Nightskies_jan_26

Jeff Green | Jan 26, 2006

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TheNightSkies ofFebruary, 2006:The great winter circle of stars and two brilliant morning planets

by Leo Enright

The month of February continues to give us the spectacular winter constellations high in the southern sky during the evening hours, along with a few of the distinct, but less spectacular “spring constellations” which are now beginning to make their way into view, to be noticed by those who linger a bit longer in order to do some late evening observations. For those who rise in the early morning, there are even a few of the “summer constellations” to be seen in the eastern sky in the hour before sunrise.

With the ending of evening twilight on any clear evening of February, we are sure to recognize the distinctive stars that outline the shape of Orion, the Hunter, marching westward across the southern part of the sky. He and his attendants provide us with a great array of brilliant stars, the likes of which are not seen in any other season of the year. Seven bright stars mark the shoulders, knees, and belt of this giant figure as it was pictured in the minds of our ancient ancestors. In addition, six other very bright stars surround him, almost filling the southern half of the sky. First, to the eastern half of the great circle: looking downward and to the left in a line from his three ‘belt-stars’, we easily see Sirius, brightest star in the whole sky, marking the eye of Orion’s big dog Canis Major, and slightly up from it and to the left is Procyon, eighth brightest star in the sky, the star marking the head of his smaller canine friend, Canis Minor. Continuing upward in the huge half-circle left of Orion, we see Castor and Pollux, a pair of stars of similar, thought not perfectly equal, brightness, that are seen as the heads of the Heavenly Twins whom our ancestors saw as standing side by side. Now to the western half of the great circle, the part of it that lies above and on the right side of Orion: we begin, well above Orion’s head, with Capella, the sky’s sixth brightest star, sometimes called “the Goat Star” because our ancestors saw it as a mother-goat surrounded by three fainter stars representing her family and known as “the Kids”. Capella is the brightest star in a large pentagon of bright stars known as Auriga, the Charioteer. In the middle of the western side of the half-circle is reddish Aldebaran, the “Eye of the Bull” star in the constellation Taurus, the bovine creature that Orion is attacking as he moves across our sky each night. Completing the semi-circle, is Rigel, the knee of Orion, and the seventh brightest star in the heavens. Though the two semi-circles do not form one perfectly symmetrical circle, they are actually fairly close to a circle, and they do contain, as already stated, four of the eight brightest stars, as seen from anywhere on earth. In addition, both of Orion’s “shoulder stars”, and one of his “belt stars” and the Twin stars, Castor and Pollux, are on the list of the 30 brightest stars. In summary, from the seven stars of the Great Winter Circle Around Orion, and the seven brightest stars of Orion himself, no less than 11 of those 14 stars are among the 30 brightest stars in the entire sky. This is, indeed, the great jewel box of winter gems!

Among the five bright planets, two of them may be seen very easily every clear evening, two of them every clear morning in February, and one of them may be seen early on clear evenings in the last half of the month very low in the western sky. The first planet to be seen in the evening by most people will likely be Saturn. In the evening twilight it appears well up in the east and about 10 degrees (the width of a fist held at arm’s length) to the left and downward from the Twin stars (Castor and Pollux) mentioned above. Saturn’s ring-system and its many moons are a beautiful sight for those who view it with a telescope. Careful observers will notice that it is at the southern edge of a large cluster of stars, called The Beehive Cluster, a group of stars that can even be seen naked-eye from the dark and unpolluted rural skies that many of us enjoy in this area. Very careful observers will also be able to note that Saturn appears to move slightly over the course of this month, being south of the centre of the star cluster at the beginning of the month, but to the southwest of the cluster by the end of the month. This westward or “to the right” movement is Saturn’s apparent “retrograde” motion. The normal movement of Saturn, like all the outer planets, is eastward or “to the left”, but Saturn now appears to “move backwards”, as the Earth passes this planet “on the inside”, and its retrograde motion will continue until April 5. The sight of Saturn within, and very close to, this large group of stars is very interesting in binoculars, and something that will not be repeated for another 59 years. Don’t miss it this month!

The next planet to be seen in the evening will likely be reddish Mars which is high in the southwest at nightfall, but Earth and Mars are not as close to each other as they were last October and November, and as they pull away from each other, Mars now appears smaller and fainter than it did at that time. Its movement now is much different and faster than that of Saturn. In the first week of February, Mars appears about midway between the famous Pleiades Star Cluster on its left and on its right the three brightest stars of Aries that now hang in the western sky like a hockey stick with its blade pointing downward and to the left. Try to note the forward or “to the left” movement of Mars as it seems to be approaching the Pleiades Cluster and will be quite close to that beautiful cluster by the end of the month. Mars ended its period of retrograde, or “backwards” apparent motion, almost two months ago, and it is now moving in its normal, or “eastward” and “to the left”, direction. Of all the outer planets, its movement is the most easily detected naked-eye. Mercury may be seen after about February 12, very low in the west each clear evening beginning about 45 minutes after sunset and until it sets about 30 to 60 minutes later. Be very sure to have a good view of the western horizon, unobstructed by any trees or buildings; that is the only way to be sure of seeing this planet this month. Careful observers will likely note that it appears a bit higher in the western sky each evening after it is first seen until by February 23, when they can watch it for about 90 minutes before it sets. After that, its height in the sky, along with its visibility time before setting, will gradually decrease. The two brightest planets of all are gems of the morning sky. Jupiter actually rises in the east about 1:00 a.m. and even before that in the latter part of the month. It is quite high in the eastern sky by the time of morning twilight. Venus rises in the east-southeast about 90 minutes before the sun, and during morning twilight, it is spectacularly brilliant. From those who rarely observe the sky and happen to spot it just by chance, there are bound to be some reports of “UFO sightings” in the early morning. The date of its greatest brilliance is a very technical one; it is actually the morning of February 17, but the difference in its brilliance on that morning from all other February mornings is extremely slight. It is certainly now bright enough to cast a shadow, and to be seen later in the day, especially if one wants to use the ‘trick’ of following its location in the sky from time of twilight until after sunrise. Try doing it.

Several lunar conjunctions with bright planets are worth viewing. On February 11, the Full Moon is near Saturn, and on the morning of the 20th the gibbous moon is near Jupiter. A very beautiful sight will be the morning sky views of the moon and Venus 40 minutes before sunrise on both the 24th and the 25th. The challenge I most anticipate is the sight of the thin Crescent Moon and Mercury very low in the west 40 to 60 minutes after sunset on both the 28th and March 1st.

More information about observing the winter sky is available in the book, The Beginner’s Observing Guide, now available at Sharbot Lake Pharmacy.