COROT will use its telescope to monitor closely the changes in a star’s brightness that comes from a planet crossing in front of it.

While it is looking at a star, COROT will also be able to detect ‘starquakes’, acoustical waves generated deep inside a star that send ripples across a star’s surface, altering its brightness. The exact nature of the ripples allows astronomers to calculate the star's precise mass, age and chemical composition.

Credits: CNES 2006 - D. Ducros

From Earth, both Mercury and Venus occasionally pass across the front of the Sun. When they do, they look like tiny black dots passing across the bright surface.

Such transits block a tiny fraction of the light that COROT is able to detect.

Credits: CNES

This technique is known as asteroseismology and ESA’s Solar and Heliospheric Observatory (SOHO) has been taking similar observations of the Sun for years.

Credits: CNES