APOD: 2023 March 8 Б Artificial Night Sky Brightness
8.03.2023

Where have all the dim stars gone? From many places on the Earth including major cities, the night sky has been reduced from a fascinating display of thousands of stars to a diffuse glow through which only a few stars are visible.

Gamma Ray Quasar
26.12.1998

The bright object in the center of the false color image above is quasar 3C279 viewed in gamma-rays, photons with more than 40 million times the energy of visible light. Like all quasars, 3C279 is a nondescript, faint, star-like object in the visible sky.

The Cosmic Infrared Background
6.02.2002

What cosmic wallpaper is on the sky? The answer depends on the type of light considered, and for some wavelengths, all the cluttering material in the foreground makes it still unknown. Recently, however...

Meteor and Moonbow over Wallaman Falls
12.11.2012

Which feature takes your breath away first in this encompassing panorama of land and sky? The competition is strong with a waterfall, meteor, starfield, and even a moonbow all vying for attention. It is interesting to first note, though, what can't be seen -- a rising moon on the other side of the camera.

Retrograde Mars
13.06.2010

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

Retrograde Mars
11.05.2008

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

Retrograde Mars
27.10.2014

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

Retrograde Mars
16.12.2003

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

The Annotated Galactic Center
27.09.2019

The center of our Milky Way galaxy can be found some 26,000 light-years away toward the constellation Sagittarius. Even on a dark night, you can't really see it though. Gaze in that direction, and your sight-line is quickly obscured by intervening interstellar dust.

Corona from Svalbard
31.03.2015

During a total solar eclipse, the Sun's extensive outer atmosphere, or corona, is an inspirational sight. Streamers and shimmering features that engage the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a single photograph.