Eayn
From Halopedia, the Halo wiki
Eayn was the Jackal homeworld and a satellite of the planet Chu'ot. It's primary moon is Y'Deio. The gravity is about .875 G's, making the inhabitants lighter on this planet then on earth. This is suprising, considering how fast Jackals move on Earth.
The atmosphere contains Nitrogen, Carbon Dioxide and Dioxide, similar to Earth.
The population of Eayn is 978 million.
References
[1] Halo 3 Beastiarium, pg. 8-9
