Most accurate from mid-northern latitudes of approximately 36-40 degrees, north;
(e.g. San Francisco, U.S.A. ** Madrid, Spain ** Tokyo, Japan)
Copyright (c) 1996 Pete Harris; **Back to Star Facts Home Page**
Updated for the month of: February 1996
Giant Question Mark in Northern Sky During February, around 7:30 p.m., the Big Dipper stands upright in the northern sky, appearing as a giant question mark. The Big Dipper is the most recognized shape in the sky. From most of the northern half of the Earth it never sets! It just goes around the North Star, making one giant circle each 24 hours. Even though the Big Dipper is one of the largest star shapes in the sky, it is only part of a still larger constellation called Ursa Major, or Big Bear (good luck seeing a bear - the people who named it must have been smoking some of that funny stuff). A recognizable shape, such as the Big Dipper, that is part of one or more constellations is called an "asterism".
The Big Dipper can save your life if you are ever lost at sea or in a wilderness area, by providing a way to determine which direction is north. The two stars at the dipper end (not the handle) are called the "pointers". They point to Polaris, the North Star. If you follow an imaginary line extending from the pointers 3 fist widths across the sky (the width of your fist with arm extended) in the direction of the open side of the dipper, you come to the North Star. It is not a bright star, but it is the brightest in that part of the sky.
Two Planets Pass in the NightOn February 2, 1996, Venus and Saturn pass each other on the path that planets travel across the sky, called the ecliptic. They are visible low in the southwest about one hour after sunset on that night, appearing very close to each other from our line of sight. Although this date is the night the two planets appear closest, they make an interesting sight from several days before this date to several days after. Venus begins this period below Saturn and ends up above Saturn after February 2.
Venus is by far the brighter planet, currently at a dazzling magnitude of about -4.0 , while Saturn is at a magnitude of about 0.4 (lower number means brighter, each whole number of magnitude represents a 2.5 times difference in brightness). This means that Venus is currently more than 50 times brighter than Saturn, even though Saturn is still brighter than most stars.
Actually Venus and Saturn are not close to each other at all. Saturn is currently on the other side of the sun from Earth and is hundreds of millions of miles further than Venus. Venus, whose orbit is closer to Earth's than any other planet's, is currently "catching up" to Earth on its inside track position in going around the sun. See entry below "Venus Gets Brighter as it Shrinks" for more information about Venus.
Sirius, Brightest Star and Champion
TwinklerSirius is the brightest star visible from Earth. Only some of the planets and the moon can outshine it in the night sky. It is known as the "Dog Star" because it is in the center of the constellation Canis Major, or Great Dog. February is probably the best month for observing Sirius during early evening hours. It comes into view around 6:00 p.m. low in the eastern sky and is highest around 9:00 p.m. in the southern sky. From mid-northern latitudes it is about one third of the way up from the horizon at its highest point. Sirius is the lowest and first star in a spectacular arc of bright stars currently visible called the "Great Arc of Capella" (see entry below "The Sparkling Stars of Winter").
Sirius is probably the star that inspired the nursery rhyme song "Twinkle, Twinkle, Little Star". It twinkles profusely, like a diamond in the sky. The lower in the sky it is when you observe it, the more dramatic its sparkle, as its bright light passes through a thicker layer of Earth's air. The reason Sirius is the brightest star of all, has more to do with its relative proximity to Earth, than its size or intrinisic brightness. Sirius is "only" 8 light years away from Earth, the fifth closest star. It has a diameter of 1.8 times that of our sun.
Sirius is part of a double star system, two stars in each other's gravitational field, rotating around each other. It has a small, faint, elusive companion called Sirius B, or the "Pup". It takes Sirius and the Pup 50 years to rotate around each other. The Pup is a white dwarf star - a "dead" star that has run out of hydrogen fuel to burn and has collapsed in on itself, shining only because its temperature remains high. As it cools it will eventually become a black dwarf - dead, cold and invisible from Earth. The Pup is an incredibly dense object thought to be only 30,000 kilometers in diameter, with each cubic inch of this star weighing over 2 1/2 tons!
The Sparkling Stars of WinterLooking like icicles hanging in the moonlight, the bright stars of winter fill the sky. If you like bright stars, winter is the time for you.
