# Angles in Astronomy

Angles are used a lot in astronomy. We can measure both the size of an object in the sky and mark its position by using angles.

However, sometimes the angles are very small - much less than a degree. Therefore, astronomers often use things called **arcminutes** and **arcseconds**.

• there are 360 degrees in a circle.

• an arcminute is 1/60^{th} of a degree.

• an arcsecond is 1/60^{th} of an arcminute.

Therefore, there are :

360 degrees × 60 arcminutes × 60 arcseconds = 1,296,000 arcseconds in a circle

That means that a five-pence coin would seem to be 1 arcsecond across when it was **3 kilometres away**! (This is the distance to Liverpool Cathedral in the picture).

Our Barnard's Star workshop allows students to apply their understanding of measuring angles to calculate the distance to a star