Galaxy Collisions: Simulation vs Observations
14.05.2013

What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide.

From Alpha to Omega in Crete
29.06.2016

This beautiful telephoto composition spans light-years in a natural night skyscape from the island of Crete. Looking south, exposures both track the stars and record a fixed foreground in three merged panels that cover a 10x12 degree wide field of view. The May 15 waxing gibbous moonlight illuminates the church and mountainous terrain.

Perseid Night at Yosemite
18.08.2016

The 2016 Perseid meteor shower performed well on the night of August 11/12. The sky on that memorable evening was recorded from a perch overlooking Yosemite Valley, planet Earth, in this scene composed of 25 separate images selected from an all-night set of sequential exposures.

The Perseus Cluster Waves
4.05.2017

The cosmic swirl and slosh of giant waves in an enormous reservoir of glowing hot gas are traced in this enhanced X-ray image from the Chandra Observatory. The frame spans over 1 million light-years across the center of the nearby Perseus Galaxy Cluster, some 240 million light-years distant.

The Light, the Dark, and the Dusty
5.03.2020

This colorful skyscape spans about four full moons across nebula rich starfields along the plane of our Milky Way Galaxy in the royal northern constellation Cepheus. Near the edge of the region's massive...

Crepuscular Moon Rays over Denmark
27.07.2022

This moon made quite an entrance. Typically, a moonrise is quiet and serene. Taking a few minutes to fully peek above the horizon, Earth's largest orbital companion can remain relatively obscure until it rises high in the nighttime sky.

APOD: 2023 November 6 Б Red Aurora over Italy
6.11.2023

What was that red glow on the horizon last night? Aurora. Our unusually active Sun produced a surface explosion a few days ago that sent out a burst of electrons, protons, and more massive charged nuclei.

APOD: 2025 August 19 Б Giant Galaxies in Pavo
19.08.2025

Over 500,000 light years across, NGC 6872 (bottom left) is a truly enormous barred spiral galaxy. At least 5 times the size of our own large Milky Way, NGC 6872 is the largest known spiral galaxy.

Gamma Ray Bursts from the Unknown
23.11.1996

Gamma Ray Bursts (GRBs) pose one of the greatest mysteries of modern astronomy. About once a day, the gamma-ray sky lights up with a spectacular explosion. No one knows what causes these explosions or even how far away they are.

M74: The Perfect Spiral
24.05.2003

If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 30 million light-years away toward the constellation Pisces, NGC 628 or M74 presents a gorgeous face-on view to earthbound astronomers.