Published on November 13, 2007
Slide1: Constellations Slide2: A pattern or group of stars in the sky is called a constellation. People of ancient time saw the constellations as character or animals in the sky. They made up stories to explain how the object, animal, or character came into the night sky. Slide3: Orion Orion is one of the brightest constellations and is a mythological character. According to Greek myths, Orion was a hunter who used to brag all the time. This bother the gods. When the gods were tired of him, the sent a scorpion to bite and kill him. The gods felt bad for doing having Orion killed, they they placed him in the sky. Slide4: Stars as Tools for Navigation Earth rotates on its axis, this makes most constellations appear to rise in the east and set in the west during the night. Most constellations appear in many different positions in the sky as the Earth revolves around the sun. There is a group of stars that appear in the sky all night long and all year long. It seems that these stars do not rise and set, but circle the Earth’s north pole each night. These stars are called circumpolar. Slide5: Stars as Tools for Navigation The North Star is called Polaris and located directly above the North Pole. This star appears in the same place every night all year long. In the Northern Hemisphere, if you find Polaris you will be able to tell which direction is north. The Southern Hemisphere does not have a star to help you find its pole. In stead it has what is known as a Southern Cross. The Southern Cross consists of 4 bright stars and some dimmer ones. All of these together point to the south pole. Slide6: Stars As Calendars It seems that the constellations in the east rise a little earlier each evening. This means that the seasons are changing and we are seeing different constellations. An example is in the Northern Hemisphere, Orion is high in the sky during the winter and Scorpio can only be seen during the summer. People of ancient times used these seasonal changes in the stars as calendars. It is believed that the ancient people used the constellations to tell them when to plant and harvest crops. An example would be Leo and Virgo in the night sky would signify that the last frosts of the year have happened and it is safe to plant. This worked much like our paper calendars work for us today. Slide7: The brightest constellation is Crux (the Southern Cross). The constellation with the greatest number of visible stars in it is Centaurus (the Centaur - with 101 stars). The largest constellation is Hydra (The Water Snake) which extends over 3.158% of the sky. Slide8: 1. What is a constellation? 2. Why is Polaris called the North Star? 3. How did ancient people use the seasonal appearance of certain constellations? 4. Name two constellations.