James Van Allen discovered the two Earth-circling radiation belts that bear his name in 1958. The discovery, based on data from Explorer 1 (the first U.S. satellite), Explorer 3, and Pioneer 3, was ...

In August 1960, NASA launched its first communications satellite, Echo 1. Fifty years later, NASA has achieved another first by placing the ARTEMIS-P1 spacecraft into a unique orbit behind the moon, ...

As lunar exploration intensifies, the cislunar space is experiencing increasing congestion. Traditional two-body Keplerian elements, which have long been the standard for Earth-orbiting objects, prove ...

First, authors present the dynamical models and pursuit-evasion orbits used in this paper In this paper, the Earth-Moon rotating frame (EMR) and the circular restricted three body problem (CR3BP) is ...

The libration of the moon, and changes in its actual size as seen from Earth, are beautifully illustrated in the movie linked to at the bottom of this Astronomy Picture of the Day page. (Note: Wait ...

The Moon takes the same time (27.3 days) to rotate once on its axis as it takes to orbit the Earth. This is called synchronous rotation. Does this mean we always see the same face of the Moon, and ...

In August 1960, NASA launched its first communications satellite, Echo 1. Fifty years later, NASA has achieved another first by placing the ARTEMIS-P1 spacecraft into a unique orbit behind the moon, ...