WHAT'S UP there DOC

- a guide to current sights and events in the evening sky

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: January 1996

The Sparkling Stars of Winter

Looking 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 January, 1996, Orion becomes visible around 7:30 p.m. in the southeastern sky and is best seen between 9:30 p.m. and 11:00 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 Sword

Hanging 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 Supergiant

Above 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!

During January, 1996, and the following several months, the planet Venus presents a spectacular sight in the southwestern sky during the first 1 to 1 1/2 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 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 occurs by the end of January, 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.



Crescent Moon and Two Planets
Define an Important Line

On January 22, 1996, about one hour after sunset, a crescent Moon and the planets Venus and Saturn make a pretty sight low in the southwestern sky. The crescent moon will be the lowest of the three, followed by a very bright Venus and dimmer Saturn, all in roughly a diagonal line coming up from the twilight at the western horizon. Watch for the Earthshine reflecting off the part of the Moon that is not lit by the Sun.

The imaginary diagonal line that runs roughly through these three objects is the western end of the ecliptic. The ecliptic is the approximate path of the planets, Moon and Sun across the sky. If you extend this line in your mind as an arc that runs back and up through the southern sky and down into the southeastern horizon, you have defined this path. Because all the planets orbit the sun in approximately the same plane, from our point of reference all the planets and Sun follow roughly the same path across the sky. This path is the only place you look to see planets - they won't ever be anyplace else. Since the Moon orbits the Earth at only a slight angle to the plane of the planets, it too is always found close to the ecliptic. The ecliptic also runs through the so-called twelve constellations of the Zodiac, the constellations that form the background to the path of the Sun. That is why the planets are always said to be "in" or "passing through" one of these constellations.

During the year the position of the ecliptic at night gets higher and lower from the southern horizon in an opposite pattern to the Sun's daytime path across the sky. This is due to the Earth's tilt and yearly movement around the sun and the fact that at night we face the opposite direction from the direction we face in the daytime. In winter, when the sun's daytime path is lowest, the nightly position of the ecliptic is highest. The opposite is true in the summer.



Seven Sparkling Jewels in the Night

Winter 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 January, from mid-northern latitudes, the Pleiades comes into view in the eastern sky around 6:30 p.m., crosses almost directly overhead around 8:30 p.m., and continues toward the western horizon, setting around 2:00 a.m..

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 Queen

Like a giant and slightly squashed letter "M" in the sky, the constellation Cassiopeia, known as the Queen, stands upright during early evening hours in January. As you face north it is almost directly above Polaris, the North Star, around 6:00 p.m. and 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.



Watch the Demon Star Get Dimmer

The star Algol, meaning "Demon Star", belongs to one category of variable stars called "eclipsing variables". (See Star Facts article for October, 1995 The Mysterious Demon Star Dims...Then Brightens for fuller explanation). Variable stars change their brightness over a period of time. Algol gets dimmer approximately once every 2 days and 20 hours. It stays near its dimmest for about 2 hours, with the entire fading and brightening process lasting about 7 hours.

Algol is best seen beginning in autumn and into winter. It is found in the northern constellation Perseus. See diagram below for graphical representation of Algol's position relative to Cassiopeia. The easiest way to find it is to face north and locate the constellation Cassiopeia, which looks like a giant and slightly squashed letter "M" in the northern sky. During early evening hours in January the "M" is standing upright above the North Star. Extend the imaginary line from the "M" 's bottom center point to its top right point about 1 1/2 fist widths further (width of closed fist with arm extended) to a region to the upper right of the "M". In this region find a fairly bright star (not quite as bright as the stars that form the "M") in the center of a group of stars with no clear shape, this group is the constellation Persues. Algol is found a little less than 1 fist width above this central star. Algol, in its bright state is about the same brightness as the central star.



To see Algol's changes in brightness use binoculars to look at it during a period of several nights. Compare it with one or two surrounding stars of similar brightness. Make a sketch on a piece of paper with some notes about the relative brightness of Algol to the other stars. See how the observations change over time. At its dimmest, Algol should be about half the brightness that it is most of the time. See if you can catch it at one of its dimmest points.



Andromeda, "The Great Galaxy"

Andromeda, shown as M31 on star charts, and known as the "Great Galaxy", is a galaxy 2.2 million light years away from the Milky Way, made up of hundreds of billions of stars. It is the furthest object in the universe that can be seen with the unaided eye, although that is only possible from very dark, clear locations. It is quite visible with binoculars or a low power eyepiece on a telescope. (See Star Facts article for September, 1995, The Andromeda Galaxy - the Most Distant Thing Human Eyes Can See" for further description).

Andromeda continues to be in a good position to be seen in January. It is found in the constellation that bears its name - Andromeda. The easiest way to find it is to face north and locate the constellation Cassiopeia, which looks like a giant and slightly squashed letter "M" in the sky. During early evening hours in January the "M" is standing upright above the North Star. Using the left half of the "M" as an imaginary arrowhead, go about 1 1/2 fist widths (the width of your clenched fist held up to the sky at arm’s length) in the direction the arrowhead points in. Scan this area with binoculars to find the fuzzy patch of light that is Andromeda. Sweep back and forth over the area until you begin seeing its dim outer regions that give it an oval shape. (See beautiful time-exposure Photo of Andromeda from Jason Ware's home page).



The Full Moon

The next full moon occurs on the night of January 5, 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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