In the bigger picture, “down” could be defined as being below the plane of the solar system, which is known as the ecliptic.

Four days after launching on its third-ever mission, China's mysterious Shenlong robotic space plane has apparently deployed 6 unknown objects in orbit. Some of them appear to be emitting signals.

A collision would occur in just 2.8 days if all satellites lost their ability to dodge each other, highlighting how crowded Earth’s orbit is becoming. In the past seven years, the number of satellites ...