Orbital Mechanics

Skywatching

Venus often appears as the brightest planet in Earth’s sky and tonight it stands out because of where it lies along its orbit and how its illuminated fraction and distance com...

Physics & Space

Satellites stay in space because they are in freefall around Earth, moving sideways fast enough that as they fall their curved path matches Earth’s curve. Gravity pulls them i...

space

Travel time to the Moon depends on the spacecraft, trajectory, and mission profile. The fastest human transit was Apollo 8’s commanded module traveling from low-Earth parking...

space-explainer

Travel time to Earth’s nearest neighbor depends on mission profile, spacecraft speed, and orbital mechanics rather than a single fixed number. On average, crewed and robotic m...