jupiter on the 26th. From places with a sea horizon to the west brilliant Venus might be seen setting half an hour after the Sun. Northwest of overhead is Sirius. It is the brightest true star in the sky, but fainter than Jupiter. Southwest of the zenith is Canopus, the second brightest star. Below and left of 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 orange Aldebaran. It is at one tip of an upside-down V. The V is the face of Taurus the bull with Aldebaran being one of his eyes. Further down and left is the Pleiades or Matariki star cluster.
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 are gathering together to make new stars.
Below and right of Jupiter 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 Praesepe star cluster, 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 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.
On the 10th the Moon crosses in front of Antares, the bright orange star in Scorpius. Antares will disappear around 11:30 pm NZDT and reappear an hour later. The exact times depend on your location.
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.
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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