APOD: 2023 September 17 Б Moon Mountains Magnified during Ring of Fire Eclipse
16.09.2023

What are those dark streaks in this composite image of a solar eclipse? They are reversed shadows of mountains at the edge of the Moon. The center image, captured from Xiamen, China, has the Moon's center directly in front of the Sun's center.

X-Rays From The Perseus Cluster Core
15.06.2000

The Perseus Cluster of thousands of galaxies, 320 million light-years distant, is one of the most massive objects in the Universe. At its core lies the giant cannibal galaxy Perseus A (NGC 1275), accreting matter as gas and galaxies fall into it.

Gamma Ray Bursts from the Unknown
27.08.1995

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.

Cometary Knots in the Helix Nebula
16.04.1996

Four hundred fifty light-years from Earth, the wind from a dying, sun-like star produced a planetary nebula popularly known as the Helix. While exploring the Helix's gaseous envelope with the Hubble Space Telescope (HST), astronomers discovered indications of 1,000s of striking "cometary knots" like those shown above.

Blue Stragglers in NGC 6397
8.08.2003

In our neck of the Galaxy stars are too far apart to be in danger of colliding, but in the dense cores of globular star clusters star collisions may be relatively common. In fact...

What is Hanny's Voorwerp?
25.06.2008

What is that green thing? A volunteer sky enthusiast surfing through online Galaxy Zoo images has discovered something really strange. The mystery object is unusually green, not of any clear galaxy type, and situated below relatively normal looking spiral galaxy IC 2497.

Namibian Nights
4.02.2013

Namibia has some of the darkest nights visible from any continent. It is therefore home to some of the more spectacular skyscapes, a few of which have been captured in the above time-lapse video.

A Volcanic Great Conjunction
19.12.2020

Where can I see the Great Conjunction? Near where the Sun just set. Directionally, this close passing of Jupiter and Saturn will be toward the southwest. Since the planetary pair...

APOD: 2024 October 20 Б Dark Matter in a Simulated Universe
19.10.2024

Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters...

NGC 1850: Not Found in the Milky Way
12.07.2001

A mere 168,000 light-years distant, this large, lovely cluster of stars, NGC 1850, is located near the outskirts of the central bar structure in our neighboring galaxy, the Large Magellanic Cloud. A first...