A star with RA = 4^h is in your meridian at a certain time. Which of the following stars will be on your meridian 2.5 hours from now?

Question

Quizplus · Accepted Answer

The Earth rotates 15 degrees per hour, so in 2.5 hours, it will have rotated 37.5 degrees. Since Right Ascension (RA) is measured in hours, minutes, and seconds, with 24 hours corresponding to 360 degrees, 2.5 hours of RA corresponds to 37.5 degrees of rotation. Therefore, a star with RA = 4h will be followed 2.5 hours later by a star with RA = 6h 30m, which is option A.

A Star with RA = 4h Is in Your Meridian

A Star with RA = 4^h Is in Your Meridian