Andromeda in a Single Shot
25.06.2021

How far can you see? The Andromeda Galaxy, 2.5 million light years away, is the most distant object easily seen by the unaided eye. Other denizens of the night sky, like stars, clusters, and nebulae, are typically hundreds to thousands of light-years distant.

Circling a Black Hole at its Photon Sphere
2.07.2013

What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon.

M82: An Irregular Galaxy
28.07.1995

Not all galaxies have spiral structure like our Milky Way. Many have smooth elliptical shapes, but also many have irregular shapes such as the bright sky object M82, the 82nd object on Messier's list.

Calm, Crescent Moon, and Venus
21.05.2010

Last weekend, the Moon and Venus formed a beautiful close pair in the west after sunset, a scene enjoyed by skygazers all over the world. In this lovely view of the conjunction from Sweden, a calm lake Vallentuna lies in the foreground with sunset colors still fading behind the treeline on the far shore.

Quadrantids: Meteors in Perspective
26.01.1996

Meteor showers are caused by streams of solid particles, dust size and larger, moving as a group through space. In many cases, the orbits of these meteor streams can be identified with the dust tails of comets.

Star Trails of the North and South
12.02.2020

What divides the north from the south? It all has to do with the spin of the Earth. On Earth's surface, the equator is the dividing line, but on Earth's sky, the dividing line is the Celestial Equator -- the equator's projection onto the sky.

11 Hour Star Trails
15.09.2006

Fix your camera to a tripod, lock the shutter open, and you can make an image of star trails - graceful concentric arcs traced by the stars as planet Earth rotates on its axis. Of course, the length of the star trails will depend on the exposure time.

Meteor Over Crater Lake
25.04.2012

Did you see it? One of the more common questions during a meteor shower occurs because the time it takes for a meteor to flash is typically less than the time it takes for a head to turn.

Orion: Belt, Flame, and Horsehead
4.06.2017

What surrounds the famous belt stars of Orion? A deep exposure shows everything from dark nebula to star clusters, all embedded in an extended patch of gaseous wisps in the greater Orion Molecular Cloud Complex.

APOD: 2025 September 25 Б Saturn Opposite the Sun
25.09.2025

This year Saturn was at opposition on September 21, opposite the Sun in planet Earth's sky. At its closest to Earth, Saturn was also at its brightest of the year, rising as the Sun set and shining above the horizon all night long among the fainter stars of the constellation Pisces.