Winter Sky Splendour

For mid-northern latitudes it is the time for a changing of the seasonal skies. Just after dark during early December nights, we can still see the late summer stars in the western sky. It is not yet officially winter and the winter stars have only just begin to peek over the eastern horizon at dark but by later in the night they offer a good preview. December offers a variety of planets and there is a whole host of objects for small telescopes and binoculars.

The Summer Triangle of Vega (in Lyra), Altair (in Aquilla) and Deneb (in Cygnus) are still quite high above the western horizon at the onset of darkness. Pegasus is overhead and it is still a good time to view the Andromeda Galaxy nearby in Andromeda.

The southern sky is rightly described as the watery portion of the heavens. It is not a particularly bright region, the brightest star being Fomalhaut in the Southern Fish (Pisces Austrinus.) This area of sky is also inhabited by Capricornus the sea-goat, in which Neptune currently resides. Capricornus is above and slightly to the west of Fomalhaut.

Pisces Austrinus can be found at http://starryskies.com/The_sky/constellations/pisces_australis.html
Capricornus can be found at http://starryskies.com/The_sky/constellations/capricornus.html

Stretching above both the Southern Fish and Capricornus is Aquarius the water-bearer. East of Aquarius is the large and dim constellation of Pisces. Between Pisces and Aquarius is Mars, but the red planet is much dimmer than it was in August. Below Pisces is another large and dim water creature, Cetus the Whale, swimming on the southeastern horizon. Our last watery creature can be found above and to the east of Altair. There you will find Delphinus the dolphin, a constellation so small it can be covered by your fist held at arms length.

Aquarius can be found at http://starryskies.com/The_sky/constellations/aquarius.html
Cetus can be found at http://starryskies.com/The_sky/constellations/cetus.html
Delphinus can be found at http://starryskies.com/The_sky/constellations/delphinus.html

In the northern sky, the Big Dipper is low in the sky, passing below the horizon for all but the far northern latitudes. Of the circumpolar constellations, Cassiopeia and Cepheus are very high in the northern sky. If you are new to finding Cassiopeia, the group of stars forms a distinctive "M" or "W" depending on its orientation in the sky, currently it is an "M". It can also be useful in helping locate Andromeda, which is above and slightly east of Cassiopeia.

Cassiopeia can be found at http://starryskies.com/The_sky/constellations/cassiopeia.html
Cepheus can be found at http://starryskies.com/The_sky/constellations/cepheus.html
Andromeda can be found at http://starryskies.com/The_sky/constellations/andromeda.html

Winding his way above the Big Dipper and to the west of the Little Dipper is Draco the dragon. It too is a dim constellation but its claim to fame is its brightest star, Thuban. Around 3000 BC, when the Great Pyramid was being built, Thuban was the pole star. Temples were aligned to Thuban and one of the shafts in the Great Pyramid points to Thuban.

Draco can be found at http://starryskies.com/The_sky/constellations/draco.html

The pole stars change over time due to precession, or wobbling of the Earth's axis. To understand precession, think of how a spinning top wobbles, tracing out a small circle. One effect of precession is a gradual changing of the positions of stars as seen from our position on Earth. One cycle takes 26,000 years. Currently of course, Earth's axis points to Polaris but a long time ago, it pointed to Thuban and in the far future, it will point to Vega.

Just above the eastern horizon after dark is a small but distinctive cluster of stars called the Pleiades. The entire cluster can be covered by your fist held at arm's length. The Pleiades lead the parade of winter stars. This cluster, also known as the seven sisters, belongs to the constellation Taurus the bull.

The Pleiades have a rich history with many cultures. It is both interesting, and puzzling that while they are called the seven sisters, only six stars are visible to the naked eye. Some of the many myths explain why the seventh star is not visible such as this one from the Onondago which hints that the seventh star may have been brighter at one point, which astronomers believe is possible. http://starryskies.com/The_sky/constellations/pleiades.onondaga.html

Or this beautiful story about the Pleiades from the Polynesians: http://starryskies.com/The_sky/constellations/pleiades.polynesian.html

By 9:30 pm EDT, the winter star parade is in full swing. The Pleiades are almost overhead and Taurus is in a good position for viewing. There is a second star cluster in Taurus, the Hyades. The stars of the Hyades are most scattered than those of the Pleiades but they are marked by the brightest star in Taurus, yellow Aldebaran which represents the eye of the bull. This is a giant star, 45 times that of our Sun.

Taurus can be found at http://starryskies.com/The_sky/constellations/taurus.html

Above Taurus is a bright white star, Capella in the constellation Auriga the Charioteer. Auriga contains several star clusters that look nice in a small telescope. Capella is the fourth brightest star in the sky but it is actually the blended light of two giant stars! The two nearly identical stars orbit their common center of gravity at a separation about equal to the distance between the Sun and Venus.

Auriga can be found at http://starryskies.com/The_sky/constellations/auriga.html

Below and a bit north of Taurus is Gemini the twins. The two brightest stars of Gemini are Castor and Pollux, marking the heads of the twins. Pollux is slightly brighter than Castor. If you have binoculars, take a look at Castor, it has three visible companions. And around the foot of Castor is M35, a lovely cluster of about 1200 stars. Currently, Mars is residing in Gemini. Though it's still fairly bright, Mars has dimmed noticeably from its' August splendour.

Gemini can be found at http://starryskies.com/The_sky/constellations/gemini.html

Below Taurus is the unmistakable Orion. No other constellation has so many bright stars! There are four bright stars making a rectangle which mark the shoulders and knees of Orion the hunter. The brightest of the four, Betelgeuse is a beautiful red supergiant, of enormous proportions. Betelgeuse is a variable star, the brightness changing as the star expands and contracts, ranging between 700 and 1000 times the diameter of our Sun! Betelgeuse is in the final stages of stellar evolution and will soon end as a supernova.

Diagonally opposite to Betelgeuse is the bright blue Rigel, a blue supergiant of a star. Rigel is one of the most luminous stars known, if it was as close to us as Sirius (8.5 light years) Rigel would shine 150 times brighter than the planet Venus!

Perhaps the best known feature of Orion is the great nebula M42. To find it, use binoculars or a telescope and look below the middle belt star. This nebula which is about 1500 light years distant, is an area of star formation. This area of gas and dust is one of the most spectacular sights through a telescope.

Orion can be found at http://starryskies.com/The_sky/constellations/orion.html

Later in the night, the brightest star in the night sky has risen above the east-southeast horizon: Sirius. This brilliant star belongs to Canis Major, the greater dog. Sirius is bluish white in colour, but it is not so bright because it is large like Rigel. Sirius is bright because it is so close to us, 8.6 light years away. In ancient Egypt, Sirius was worshiped as the Nile star. Around 3000 BC, the appearance of Sirius in the predawn sky around June announced the beginning of the annual Nile River flood. Sirius has a companion, called Sirius B (sometimes called the pup) visible in binoculars.

Canis Major can be found at http://starryskies.com/The_sky/constellations/canis_major.html

If you happen to be up early on Christmas morning there's a few things to look for in the sky before sunrise. The bright star almost overhead is Arcturus in Bootes the herdsman. Arcturus is a yellow giant, one of the closest to our Sun at 36 light years. About halfway up in the southwest sky is Jupiter, currently residing in Leo the lion. Mars, in Gemini is just setting on the western horizon.

And there's something to watch for later Christmas day, at sunset. On that day the Moon and Venus are very close to one another. And though you can't see it with the naked eye, Neptune is also close by. All three are in Capricornus that night but you have to catch them right after sunset.

Happy Stargazing!

Constellations

The Solar System