A Blue Banded Blood Moon
1.12.2021

What causes a blue band to cross the Moon during a lunar eclipse? The blue band is real but usually quite hard to see. The featured HDR image of last week's lunar eclipse, however -- taken from Yancheng, China -- has been digitally processed to equalize the Moon's brightness and exaggerate the colors.

The Cartwheel Galaxy from Webb
24.08.2022

To some, it looks like a wheel of a cart. In fact, because of its outward appearance, the presence of a central galaxy, and its connection with what looks like the spokes of a wheel, the galaxy on the right is known as the Cartwheel Galaxy.

When Z is for Mars
15.04.2023

A composite of images captured about a week apart from mid August 2022 through late March 2023, this series traces the retrograde motion of ruddy-colored Mars. Progressing from lower right to upper left Mars...

APOD: 2025 February 18 Б Thors Helmet versus the Seagull
18.02.2025

Seen as a seagull and a duck, these nebulae are not the only cosmic clouds to evoke images of flight. But both are winging their way across this broad celestial landscape, spanning almost 7 degrees across planet Earth's night sky toward the constellation of the Big Dog (Canis Major).

APOD: 2025 September 11 Б The Umbra of Earth
11.09.2025

The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse.

APOD: 2025 October 1 Б NGC 6960: The Witchs Broom Nebula
1.10.2025

Ten thousand years ago, before the dawn of recorded human history, a new light would suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant.

SN 1006: Pieces of the Cosmic Ray Puzzle
2.12.2000

Research balloon flights conducted in 1912 by Austrian physicist Victor Hess revealed that the Earth was constantly bombarded by high energy radiation from space - which came to be called "Cosmic Rays". What are Cosmic Rays and where do they come from?

Titania's Trenches
11.01.1997

British astronomer Sir William Herschel discovered Titania and Oberon in 1787, 210 years ago today. He wasn't reading Shakespeare's A Midsummer Night's Dream though, he was making the first telescopic observations of moons of the planet Uranus (a planet which he himself discovered in 1781).

Mars Then and Now
12.11.2003

Does Mars have canals? A hot debate topic of the late 1800s, several prominent astronomers including Percival Lowell not only claimed to see an extensive system of long straight canals on Mars, but used them to indicate that intelligent life exists there.

The Comets Of SOHO
25.02.2000

After four years of successful sun-gazing, the space-based SOlar and Heliospheric Observatory (SOHO) has also become the most successful comet-hunter in history, racking up 102 new comets. Above are examples of SOHO's comet discoveries imaged by LASCO, an on-board coronagraph.