51 Pegasi


Credit: The Royal Observatory Edinburgh

The first exo-planet ever discovered was found in 1995 orbiting the star 51 Pegasi shown in the image above.

The planet orbits the star every 4 days or so and it was discovered through the radial velocity  method (Doppler Shift)which detects tiny wobbles in the stars motion caused by the gravitational tug of the orbiting planet, which is too small to be seen visually.


The first exo-planet – Pegasi B, is thought to be a ‘hot Jupiter’ and was discovered by Swiss astronomers Michel Mayor and Didier Queloz using a telescope at the Observatoire de Haute-Provence in France.

Pegasi 51 is a Sun-like star (slightly larger and slightly older) and is located approximately 51 light years away in the constellation of Pegasus, see chart below.



The star has an apparent magnitude of 5.5 and is therefore just visible to the naked eye in good conditions.