APOD: 2023 October 25 Б Gone in 60 Seconds: A Green Flash Sunset
25.10.2023

In 60 seconds, this setting Sun will turn green. Actually, the top of the Sun already appears not only green, but wavey -- along with all of its edges. The Sun itself is unchanged -- both effects are caused by looking along hot and cold layers in Earth's atmosphere.

APOD: 2024 March 4 Б Light Pillars Over Inner Mongolia
4.03.2024

What's happening across that field? Pictured here are not auroras but nearby light pillars, a phenomenon typically much closer. In most places on Earth, a lucky viewer can see a Sun pillar, a column of light appearing to extend up from the Sun caused by flat fluttering ice-crystals reflecting sunlight from the upper atmosphere.

APOD: 2026 March 23 Б Light Pillars and Orion over Mohe
23.03.2026

What's happening at the end of that street? Pictured here are not auroras but light pillars, a phenomenon typically much closer. In most places on Earth, a lucky viewer...

A Gallery of Gravitational Mirages
1.06.1999

The deeper you peer into the universe, the harder it is to see straight. The reason is that distant galaxies act as gravitational lenses, deflecting light that passes nearby. These deflections result in the distortion of background sources, and in some cases the creation of multiple images.

Anticrepuscular Rays Over Colorado
28.11.2010

What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds.

The Terraced Night
6.02.2014

Long after sunset on January 25 an unusually intense red airglow floods this south-looking skyscape. The scene was recorded with a long exposure using a digital camera over Yunnan Province in southwest China. At best faintly visible to the eye, the lingering airglow is due to chemiluminescence, the production of light through chemical excitation.

Sprite Lightning in HD
8.10.2019

This phenomenon occurs in the sky over our heads, not the sea. It is a type of lightning known as red sprite, and rarely has it ever been photographed in this detail. Even though sprites have been recorded for over 30 years, their root cause remains unknown. Some thunderstorms have them, but most don't.

The Veins of Heaven
19.06.2020

Transfusing sunlight through a darkened sky, this beautiful display of noctilucent clouds was captured earlier this week, reflected in calm waters from Nykobing Mors, Denmark. From the edge of space, about 80 kilometers above...

NGC 6357: The Lobster Nebula
28.10.2020

Why is the Lobster Nebula forming some of the most massive stars known? No one is yet sure. Cataloged as NGC 6357, the Lobster Nebula houses the open star cluster Pismis 24 near its center -- a home to unusually bright and massive stars.

Moon Near the Edge
12.04.2025

Most of us watch the Moon at night. But the Moon spends nearly as many daylight hours above our horizon, though in bright daytime skies the lunar disk looks pale and can be a little harder to see.