The original version of this story appeared in Quanta Magazine. In October, a Falcon Heavy rocket is scheduled to launch from Cape Canaveral in Florida, carrying NASA’s Europa Clipper mission. The $5 ...

HELSINKI — China has sent several small spacecraft into specialized lunar and cislunar orbits to test communications, navigation and orbital dynamics for planned Earth-moon infrastructure. China’s DRO ...

Many maps of the solar system make it look as though everything in space moves in perfect, concentric circles. Planets orbit the sun, and moons orbit the planets. So that must be the case for ...

Astronomers have spotted a quasi-moon near Earth — and the small space rock has likely been hanging out near our planet unseen by telescopes for about 60 years, according to new research. The newly ...

For the inner four planets in this solar system, each planet orbits the sun three times for every two orbits of the planet immediately to its outside. For the fourth, fifth and sixth planets, they ...