Where Is Star Plus?

A bright star is rising at midnight from the east where would the star be on the celestial sphere at 6am?

• Answer:

  6 AM is 6 hours past midnight -- 6 hours equals one quarter turn of the earth (because that's 1/4 of 24 hours). A quarter turn is 90 degrees. So at 6 AM the start will be in a position 90 degrees away from where it was at midnight. That could mean it's directly overhead (if you're watching from the equator); or somewhat north or south of directly overhead (if you're watching from some different latitude). In any case it's on the "meridian," and imaginary half-circle stretching over your head and extending from the north horizon to the south horizon. > "Where would the star be...at midnight after three months?" In addition to making a complete eastward turn in about 24 hours, the celestial sphere bumps westward by about an additional 1 degree every day (making a full 360-degree turn in a year). That means in 3 months it will have made a quarter turn (when viewed at the same time of night both times). So the star again will be 90 degrees away from where it was on midnight 3 months ago.