Until around 30 years ago, we only knew of the eight (or maybe nine !) planets around our own Sun. However, it was long thought that other stars would also contain their own planetary systems. This field of study has developed from the first discoveries back in the early 1990s until today where we know of thousands of these exoplanets.
To understand more about these exoplanets, this activity takes you to a website called The Extrasolar Planets Encyclopaedia and explains how you can create graphs (or plots) using data from up to 4000 of these objects (see Figure 1).