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Guiding your celestial way on the longest night

Looking for something to keep you busy on the longest night of the year? Contributor Tom Callen offers a guide to reading the stars above Sweden during the winter solstice.

Guiding your celestial way on the longest night

Do you find the night sky confusing? If so you’re not alone. The heavens initially look like a cluttered jumble of tiny points of light, but with a little practice you can find your way around just as the ancients did.

Fortunately winter nights hold some of the best and the brightest of all the constellations. And with today, December 22nd, being the longest night of the year you’ll have plenty of time to look.

Seasonal skies often have one constellation that serves as a key for helping to find our way around and this month contains one of the best examples; Orion, the Hunter. And unlike many such figures it also resembles the mythological character it’s named after.

Facing southeast your eyes will probably be naturally drawn to a line of three stars of similar brightness that are fairly close together. This is the “belt of Orion” and it sits in the center of an elongated rectangle whose four corners are marked by bright stars, one of which, Betelgeuse, is conspicuously red-colored.

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It marks the giant hunter’s right shoulder, which is confirmed in the star’s name as when it’s translated from Arabic means “armpit of the mighty one.” While not very flattering it is in fact functional. Orion’s right arm raised over his head is wielding a large club that he uses while hunting and his left arm is stretched out in front with an old lion skin draped over it as a form of shield. Crossing diagonally down to the right from Betelgeuse and we find bright blue-white Rigel in his left ankle.

Returning to the three belt stars and following them down diagonally to the left you will find dazzling Sirius – the famous “Dog Star” – at the tip of the nose of Canis Major, the Large Dog. This is the brightest star in the nighttime sky, but only because it’s relatively close to us at its distance of 8.6 light years. This means that its light has taken almost nine years to reach us, so as you gaze at it this month that light started its travel earthward in 2002 and this a relatively close star!

Let’s use Orion’s belt again, but this time travel up and to the right where we come across orange-red Aldebaran, the right eye in the v-shaped face of Taurus, the Bull. Known for some 4,500 years, it is one of the oldest constellations. Like Orion, Taurus bears some resemblance to its namesake complete with a pair of very long horns.

A line extending from Orion’s left ankle (Rigel) and out from his right shoulder (Betelgeuse) bring us to our next group; Gemini, the Twins. Its look-a-like stars, Pollux and Castor, were named to honor the twin brothers who sailed on the mythological quest with Jason and the Argonauts. Gemini has the distinction of having two famous modern solar system bodies discovered in it; Uranus in 1781 by William Herschel and Pluto in 1930 by Clyde Tombaugh.

The last and certainly the least of our constellations lies between Gemini, tonight’s Moon and the horizon. Canis Minor, the Little Dog, is one of the smallest constellations, consisting of essentially two bright stars and a smattering of faint ones. You will know that you have found it since its brightest star, Procyon, makes a perfect equilateral triangle (known as the Winter Triangle) with Sirius and Betelgeuse. Procyon is a Greek name meaning “before the dog,” which is appropriate since it rises above the horizon about an hour and 45-minutes before the Dog Star does.

The Moon is shown for December 22nd, but is also faintly marked at the same time for the next three nights so that you can see just how much our natural satellite moves per day.

If you happen to own a pair of binoculars take them out on a clear night and slowly sweep them around the sky. There are easily far more stars than can be seen with the naked eye. Take a look at the Moon; you’ll see thousands of impact craters and large dark patches of what was once molten lava that flowed out from its interior billions of years ago.

Three other objects of optical interest can also be easily found. Below Orion’s belt hangs a faint naked eye “sword.” Looking at the dull spot in its center you can see a grayish-green haze. This is the famous Orion Nebula, a gigantic cloud of gas and dust where stars are known to be in the process of forming.

Astronomers estimate that in the part that’s glowing there is enough material to form about 10,000 stars like our own Sun. Moving on, the v-shaped face of Taurus is actually a cluster of stars, the Hyades, that all formed together out of a nebula similar to that in Orion. Lastly, just above Taurus’ back, is a beautiful cluster of stars that are known as the Pleiades, or Seven Sisters. They too are a cluster like the Hyades, though they lie some three times farther away from us and as a result look smaller and more compact.

When stargazing be sure to dress warmly and bring along a thermos of something hot and nonalcoholic to drink (alcohol can affect your eyes’ dark adaptation). Protect your night vision by using a lit flashlight with a piece of red gel taped over its lens, or by putting your flashlight into a red plastic, or a brown paper, bag. Any of these will help cut down on the flashlight’s brightness while allowing you to see the black and white version of the sky map that you can print out to take with you.

Should it be cloudy on December 22nd you can still use the same map again on a night that’s clear. Each evening the same stars rise a little earlier so that after one week (December 29th) it will look the same as the map at 21.00 while two weeks later (January 6th 2011) at 20.30.

Editor’s note: the winter solstice occurred at 12:48am on December 22nd Swedish time, but the longest night of the year in Stockholm will occur from Wednesday to Thursday, December 22nd to 23rd.

