The Matter of Galaxy Clusters
24.10.2001

Situated over 2,000,000,000 (two billion) light-years from Earth, galaxies in cluster Abell 2390 (top) and MS2137.3-2353 (bottom) are seen in the right hand panels above, false-color images from the Hubble Space Telescope. Corresponding panels on the left reveal each cluster's x-ray appearance in images from the Chandra X-ray Observatory.

The Magellanic Stream
24.01.2010

Spanning the sky toward the majestic Clouds of Magellan is an unusual stream of gas: the Magellanic Stream. The origin of this gas remains unknown but likely hold a clue to origin and fate of our Milky Way's most famous satellite galaxies: the LMC and the SMC.

A Cygnus Star Field
28.07.2004

In the constellation of the swan near the nebula of the pelican lies the gas cloud of the butterfly surrounding a star known as the hen. That star, given the proper name Sadr, is visible to the unaided eye but found here as the brightest object on the upper left.

In the Heart of the Rosette Nebula
11.03.2014

In the heart of the Rosette Nebula lies a bright open cluster of stars that lights up the nebula. The stars of NGC 2244 formed from the surrounding gas only a few million years ago.

Sand Dunes Thawing on Mars
23.09.2019

What are these strange shapes on Mars? Defrosting sand dunes. As spring dawned on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured here in late May by ESA's ExoMars Trace Gas Orbiter, began to thaw.

APOD: 2024 April 22 Б Moon and Smoke Rings from Mt Etna
21.04.2024

Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings, the walls of the volcano slightly slow the outside of emitted smoke puffs, causing the inside gas to move faster.

APOD: 2025 October 21 Б IC 1805: The Heart Nebula
20.10.2025

What electrifies the Heart Nebula? First, the large emission nebula on the left, catalogued as IC 1805, looks somewhat like a human heart. The nebula glows brightly in red light emitted by its most prominent element, hydrogen, but this long-exposure image was also blended with light emitted by sulfur (yellow) and oxygen (blue).

The Boomerang Nebula in Polarized Light
14.09.2005

Why did the Boomerang Nebula form? The symmetric cloud dubbed the Boomerang appears to have been created by a high-speed wind of gas and dust blowing from an aging central star at speeds of nearly 600,000 kilometers per hour.

Blue Stars and Red Pillars
18.07.1997

Bright blue stars are still forming in the red pillars of the Eagle Nebula. Made famous by a picture from the Hubble Space Telescope in 1995, the Eagle Nebula shows the dramatic process of star formation. To the upper right of the nebula in the above picture lies the heart of the open cluster M16.

NGC 5643: Nearby Spiral Galaxy from Hubble
4.10.2020

What's happening at the center of spiral galaxy NGC 5643? A swirling disk of stars and gas, NGC 5643's appearance is dominated by blue spiral arms and brown dust, as shown in the featured image taken by the Hubble Space Telescope.