V838 Light Echo: The Movie
17.06.2014

What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon suddenly became one of the brightest stars in the entire Milky Way Galaxy. Then, just a few months later, it faded.

APOD: 2026 May 13 Б NGC 188: Old Cluster in the New General Catalog
12.05.2026

The New General Catalog of star clusters and nebulae really isn't so new. In fact, it was published in 1888 - an effort by J. L. E. Dreyer to consolidate the work of astronomers William, Caroline, and John Herschel along with others into a useful single, complete catalog of astronomical discoveries and measurements.

The Milky Way Over Ontario
29.07.2008

Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case earlier this month over Ontario, Canada, when part of a spectacular sky also became visible in a reflection off a lake.

Spin up of a Supermassive Black Hole
12.03.2013

How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown.

Massive Stars in NGC 6357
4.02.2016

Massive stars lie within NGC 6357, an expansive emission nebula complex some 6,500 light-years away toward the tail of the constellation Scorpius. In fact, positioned near center in this ground-based close-up...

Supernova Remnant Cassiopeia A
16.01.2025

Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After only a few million years for the most massive stars, the enriched material is blasted back into interstellar space where star formation can begin anew.

Supernova Survivor
10.09.2005

Beginning with a full view of beautiful spiral galaxy M81, follow the insets (left, bottom, then right) to zoom in on a real survivor. Seen at the center of the final field on the right is a star identified as the survivor of a cosmic cataclysm -- the supernova explosion of its companion star.

A Protected Night Sky Over Flagstaff
16.04.2008

This sky is protected. Yesterday marked the 50 year anniversary of the first lighting ordinance ever enacted, which restricted searchlight advertisements from sweeping the night skies above Flagstaff, Arizona, USA. Flagstaff now enjoys...

Powers of Ten
31.01.2011

How different does the universe look on small, medium, and large scales? The most famous short science film of its generation gives breathtaking comparisons. That film, Powers of Ten, originally created in the 1960s, has now been officially posted to YouTube and embedded above.

M46 and M47: Star Clusters Young and Old
3.04.2012

Many stars form in clusters. Galactic or open star clusters are relatively young swarms of bright stars born together near the plane of our Milky Way Galaxy. Separated by about a degree...