How Do You Read an Astronomy Star Map?


Quick Answer

Read a star map by orienting yourself in one of the four cardinal directions, holding the star map in front of yourself and rotating it so that the direction you are facing points toward the ground. Find the brightest star, and match it with the largest circle on the map.

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How Do You Read an Astronomy Star Map?
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Full Answer

Star maps work differently from regular maps because they have to represent a three-dimensional space, the night sky, on a two dimensional surface. Pointing the map downward along the same direction you are facing shows you only that portion of the sky visible from that vantage point. If you rotate your body, you must also rotate the star map accordingly, or it does not give an accurate picture of the sky.

Use the right star map for your area of the Earth and time of year. Because the Earth is a round body and because it constantly orbits the sun, people in different places see different parts of space throughout the year. Different star charts are available for astronomers in the northern and southern hemispheres. While the night sky technically changes each day, most publishers only print monthly star charts because daily changes are very small.

Try to find the brightest stars in the sky and match them with the largest circles on the star map. Not only are the brightest stars the easiest to find, but many dimmer stars may be obscured or completely invisible in areas with many electric lights.

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