Aurora Over Clouds
2.04.2001

Aurorae usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact air molecules high in the Earth's atmosphere. An oxygen molecule, for example, will glow in a green light when reacquiring an electron lost during a collision with a solar particle.

APOD: 2023 March 7 Б Deep Field: The Large Magellanic Cloud
7.03.2023

Is this a spiral galaxy? No. Actually, it is the Large Magellanic Cloud (LMC), the largest satellite galaxy of our own Milky Way Galaxy. The LMC is classified as a dwarf irregular galaxy because of its normally chaotic appearance. In this deep and wide exposure, however, the full extent of the LMC becomes visible.

N11: Star Clouds of the LMC
11.02.2013

Massive stars, abrasive winds, mountains of dust, and energetic light sculpt one of the largest and most picturesque regions of star formation in the Local Group of Galaxies. Known as N11, the region...

NGC 6823: Cloud Sculpting Star Cluster
8.10.2014

Star cluster NGC 6823 is slowly turning gas clouds into stars. The center of the open cluster, visible on the upper right, formed only about two million years ago and is dominated in brightness by a host of bright young blue stars.

Asperitas Clouds Over New Zealand
19.08.2018

What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Formally recognized as a distinct cloud type only last year, Asperitas clouds can be stunning in appearance, unusual in occurrence, and are relatively unstudied.

Cap Cloud over the Sierra Nevadas
26.11.2013

One might say this was a bell weather day for the Sierra Nevada mountains. In January, just as the Sun was setting above the district of AlbayzМn in Grenada, Spain, a huge cloud appeared as a bell capping the Veleta peak.

Clouds Around Galaxy Andromeda
24.10.2022

What are those red clouds surrounding the Andromeda galaxy? This galaxy, M31, is often imaged by planet Earth-based astronomers. As the nearest large spiral galaxy, it is a familiar sight with dark dust lanes, bright yellowish core, and spiral arms traced by clouds of bright blue stars.

A Heart Shaped Lenticular Cloud
14.02.2016

Can a cloud love a mountain? Perhaps not, but on a Valentine's Day like today, one might be prone to seeing heart-shaped symbols where they don't actually exist. A fleeting pareidolia, the featured heart was really a lenticular cloud that appeared one morning last July above Mount Cook National Park in New Zealand.

Molecular Cloud Barnard 163
21.03.2007

It may look to some like a duck, but it lays stars instead of eggs. In the center of the above image lies Barnard 163, a nebula of molecular gas and dust so thick that visible light can't shine through it.

APOD: 2024 June 11 Б Colorful Stars and Clouds near Rho Ophiuchi
11.06.2024

Why is the sky near Antares and Rho Ophiuchi so colorful, yet dusty? The colors result from a mixture of objects and processes. Fine dust -- illuminated by starlight -- produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark.