Detection of an exoplanet by star movement

Subject :

Exoplanets are not bright enough to be seen, but they can be massive enough to cause the stars they orbit to move. The first goal of this activity is to grasp the concept of centre of gravity of two objects. Then, by observing the movement of stars, guess if their movement can reveal the presence of planets?

Level : Primary school
Duration : about 1 hour

Objectives :

• Approach the notion of centre of gravity
• Detect the presence of planets in star fields.

Materials required:

• Wooden or bamboo stick (50 cm)
• String
• Packets weighing 1kg, 500g, 250g, 100g (pasta, sugar, etc.) two of each

Subject, Annexe et correction :

• Subject, annexe and correction

Authors : Françoise Roques, Mathieu Hirtzig (UFE, Observatoire de Paris), Yaël Nazé (université de Lièges).