In the center of a glittering array is the awesome constellation Orion, the symbol of winter. From mid-northern latitudes in February, 1996, Orion becomes visibleas it turns dark in the southeastern sky and is best seen between about 7:00 p.m. and 9:30 p.m., when it appears about half way up from the southern horizon. Orion is defined by its line of three bright stars in a row that form Orion's Belt. Supergiants Betelgeuse (popular pronounciation: "beetle-juice") and Rigel, known as Orion's shoulder and heel, are symmetrically spaced above and to the left, and below and to the right of the "belt" (see entries that follow about Betelgeuse and The Great Nebula in Orion). The right-most star in the "belt" falls right on the celestial equator, the imaginary line that circles directly above the Earth's equator. To an observer at the equator this line passes directly overhead, the point known as the zenith. To all others not on the Earth's equator, this line is as many degrees south or north from the zenith as the observer's latitude - distance in degrees from the Earth's equator.
Forming a Great Arc of brightness around Orion (known by some as the "Great Arc of Capella") are six of the brightest stars in the heavens. This Great Arc begins with Sirius, the brightest of all stars visible from Earth. Sirius is found by following the line of Orion's Belt about two fistwidths down and to the left. Curving up and around Orion from Sirius to complete The Arc are Procyon, Pollux and Castor ( the Gemini twins), Capella, and Aldebaran (the "eye" of Taurus the Bull).
The stars of winter are not as densely packed as the stars of summer. During summer nights we face mostly in the direction of the central parts of our Milky Way galaxy, where the stars appear most concentrated, but extend out further away from us. During winter nights we face mostly in the direction out of our galaxy, above and below the Milky Way disc, out the near edges and toward the edge of the spiral galaxy arm we are in. There are less stars to be seen there. However, the stars we do see in winter tend to be brighter, younger, hotter and bluer, and more spectacular.
The Great Nebula in the Hunter's SwordHanging underneath the left-most star in the line of three bright stars that form the famous "belt" of the mythical Orion the Hunter, is a dim, diagonal, somewhat fuzzy line of light. This is known as the Hunter's Sword. On clear winter nights three dim stars in the sword are visible with the naked eye.
Look at the sword with binoculars and you see three pairs of stars, the middle pair appearing to glow in a fog-like area. With a low or medium power eyepiece on a telescope you see a celestial wonderland of glowing swirls and streamers of intersteller gas, with brighter concentrations and dark, black regions. Glowing inside the misty mass are several bright stars, shining like beacons in the fog. You are seeing one of the most beautiful and exciting sights in the heavens. This is a nebula, known as the "Great Nebula in Orion", also classified as M42. (See beautiful time-exposure photo of the Orion Nebula on Jason Ware's website). It is a star nursery containing newly formed "baby" stars. Still others are being created as we look at it. It is a star cluster in the making. See Star Facts article for January, 1996, "How and Where Stars Are Born" for more complete explanation.
To find Orion see instruction in the previous entry.
Betelgeuse, the Red SupergiantAbove and to the left of the line of three bright stars that form the famous Orion's Belt is a bright reddish star named Betelgeuse (popular pronounciation: "beetle-juice"). Betelgeuse is a red supergiant. It is another example of a dying star that has become bloated in its last stages of life.
Betelgeuse, which is about 300 light years away, is so large that if it were our sun it would engulf the planets Mercury, Venus, Earth and Mars. We would be inside it! It is a variable star, unstable in size, that fluctuates erradically in brightness during a period of about 6.4 years.
It is interesting to contrast the reddish color of Betelgeuse with Rigel, another supergiant star in Orion. Rigel, about 900 light years away, is located below and to the right of Orion's Belt. It is a blue supergiant, on the other side of the color spectrum of stars from Betelgeuse. The color difference is dramatic when seen with binoculars. Bluish stars are the hottest. Reddish stars are the coolest.
Venus Gets Brighter as it Shrinks!Between January and June 1996, the planet Venus presents a spectacular sight in the southwestern sky during the first 1 to 2 hours after sunset. Other than the Sun and Moon, Venus is the brightest object in the sky. It will continue getting brighter during the next few months as it races around the Sun on an inside track to the Earth's orbit, and "catches up" to us in June, 1996. (See "Solar System Live" website to see relative positions of the planets, click on "inner planets", blue circle is Earth, white circle is Venus).
