Question

Suppose a student takes a study break from astronomy homework and steps out onto his or her balcony on a fall evening. The constellation Pegasus is low in the eastern part of the sky and the Big Dipper to locate Polaris is fairly high in the sky to the north. When the student steps out for another break four hours later, how has the location of Pegasus changed?

Answer 1

Pegasus will have moved approximately 60 degrees westward in the sky after four hours due to Earth's rotation, as all non-circumpolar constellations shift westward over time.

Step-by-step explanation:

When the student returns to observe Pegasus four hours later, the constellation's position in the sky will have changed due to Earth's rotation. Over four hours, the celestial sphere appears to rotate about 60 degrees (as Earth rotates 15 degrees per hour). This means that all non-circumpolar constellations, including Pegasus, will have shifted westward in the sky. Pegasus will appear to have moved approximately 60 degrees westward from its previous position in the eastern sky. Celestial sphere rotation is the same apparent motion that causes the Sun to rise in the east and set in the west each day. While the Big Dipper is in the north circumpolar zone and maintains its position relative to Polaris, non-circumpolar constellations like Pegasus do not, and thus their positions change noticeably over several hours.

Answer 2

The location of Pegasus changed from low eastern part of the sky, by the time the student stepped out after four hours because it was seeking to achieve its normal location, which is the fourth quadrant of the Northern Hemisphere in the sky. Its latitude is between +90° and -60°.

Step-by-step explanation:

About Pegasus.

Pegasus is one of the largest constellation in the sky. Precisely, the seventh largest constellation in the sky. It occupies area of about 1121 Square Degrees.