When Z is for Mars
14.04.2023

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: 2023 December 10 Б Big Dipper over Pyramid Mountain
9.12.2023

When did you first learn to identify this group of stars? Although they are familiar to many people around the world, different cultures have associated this asterism with different icons and folklore. Known...

APOD: 2025 February 18 Б Thors Helmet versus the Seagull
17.02.2025

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 October 1 Б NGC 6960: The Witchs Broom Nebula
30.09.2025

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.

The Milky Way Over Mauna Kea
26.01.2009

Have you ever seen the band of our Milky Way Galaxy? In a clear sky from a dark location at the right time, a faint band of light becomes visible across the sky. Soon after your eyes become dark adapted, you might spot the band for the first time. It may then become obvious.

Galaxies Beyond the Heart: Maffei 1 and 2
8.03.2010

The two galaxies on the far left were unknown until 1968. Although they would have appeared as two of the brighter galaxies on the night sky, the opaque dust of the central band of our Milky Way Galaxy had obscured them from being seen in visible light.

Geminids from Gemini
15.11.2021

Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Gemini. That is why the major meteor shower in December is known as the Geminids -- because shower meteors all appear to come from a radiant toward Gemini.

The X-Ray Sky
1.01.1996

What if you could see X-rays? If you could, the night sky would be a strange and unfamiliar place. X-rays are about 1,000 times more energetic than visible light photons and are produced in violent and high temperature astrophysical environments.

Perseid Below
17.08.2011

Denizens of planet Earth watched this year's Perseid meteor shower by looking up into the moonlit night sky. But this remarkable view captured by astronaut Ron Garan looks down on a Perseid meteor.

A Candidate for the Biggest Boom Yet Seen
25.01.2016

It is a candidate for the brightest and most powerful explosion ever seen -- what is it? The flaring spot of light was found by the All Sky Automated Survey for Supernovae (ASASSN) in June of last year and labelled ASASSN-15lh.