- Spica (Wikipedia)
Spica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Analysis of its parallax shows that it is located 250±10 light-years from the Sun. It is a spectroscopic binary star and rotating ellipsoidal variable; a system whose two stars are so close together they are egg-shaped rather than spherical, and can only be separated by their spectra. The primary is a blue giant and a variable star of the Beta Cephei type.
- Earth–Moon system (Wikipedia)
The Earth and the Moon form the Earth-Moon satellite system with a shared center of mass, or barycenter. This barycenter stays located at all times 1,700 km (1,100 mi) (about a quarter of Earth’s radius) beneath the Earth’s surface, making the Moon seemingly orbit the Earth.