What do the symbols °, , and ” mean when measuring angles?
Angular measure on the sky is a useful way of describing how big an object looks or how far apart two objects may appear. For example, the width of the Moon in the sky subtends about 1/2 degree (°) as seen by the eye (An aspirin tablet held at arm’s length covers about the same width!). The height of the north star above the northern horizon is between 45 and 49 degrees for Montana observers. A degree can be divided into smaller increments, and comes into play when telescope viewing since the field of view is often covering only a fraction of a degree. Think in terms of time: 60 minutes of arc (60′) = one degree (1°) 60 seconds of arc (60″) = 1 minute of arc (1′) These units can be used in describing Declination, but do not confuse the “hours” and “minutes” of Right Ascension with this. Right Ascension really IS related to time — specifically, the rotation of the Earth. If you need to know the angles when reading maps, the relationship for Right Ascension is: 1 Hour of Right Ascension
