Airglow, Gegenschein, and Milky Way
20.04.2013

As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds.

Orions Belt Region in Gas and Dust
11.01.2022

You may have seen Orion's belt before -- but not like this. The three bright stars across this image are, from left to right, Mintaka, Alnilam, and Alnitak: the iconic belt stars of Orion.

The Colorful Clouds of Rho Ophiuchi
12.03.1996

The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light.

La Silla Star Trails North and South
2.02.2012

Fix your camera to a tripod and you can record graceful trails traced by the stars as planet Earth rotates on its axis. If the tripod is set up at ESO's La Silla Observatory, high in the Atacama desert of Chile, your star trails would look something like this.

Geminid Meteors over Chile
8.12.2019

Are meteors streaming out from a point in the sky? Yes, in a way. When the Earth crosses a stream of Sun-orbiting meteors, these meteors appear to come from the direction of the stream -- with the directional point called the radiant.

APOD: 2023 June 29 Б A Message from the Gravitational Universe
29.06.2023

Monitoring 68 pulsars with very large radio telescopes, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has uncovered evidence for the gravitational wave (GW) background by carefully measuring slight shifts in the arrival times of pulses. These shifts are correlated between different pulsars in a way that indicates that they are caused by GWs.

Andromeda Nebula: Var!
6.04.1996

In the 1920s, using photographic plates made with the Mt. Wilson Observatory's 100 inch telescope, Edwin Hubble determined the distance to the Andromeda Nebula - decisively demonstrating the existence of other galaxies far beyond the Milky Way.

M74: The Perfect Spiral
6.04.2011

If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 32 million light-years away toward the constellation Pisces, M74 presents a gorgeous face-on view.

Hale-Bopp on Schedule
25.07.1996

Late March and early April of 1996 marked a banner season for viewing the spectacular naked-eye comet Hyakutake. The spring of 1997 could well offer a similar cometary wonder, Comet Hale-Bopp. Discovered last year while approaching the inner solar sytem Hale-Bopp has been eagerly watched for signs that it will indeed brighten spectacularly.

Peculiar Arp 295
10.10.2003

A spectacular bridge of stars and gas stretches for nearly 250,000 light-years and joins this famous peculiar pair of galaxies cataloged as Arp 295. The cosmic bridge between the galaxies and the long...