Distance

Measuring distances in astronomy is difficult but crucial. We need to know how far away objects are to look at the differences between them. Two objects can look different but be very similar, with one further away than the other. This can make them challenging to study.

An image of the night sky showing the constellation Orion, with the Orion Belt stars circled in blue for emphasis — Orion's belt

Measurement

In astronomy, measuring helps us learn the size, distance, and brightness of things in space.

Without these measurements, it would be hard to compare stars, planets, and galaxies.

Illustration with the title 'Measurement' showing various tools and symbols associated with measuring, including a ruler, protractor, balance scale, telescope, and electronic measuring device, set against a starry background with a galaxy image

What is a light year?

Read more about What is a light year?

Hunt the Asteroids

How do we find asteroids?

Read more about Hunt the Asteroids

Distances in Space

Distances to objects in space are very, very large. The nearest star (excluding the Sun), Alpha Centauri, is 41.23 trillion km, or 41,320,000,000,000 km!!

Read more about Distances in Space

Investigate the Size of a Galaxy

Have you ever wondered how big a galaxy is? They contain millions to billions of stars but what does that really mean for size?

Reading about sizes in a book is one thing, but what if you could make an observation of a galaxy and then measure its size?

Read more about Investigate the Size of a Galaxy

Investigate the Size of a Planet

Have you ever wondered how big each of the planets is? Bigger or smaller than the Earth?

Read more about Investigate the Size of a Planet

Measure a Day on Jupiter

You may know that the Earth takes 24 hours to rotate around its axis, but did you know other planets rotate as well? However, they do not all spin at the same rate.