Asteroid 3753: Earth's Curious Companion
18.06.1997

Earth is not alone. It orbits the Sun with a small companion: Asteroid 3753. First discovered in 1986 and designated 1986 OT, this five kilometer rock was recently found to orbit the Sun while executing a strange dance with the Earth. A portion of the asteroid's complex orbit is shown above.

Infrared Ring Nebula
11.03.2005

The classic appearance of the popular Ring Nebula (aka M57) is understood to be due to perspective - our view from planet Earth looks down the center of a roughly barrel-shaped cloud of gas.

Journey to the Center of the Galaxy
22.04.2000

In Jules Verne's science fiction classic A Journey to the Center of the Earth, Professor Hardwigg and his fellow explorers encounter many strange and exciting wonders. What wonders lie at the center of our Galaxy?

Messier Craters in Stereo
11.12.2009

Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier, from his famous 18th century catalog. His name is also given to these two large and remarkable craters on the Moon.

Solar Flare in the Gamma ray Sky
15.03.2012

What shines in the gamma-ray sky? The answer is usually the most exotic and energetic of astrophysical environments, like active galaxies powered by supermassive black holes, or incredibly dense pulsars, the spinning remnants of exploded stars.

Galaxy Cluster Abell 370 and Beyond
6.05.2017

Some 4 billion light-years away, massive galaxy cluster Abell 370 only appears to be dominated by two giant elliptical galaxies and infested with faint arcs in this sharp Hubble Space Telescope snapshot. The fainter...

Messier Craters in Stereo
11.12.2020

Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier from his famous 18th century catalog. His name is also given to these two large and remarkable craters on the Moon.

Mercury and the Da Vinci Glow
10.07.2021

On July 8th early morning risers saw Mercury near an old Moon low on the eastern horizon. On that date bright planet, faint glow of lunar night side, and sunlit crescent were captured in this predawn skyscape from Tenerife's Teide National Park in the Canary Islands.

APOD: 2023 December 27 Б Rainbow Aurora over Icelandic Waterfall
27.12.2023

Yes, but can your aurora do this? First, yes, auroras can look like rainbows even though they are completely different phenomena. Auroras are caused by Sun-created particles being channeled into Earth's atmosphere by Earth's magnetic field, and create colors by exciting atoms at different heights.

Centaurus A: The Galaxy Deep Inside
4.12.1998

Deep inside Centaurus A, the closest active galaxy to Earth, lies ... another galaxy! Cen A is a giant elliptical galaxy a mere 10 million light-years distant with a central jumble of stars, dust, and gas that probably hides a massive black hole.