Cas A Supernova Remnant in X Rays
24.08.2002

The complex shell of a star seen to explode 300 years ago is helping astronomers to understand how that star exploded. This Chandra Observatory image of supernova remnant Cassiopeia A (Cas A) shows unprecedented detail in three x-ray colors.

Zodiacal Light Over Laguna Verde
29.10.2009

An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.

The Small Cloud of Magellan
5.01.2021

What is the Small Magellanic Cloud? It has turned out to be a galaxy. People who have wondered about this little fuzzy patch in the southern sky included Portuguese navigator Ferdinand Magellan...

Earthset from Orion
23.11.2022

Eight billion people are about to disappear in this snapshot from space. Taken on November 21, the sixth day of the Artemis 1 mission, their home world is setting behind the Moon's bright edge as viewed by an external camera on the outbound Orion spacecraft.

Home from Above
15.11.2010

There's no place like home. Peering out of the windows of the International Space Station (ISS), astronaut Tracy Caldwell Dyson takes in the planet on which we were all born, and to which she would soon return.

Zodiacal Light and the False Dawn
15.09.2002

An unusual triangle of light will be particularly bright near the eastern horizon before sunrise during the next two months for observers in Earth's northern hemisphere. Once considered a false dawn, this triangle of light is actually Zodiacal Light, light reflected from interplanetary dust particles.

The Case of the Missing Supernova
13.04.1999

Would you notice a second Moon in the sky? About 700 years ago, light from a tremendous explosion reached Earth that should have appeared almost as bright as a full Moon. The bright spot should have lasted for weeks, yet no notation of such an occurrence has been found in historical records.

Moonrise Over Turkey
16.06.2009

Is the Moon larger when near the horizon? No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky. Oddly, the cause or causes for the common Moon Illusion are still being debated.

APOD: 2023 April 25 Б Northern Lights over Southern Europe
25.04.2023

Did you see an aurora over the past two nights? Many people who don't live in Earth's far north did. Reports of aurora came in not only from northern locales in the USA as Alaska, but as far south as Texas and Arizona. A huge auroral oval extended over Europe and Asia, too.

APOD: 2025 June 2 Б Veil Nebula: Wisps of an Ancient Supernova
2.06.2025

Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova, leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history.