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First extrasolar planet discovered orbiting a main-sequence star

First extrasolar planet discovered orbiting a main-sequence star
Who
Dimidium
What
First
Where
Not Applicable
When
1995

51 Pegasi b, discovered in 1995, orbits 51 Pegasi, a G5V main sequence star similar to the Sun. 51 Pegasi is around 50.9 light years away in the constellation of Pegasus. The planet 51 Pegasi b was discovered using spectroscopy, which showed slight changes in velocity of the star’s spectral lines, owing to the gravitational effects of the planet.

51 Pegasi b is a type of planet known as a "hot Jupiter". It orbits its star at a distance of just 7.8–7.9 million km and takes just four hours to complete an orbit.

Since its discovery, the International Astronomical Union has given 51 Pegasi b the official name of Dimidium.