You know all those New Year resolutions that you have already broken? I fully intended to post this at least a week ago. Ah well, better late than never…
This post is intended to introduce people to the habit of skywatching, and once the habit is ingrained, to be sure that you will never walk outside, day or night, without at least a glance over your head. Not a bad habit to gain. Each month throughout the year (there go those resolutions again!) I intend to post a similar update for your information, and repost the background information as well. Since I am so late in the month of January, I am posting information here for February, too. I haven’t assumed any optical aid beyond a good pair of binoculars. There is plenty to see even without them.
WHAT IS INCLUDED IN EACH MONTH’S INFORMATION
Moon Phases: Full moon nights are good mostly for reading—outside by the light of the moon, or inside with a good reading lamp. They aren’t much good for sky gazing since the brightness of the moon pretty much overwhelms everything else in the sky. Nights with a new moon are dark, and that allows you to see dimmer objects that might otherwise escape your notice. Between the new and full phases, the moon waxes as more and more of its visible surface is illuminated, and it rises ever later. When it is full, it rises at sunset and sets at sunrise, visible all night long. Between the full and the new phases, it wanes, and if you confine your sky gazing to the early evening before midnight, it may not rise until well after you are done.
But the moon itself is a fascinating object, the closest and most easily observed extraterrestrial object. It especially comes into sharper view with binoculars. Look at the moon when it is less than half illuminated, and look along the line separating the illuminated surface from the dark. There the Sun is low in the lunar sky and casts long shadows that throw the deep craters and the tall mountains into higher relief. See if you can spot a bright central peak poking into the sunshine from the dark floor of a deep crater. The best online lunar map I have found is here.
Planets: I’ve confined myself to the five planets that are visible to the naked eye: Mercury, Venus, Mars, Jupiter, and Saturn. For views of Earth, look down.
Meteor Showers: I haven’t tried to include every single one of these, only the ones that might be worth your while to stay up for. The moon phase greatly affects how many meteors you will see; the ideal situation is when a shower occurs during a new moon. The radiant is the point from which the meteors appear to originate; the showers are named for the constellation in which the radiant appears. This is an optical illusion in the same way that railroad tracks appear to meet in the distance; the meteors actually follow parallel paths as illustrated below:
Deep Sky: There are only a few objects beyond the solar system that are visible to the naked eye (other than stars, of course). Even there you need a pretty dark sky. Binoculars will help, and I’ve included some of the more easily spotted objects.
HOW TO JUDGE DISTANCES IN THE SKY
It isn’t particularly useful to describe distances between two objects in the sky in miles or light years. Two objects that appear to be the same distance apart as we view them could be 2 light years from each other or 2 million. Angular distance (in degrees, where 360° is a full circle around the sky that brings you back to your starting point) is how we do this. Here is a handy guide to help you judge those angular distances.
Moon Phases: New on January 1st and January 30th ; full on January 16th
Planets: Jupiter reached opposition on January 5th and is visible virtually all night long for the entire month. Saturn rises after midnight at the first of the month, and by the end of the month, it rises a little before 2 am. Just before sunrise, it is the bright yellowish “star” low in the south. Mars rises at midnight at the first of the month, and earlier each night as the month proceeds. Mercury is normally quite difficult to see since it never ventures very far from the Sun. But on January 31st, you may be able to glimpse it just after sunset, almost directly above the point where the Sun has disappeared. Binoculars will help, but be sure you let the Sun set completely before you aim them anywhere near that part of the sky. Mercury should appear about 16 degrees above the horizon at this point.
Meteor Showers: The Quadrantids reached their peak on January 3rd. Sorry.
Deep Sky: January, and the winter sky in general, is a wonderful time to see some of the Northern Hemisphere’s most glorious sights. Here is a guide to the sky as it appears at 10 pm (local time on the East Coast of the US) at mid-month, looking south:
The easily recognizable constellation of Orion dominates the sky, with red giant star Betelgeuse at the upper left, and blue-white Rigel at the lower right. On that diagonal between them lie the three-in-a-row stars of Orion’s belt, and below that is M42, the Great Orion Nebula, a glowing cloud of hydrogen gas lit up by hot young stars embedded in it. If you are blessed with both dark skies and good night vision, you can see M42 as a non-stellar object (extended, not a point of light) even with your naked eye. Betelgeuse, Sirius (brightest star in the sky) and Procyon (its name is obscured in the image by the Canis Minor constellation name) make up the winter triangle: three bright stars easy to pick out. Aldebaran in Taurus is about halfway between Betelgeuse and M45, the Pleiades or Seven Sisters, a lovely little open cluster of stars sometimes described as a “micro-dipper”. On the other side of the image is M44, the Beehive Cluster, best (but easily) spotted with binoculars. The curved line at the top of the image is the ecliptic, the projected plane of the solar system, along or near which will lie the moon, Sun and planets. Jupiter is the bright “star” halfway between Betelgeuse and Castor (just out of view at the top) and Pollux, the twin stars of Gemini. The red vertical line is the meridian, an imaginary line that divides the sky into an eastern and a western half.
And here is the view at the same time, looking north:
The North Star Polaris is almost (but not exactly) straight north. During the course of a single night (or over the course of a year if viewed at the same time of night), the stars appear to rotate around it counter-clockwise. The asterism of the Big Dipper is only part of the constellation Ursa Major, and the “pointer stars” of Dubhe and Merak are a good way to find Polaris. Polaris is not the brightest star in the sky by any means; its special status lies in its apparent lack of motion as we view it.
On the other side of Polaris from Ursa Major is the constellation of Cassiopeia, which looks alternately like the letter M, the letter W, the numeral 3, or the Greek letter Σ depending on when you are looking. Trivia concerning the star in Cassiopeia here labeled as “Navi”: this is an alternate name for the star more formally known as Gamma Cassiopeiae. From Wikipedia:
Gamma Cassiopeiae (γ Cas, γ Cassiopeiae) is the Bayer designation for a star in the northern circumpolar constellation of Cassiopeia. Although it is a fairly bright star with an apparent visual magnitude of 2.47, it has no traditional Arabic or Latin name… It is located at the center of the distinctive “W” shape that forms the constellation’s asterism. American astronaut Virgil Ivan “Gus” Grissom nicknamed the star Navi after his own middle name spelled backwards. The star was used as an easily identifiable navigational reference point during space missions.
M31 is the Andromeda Galaxy, the most distant object visible to the naked eye in a dark sky. It is 2.5 million light years away!
Moon Phases: Full on February 14th. No new moon occurs during the calendar month.
Planets: Jupiter continues to be visible virtually all night, but by the end of the month it sets a little before 4 am. Saturn rises a little before 2 am at the first of the month, and around midnight by the end. You can spot it just before sunrise as the bright yellowish “star” low in the south. Mars rises around 11:30 pm at the first of the month, and at about 10 pm at the month’s end. Venus is just beginning to be visible as the bright “morning star” in the east just before sunrise, getting a little higher in the sky every day. Mercury has pretty much disappeared back into the Sun’s glare.
Meteor Showers: No good showers for Northern Hemisphere observers.
Deep Sky: The sky as it appears at 10 pm (local time on the East Coast of the US) at mid-month, looking south:
Not too much different from January; you’ll notice that the stars are shifted to the west relative to January, however. Stars rise a little earlier every night as the year progresses.
And here is the view at the same time, looking north:
M31 (the Andromeda Galaxy) is lower in the sky at 10 pm as it moves counter-clockwise around Polaris, beginning to disappear from view until later in the year.