Because Venus, our next door neighbor in space, is closer to the Sun than Earth is, we see it going through phases that are similar to the Moon's phases. When it is on the opposite side of the Sun from Earth we see it far away but full-face, a "full Venus". When there is approximately a 90 degree angle between Earth, Sun, and Venus, as is almost the case at the beginning of February, 1996, we see a brighter "half Venus". As Venus catches up to Earth in its orbit and comes close to lapping us on its inside track, we see an even brighter "crescent Venus". So Venus gets brighter as it comes closer to Earth, even though the part that we see lit up is shrinking.
To see the phases of Venus you need a good pair of binoculars or a small telescope. Keep an eye on it between now and June, and you will see an exciting progression of changes.
Seven Sparkling Jewels in the NightWinter brings a sparkling little group of stars into the night time sky, called the Pleiades (pronounced PLEE-ya-deez); also known as M45. The Pleiades is a star cluster made up of over a hundred stars. The seven most prominent members, visible to the naked eye as a tightly packed little group, and arranged in the shape of a little dipper, give the cluster its nickname: the Seven Sisters. (See beautiful time-exposure photo of Pleiades Cluster on Jason Ware's website.) In February, from mid-northern latitudes, the Pleiades is almost directly overhead as darkness falls, and continues toward the western horizon, setting around midnight.
The Pleiades, one of the closest star clusters to our Sun, is about 400 light years away. Its stars are not just an apparent grouping from our angle. They are a star system, held together by mutual gravitational attraction, with its largest members all within a space of about seven light years of each other. On the grand clock of the universe these are baby or adolescent stars, "only" about 50 million years old (our Sun is about 4 1/2 billion years old). They are a "litter" born of the same intersteller cloud of gas, still huddled together until they get older and begin to go their own way in the universe.
The Pleiades is best seen with the naked eye or with binoculars, so that the whole cluster can be seen in one field of view. With a large amateur telescope whisps of nebulosity, like breath on a mirror, can be seen around some of the brighter stars. This is the embryonic remains of the gas cloud of which the cluster was created.
Cassiopeia the QueenLike a giant and slightly squashed letter "M" in the sky, the constellation Cassiopeia, known as the Queen, stands almost upright during early evening hours in February. As you face north when darkness falls it is above and to the left of Polaris, the North Star. It circles toward the west and down as the night goes on.
Cassiopeia was named by the ancient Greeks after a character in Greek mythology. Cassiopeia was married to Cepheus, the King of Ethiopia (who has a constellation of his own, next to Cassiopeia that looks like an upside-down house). When Cassiopeia boasted that her daughter, Andromeda, was more beautiful than the sea nymphs, Neptune became angry and had Andromeda chained to a rock near the home of a terrible sea monster. Just as the monster was about to devour her, along came Persues on the flying horse (stay with me here, we're coming to a conclusion). He was carrying the snaky-haired head of Medusa, a horrible creature that he had slain. The monster turned to stone when he saw the head and Andromeda was saved (whew!).
From mid-northern latitudes Cassiopeia is one of the constellations near the North Star that never sets. As the Earth spins around once every 24 hours, Cassiopeia makes a giant circle around the North Star, going one twenty-fourth of the way around each hour. If you compare it at the same time during each season, it goes one quarter of the way around each season.
The Full MoonThe next full moon occurs on the night of February 4, 1996. The moon is full when it is on the opposite side of the Earth from the sun, so that the part of the moon that faces us also faces the sun. Therefore, at the time of a full moon, the moon rises in the east at the same time that the sun sets in the west.
The best times to view the moon with binoculars or telescope is definitly not around the times of a full moon. It is during the times when the moon is in the crescent to half moon shape. It is at this time that the shadows on the moon are the longest, making the craters and mountains on the moon more visible and three dimensional. The best place to look is around the areas where the light and dark sides of the moon meet. This dividing line, called the "terminator", is where sunset or sunrise is occuring on the moon, and shadows are the longest.
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