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Best time to observe: December - March
In winter, find Orion high above the southern horizon. Down and to the left of Orion is a very bright twinkling star. You've located Sirius, the brightest star in the night sky.
Normally stars aren't very interesting to observe in a telescope, unless they are multiples and you can "split" them. You're looking at Sirius not because it's a multiple star (it is, but it's companion is much too tiny to see) but because it can help you learn about your telescope. Practice targeting your Telrad finder on Sirius. While looking in your eyepiece, try moving the telescope around, bringing the star in and out of your field of view. You'll find that the telescope and the objects you are viewing don't appear to move the same way! Also, center Sirius then leave the telescope alone for about 2 minutes. When you come back, what has happened to the star?
What color is Sirius? Also notice that it twinkles a lot. Twinkling occurs as starlight pierces our atmosphere and is slightly refracted by the air masses. Sirius twinkles more than most stars because it happens to be low in our sky so it's light travels through more atmosphere than stars directly overhead.
In the 4H telescopes, notice that Sirius seems to have 4 bright rays extending from it. This is actually light being diffracted around the spider in your telescope!
Sirius is a hot, blue star 22 times brighter than our Sun. But its apparent brilliance results from its being closer to the Earth than most other stars (only 8.6 light-years). Sirius is actually a part of the "Ursa Major Group" of stars which makes up our Big Dipper. These stars are traveling together in space, although Sirius happens to have taken a path on the other side of our Sun than its companions.
Sirius has a tiny companion, a white dwarf much too small and dim to see with your telescope. White dwarves are the remains of old stars which have used up most of their fuel and collapsed. These collapsed remnants are so dense that a piece of this star's material the size of a tennis ball would weigh as much as two elephants.
In ancient Egypt, Sirius was worshipped as the Nile Star, because its appearance in the predawn sky in late June heralded the beginning of the annual Nile flood.
The Sun and Sirius rise together in the sky during the hottest part of summer. In the Middle Ages it was believed that the combined light of these two objects produced that period of excessive heat. Since Sirius was also known as the Dog Star, the peak weeks of summer's heat came to be known as the Dog Days of Summer.
One one of your observing pages, sketch how Sirius looks through your telescope.
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