The Gegenschein Over Chile
14.01.2014

Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles.

Pleiades from Planet Earth
1.11.2025

The lovely Pleiades star cluster shines in Earth's night sky, a compact group of stars some 400 light-years distant toward the constellation Taurus and the Orion Arm of our Milky Way galaxy. Recognized since ancient times, the remarkable celestial gathering is visible to the unaided eye.

APOD: 2024 May 24 Б M78 from the Euclid Space Telescope
24.05.2024

Star formation can be messy. To help find out just how messy, ESA's new Sun-orbiting Euclid telescope recently captured the most detailed image ever of the bright star forming region M78. Near...

Geostationary Highway
20.02.2010

Put a satellite in a circular orbit about 42,000 kilometers from the center of the Earth (36,000 kilometers or so above the surface) and it will orbit once in 24 hours. Because that matches Earth's rotation period, it is known as a geosynchronous orbit.

The Fainting of Betelgeuse
2.01.2020

Begirt with many a blazing star, Orion the Hunter is one of the most recognizable constellations. In this night skyscape the Hunter's stars rise in the northern hemisphere's winter sky on December 30, 2019, tangled in bare trees near Newnan, Georgia, USA.

Star Trails in Northern Skies
1.12.1996

As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric arcs traced out by the stars in this time exposure of the night sky.

The Winter Hexagon
6.11.2002

Some of the brightest stars form a large and easily found pattern in the winter sky of Earth's northern hemisphere. Dubbed the Winter Hexagon, the stars involved can usually be identified even in the bright night skies of a big city.

Neutron Star Earth
16.06.1995

If the Earth could somehow be transformed to the ultra-high density of a neutron star , it might appear as it does in the above computer generated figure. Due to the very strong gravitational field, the neutron star distorts light from the background sky greatly. If you look closely, two

Constellation Construction
20.07.2006

This lovely twilight scene, recorded last April, finds a young crescent Moon low in the west at sunset. Above it, stars shine in the darkening sky but they too are soon to drop below the western horizon.

Alborz Mountains in Moonlight
3.02.2007

On January 25th, light from a first quarter Moon illuminated this dreamlike landscape looking across the rugged, snow-covered peaks of the Alborz Mountain Range in northern Iran. The stunning sky is filled with stars, including the yellow-tinged Betelgeuse at the shoulder of Orion.