Most comets are only visible through telescopes. Why do some become spectacular naked-eye sights?

Work, exercise and 16 sunrises a day: what everyday life looks like 400 km above Earth.

This year the Perseids peak close to new Moon, which promises excellent viewing conditions.

The "Blue Marble", taken by the Apollo 17 crew in 1972, is one of the most reproduced images in history.

What is a black hole, can we see one, and could one swallow Earth? Short answers to common questions.

During their flight around the Moon, the Artemis II astronauts photographed Earth setting behind the lunar horizon.

The James Webb Space Telescope observes infrared light, which our eyes cannot see. Here is why that matters.

In 2006 astronomers decided what a planet is, and Pluto did not make the cut. Twenty years later, the debate is still alive.

It sounds like a unit of time, but a light-year measures distance. Here is how far it really is.