Star+Watch

“Star Watch” By: Cheyne Valeriote and Sarah Hampton __ What is a constellation? And who discovered them? __ A constellation is a group of stars that form a pattern or picture in the sky when they are seen from earth. Constellations were made up by astronomers, farmers and poets not discovered around 6,000 years ago to help them identify which star was which. Constellations divide the sky into convenient sections so that we can identify which stars are which. It is important to know this because often time’s stars can help you determine where you are and they helped people get places many years ago, they are used as mnemonics (memory aids). Constellations can also tell us which month it is, this was good for farmers because everyone knows that you plant crops in the spring and harvest them in the fall. Sometimes though, it was hard to tell when the seasons changed, especially when farmers lived in places where the climate does not change much at all. Many cultures also used constellations to tell stories about their gods. Constellations were also used as direction finders by people traveling in unfamiliar territory on land and sea. On a dark night you can see around 1,000-1,500, and every single one of them is a part of one of 88 constellations in the night sky.

__ Seasonal Constellations __

A seasonal constellation is a constellation that is only visible for a fraction of the year. Many constellations are seasonal; constellations that are not seasonal are called circumpolar constellations they circle the poles of the earth, instead of the whole earth. Seasonal constellations exist because the earth is always rotating. It takes stars a whole year to make a full 360 degree turn around the earth, they move about one degree westward every night. The most common winter constellation that we see is Orion, which is one of the easiest constellations to spot because there is a row of three stars that run in a row from east to west very close together, which make up Orion’s belt. There are four bright stars which make up Orion’s shoulders and knees, a small cluster of stars that shape a sword that hangs from his belt, and a bent line of dim stars outlines a shield that he holds above his head. The Big Dipper is the most common constellation, but it is not actually a constellation, it is an asterism which is a familiar group of stars within a constellation. The Big Dipper is a part of Ursa Major, or the great bear. It is visible in the Northern Hemisphere and can be seen all night on every night of the year, making it circumpolar. Andromeda is a seasonal constellation best seen in the fall; it is a “V” shaped constellation and is found next to Pegasus. There are many myths about Andromeda, one Greek myth tells the story of how her mother bragged that she was prettier than all the sea nymphs, so the sea nymphs complained to Poseidon and he ordered a monster to destroy her. Just as the monster was about to kill her, the maiden Perseus saved her. The legend goes that Perseus and Andromeda were put in the sky along with Cepheus, Cassiopeia and Cetus. Right beside Andromeda, is the Great Andromeda Galaxy which is the most distant point visible to the naked eye. 

__Recognizing Constellations__



Recognizing constellations is quite easy, all you have to do is look at their shape. For example, the Big Dipper is a well known star pattern. All stars in the big dipper are relatively bright, 3 stars mark the handle, and 4 mark the bowl. The big dipper is also part of a much bigger constellation called Ursa Major, the Great Bear. To find this constellation, look at the handle of the Big Dipper as the bear’s tail, the bowl as the back half of the body, the hind legs extend down from the bottom of the bowl, and the rest of the body and the triangular-shaped head extend off the front of the bowl. Just by playing connect the dots with the 7 bright stars of The Big Dipper and realizing its shape, you are then able to recognize an entirely new constellation. If you ever have trouble locating The Big Dipper, just know that if you take the 2 bowl stars, farthest from the handle, and draw a line with them that extends above the top of the bowl you will reach a moderately bright star, known as Polaris, the North Star.

__ Greek Mythology __ The Greeks contributed to astronomy by adding mythology. The Greeks were the first ancient people to name the constellations. The names that they gave the constellations were that of important figures in Greek mythology and with that, the constellations were perceived as divine. These figures were mainly Gods, Goddesses, Heroes, Heroines, and Warriors that these ancient people recognized and honoured. These included for example Orion, Scorpius, Andromeda, Aries, Capricornus, and many others. __

Stellar Brightness __ Stellar Brightness is a scale that ranks the stars in terms of their brightness as seen from the Earth. 1 represents the brightest, down to 6 representing the faintest. The scale was developed by Hipparchus, an ancient Greek astronomer. Apparent magnitude is how bright the star appears to us in the sky. A magnitude difference of 5 is set to exactly a factor of 100 in intensity. Absolute magnitude is how bright a star would appear from some standard distance, which is 10 parsecs or about 32.6 light years. Stars can be as bright as absolute magnitude -8 and as faint as absolute magnitude +16 or fainter. The brightest star is the sun, measuring in at an apparent magnitude of -26.72, and an absolute magnitude of 4.8. An example of this concept can be illustrated by using the star Spica. Spica is located 220 light years away from the Earth. Spica has a varying Apparent Magnitude of 0.98 and an Absolute Magnitude of -3.2. Spica has the Spectral Type B1V and is 17th on the list of the brightest stars as seen from the Earth.

Citations: [] [] [] [] []

Cheyne Valeriote: What is a Constellation? And who discovered them? Seasonal Constellations

Sarah Hampton: Recognizing Constellations Greek Mythology Stellar Brightness Citations