One summer night in 1877, American astronomer Asaph Hall was looking through his telescope in Washington, D.C. Mars was at its closest point to Earth in its orbit, and Hall had one question on his ...

When Earth is opposite Mars from the sun, it will appear full because you’re looking directly on the daylit side. But ...

Former NASA astronaut and moon-walker Buzz Aldrin told Business Insider about his vision for a shuttling system to Mars. He said there's no reason to build a permanent human colony on the moon, but ...

The 6%-lit waxing crescent moon will be visible roughly 5 degrees above the horizon as the sun sets on Oct. 23, with Mercury ...