categories:Astronomy for beginners, Science | tags: Skip to content. Introducing the all-new Astronomy.com Forum! ... The semi-major axis is just a term for half of the longest length of the ellipse.

Chinese astronomers have employed NASA's Transiting Exoplanet Survey Satellite (TESS) to observe an eclipsing binary of the ...

Ganymede is Jupiter's third-closest major moon, orbiting the gas giant roughly once every seven days. It has a diameter of 3,270 miles (5,260 kilometers), according to NASA, making it the most ...