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STARS

Vernal equinox provides celestial proof of spring

For long suffering residents of Sweden, Sunday's vernal equinox brought with it celestial proof that spring is indeed on its way, contributor Tom Callen writes.

Vernal equinox provides celestial proof of spring

Sandwiched halfway between the shortest day of the year (December’s winter solstice) and the longest (June’s summer solstice), the vernal equinox is proof of Earth’s motion around the Sun and more importantly for those of us who live at high northern latitudes, that warmer and sunnier days are finally on their way.

The word “equinox” sounds very much like “equal” and has in fact that meaning; days and nights are now roughly about the same length in hours and the coming days will get longer and the nights shorter as we head toward summer.

In short while the northern hemisphere looks forward to summer, the southern hemisphere has their autumn and winter ahead.

Though it is now astronomically spring there are still many traditional winter constellations visible beginning in the southwestern part of the night sky, but their days are numbered.

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Looking at the color sky map we can see one of the westernmost of these, Canis Minor, at its upper right edge. With the coming of spring we have other constellations related to this annual time of renewal.

Leo, the Lion, is one of the most dominating figures of the season and he is easy to find; just look for the large backwards “question mark” in the southeast. Some liken its shape to the harvester’s sickle used to cut stalks of ripe grain.

Another, more colloquial method of locating Leo is to imagine the well-known Big Dipper full of water. If you punch a hole through its bottom, the water will run out and if you listen you should hear a mighty roar as you’ve dumped it onto the head (the top of the backwards question mark) of the so-called “King of Beasts.”

However you find it, that question mark is the lion’s mane (the curve), chest (the straight line below the curve) and heart (the bright star Regulus that is the question mark’s period). The reclining right triangle to the left is the haunch of the lion’s right leg so this maned majesty’s final appearance looks not unlike the Great Sphinx of Giza in Egypt.

Regulus, which means “little king,” was supposedly named by Nicolaus Copernicus (1473 – 1543), the same astronomer who re-proposed that the Sun was the center of the solar system and that the planets orbited it.

Appearing single to the eye Regulus is actually two pairs of stars in orbit around each other. Since this bright star lies so close to the plane of the solar system it is often occulted, or covered, by the Moon as it moves through this part of the sky; it can even more rarely be covered by the planets Mercury and Venus and even more rarely still by some asteroids.

Denebola, the brightest star in the triangle that marks the lion’s right haunch, has a name that actually tells us something about its position. It is derived from an Arabic phrase that means “tail of the lion” and in verbal descriptions of this group Leo’s tail loops down from his body and then up again with Denebola marking the tufts at its tip.

Saturn lies low in the east southeast this time of year near Virgo, the Virgin’s, star, Porrima. If you look carefully you will note that while stars twinkle, or scintillate, due to turbulence in Earth’s atmosphere, the planets do not. Watch yellowish-white Saturn over the coming weeks as it appears to slowly move closer to Porrima, a combination of the ringed planet’s and our own world’s motion around the Sun.

While looking at this part of the sky your gaze might easily be captured by the colorful and dazzling Arcturus in Boötes, the Herdsman.

Poised over the eastern horizon to the left of Porrima and Saturn, you can be sure you have found it by using an old star-finding rhyme as I myself learned it many decades ago. Find the Big Dipper and then use its curved handle, or “arc,” and “follow it to Arcturus.”

Believe it or not planetariums receive many calls this time of year from people seeing “UFOs” in this part of the night sky and more than likely the culprit is Arcturus, which may hold the record for being the one celestial object most confused for an extraterrestrial spacecraft. But like the other stars it is merely scintillation that provides this annual light show.

Arcturus’ light was used to open the World’s Fair held in Chicago in 1933. Focused onto a photocell at the inaugural ceremony it signaled the grand opening.

Unfortunately the Fair’s organizers had been erroneously told that the light from Arcturus seen in 1933 had left at about the same time as the previous world’s fair (1893), which was also held in Chicago. However, being 36.7 light years away its light had actually left in 1896 and not in 1893. No matter, the public of the day was greatly impressed with this feat of modern technology all the same.

Last, and certainly least in this case, is the faint group known as Coma Berenices, the Hair of Bernice.

Laying between Leo and Boötes it becomes more interesting if you sweep across it with a pair of binoculars. By doing so you’ll then be able to see a myriad of stars that are, according to legend, supposed to be the silky tresses of this ancient Egyptian beauty. Though the modern constellation itself did not come about until the 16th century.

Besides March 21st at 8.30pm the sky map can also be used in the weeks ahead – on March 28th at 8pm and April 4th at 7.30pm.

Protect your night vision by using a lit flashlight with a piece of red gel taped over its lens, or by putting your flashlight into a red plastic, or a brown paper, bag. These will help cut down on the flashlight’s brightness yet allow you to see the black and white version of the sky map that you can print out to take outdoors.

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