The Evening Sky in February 2015
Whole sky chart for Feb 2015
Bright planets appear on opposite sides of the sky at dusk. Brilliant Venus appears low in the west soon after sunset. Jupiter appears low in the northeast, shining with a steady golden light. Above and right of Venus, for most of the month, is the red planet Mars. It is much fainter than Venus but is the only other brightish star in that vicinity. Venus keeps its position in the twilight all month. Mars slips down the sky. Venus and Mars will be close together around the 21st. After that Mars disappears into the twilight. Their closeness is just a line-of-sight effect. On the 21st Venus is 213 million km from us; while Mars is 329 million km away. The crescent moon will be near the pair of planets on the 21st.
A telescope will easily show Jupiters four bright moons. Binoculars, steadily held, often show one or two of them looking like faint stars very close to the planet. Jupiter is 652 million km from us mid month, the closest it gets this year. The planet is 11 times Earth's diameter and 320 times Earth's mass. It sets in the northwest at dawn.
Sirius, 'the Dog Star', marks the head of Canis Major the big dog. A group of stars above and right of it make the dog's hindquarters and tail, upside down. Procyon, in the northeast below Sirius, marks the smaller of the two dogs that follow Orion the hunter across the sky. Sirius is eight light years* away.
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 three makes the bottom of 'The Pot'. The handle of The Pot is Orion's sword, a fainter line of stars above the bright three. At its centre is the Orion Nebula; a glowing gas cloud around 1300 light years away.
Orion's belt points down and left to the orange star Aldebaran. Continuing the line finds the Pleiades or Matariki star cluster. Aldebaran is Arabic for 'the eye of the bull'. It is on one tip of an upside-down V that makes the face of Taurus. The V-shaped group is called the Hyades cluster. It is 130 light years away. Aldebaran is not a member of the cluster but merely on the line of sight, 65 light years from us. It is 145 times brighter than the sun. The Pleiades or Matariki star cluster is also known as the Seven Sisters and Subaru. Six stars are seen by eye; dozens are visible in binoculars. The cluster is 440 light years from us. From northern New Zealand the bright star Capella is on the north skyline. It is 90,000 times brighter than the sun and 3300 light years away.
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 can be traced up the sky, fading where it is nearly overhead. It becomes very faint east, or right, of Orion. The Milky Way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one.
The Clouds of Magellan, LMC and SMC are high in the south sky, easily seen by eye on a dark moonless night. They are two small galaxies about 160 000 and 200 000 light years away.
Saturn (not shown) rises in the southeast before 2 a.m. at the beginning of the month; at midnight by the end. It has a creamy colour. To its right and fainter is the orange star Antares, marking the Scorpion's heart. Saturn is 1506 million km away mid month. It is always worth a look in a telescope.
Mercury (not shown) makes its best morning sky appearance of the year in February and March. It moves rapidly up the eastern dawn sky in the first week of February. By the 14th it is rising two hours before the sun, the only bright star in the east. It remains prominent in the morning sky through March.
*A light year (l.y.)is the distance that light travels in one year: nearly 10 million million km or 1013 km. Sunlight takes eight minutes to get here; moonlight about one second. Sunlight reaches Neptune, the outermost major planet, in four hours. It takes four years for sunlight to reach the nearest star, Alpha Centauri.
Notes by Alan Gilmore,
University of Canterbury's Mt John Observatory,
P.O. Box 56,
Lake Tekapo 7945,