The Case of the Missing Supernova
13.04.1999

Would you notice a second Moon in the sky? About 700 years ago, light from a tremendous explosion reached Earth that should have appeared almost as bright as a full Moon. The bright spot should have lasted for weeks, yet no notation of such an occurrence has been found in historical records.

The Solar Spectrum
23.04.2006

It is still not known why the Sun's light is missing some colors. Shown above are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device.

X-Rays From Antennae Galaxies
18.08.2000

A bevy of black holes and neutron stars shine as bright, point-like sources against bubbles of million degree gas in this false-color x-ray image from the orbiting Chandra Observatory. The striking picture shows...

NGC 281
10.12.2008

Look through the cosmic cloud cataloged as NGC 281 and it's almost easy to miss stars of the open cluster IC 1590. But, formed within the nebula, that cluster's young, massive stars ultimately power the pervasive nebular glow.

Saturn in View
4.03.2009

Very good telescopic views of Saturn can be expected in the coming days as the ringed planet nears opposition on March 8th, its closest approach to Earth in 2009. Of course, opposition means opposite the Sun in planet Earth's sky - an arrangement that occurs almost yearly for Saturn.

PanSTARRS over Parkes
9.03.2013

Sweeping quickly through southern skies on March 5, Comet PanSTARRS (C/2011 L4) follows the Sun toward the western horizon in this twilight scene. In the foreground is Australia's CSIRO Parkes Radio Telescope, a 64 meter wide steerable dish that is no stranger to the space age exploration of comets.

Airglow Borealis
27.10.2018

The best known asterism in northern skies hangs over the Canadian Rockies in this mountain and night skyscape taken last week from Banff National Park. But most remarkable is the amazing greenish airglow. With...

The Orion Bullets
3.03.2019

Why are bullets of gas shooting out of the Orion Nebula? Nobody is yet sure. First discovered in 1983, each bullet is actually about the size of our Solar System, and moving at about 400 km/sec from a central source dubbed IRc2.

APOD: 2025 December 7 Б The Sun and Its Missing Colors
7.12.2025

It is still not known why the Sun's light is missing some colors. Here are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device.

M51: The Whirlpool Galaxy in Dust and Stars
19.02.2006

The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky.