Andromeda over Patagonia
25.11.2020

How far can you see? The Andromeda Galaxy at 2.5 million light years away is the most distant object easily seen with your unaided eye. Most other apparent denizens of the night sky -- stars...

An Iridium Flash Sunset
2.05.2000

Did you see that flash? Lasting only about 15 seconds, it's possible that nobody you ask can confirm it, but what you might have seen is sunlight reflecting off an orbiting Iridium satellite. Satellites of all types have been providing streaks and glints visible only since the launch of Sputnik I in 1957.

The Hunter s Stars
19.01.2012

Begirt with many a blazing star, Orion, the Hunter, is one of the most easily recognizable constellations. In this night skyscape from January 15, the hunter's stars rise in the northern hemisphere...

Vela Supernova Remnant in X-ray
12.06.1996

What happens when a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium, it heats up so much it glows in X-rays.

Volcano of Fire Erupts Under the Stars
10.03.2015

First, there was an unusual smell. Then there was a loud bang. But what appeared to the eye was the most amazing of all. While waiting near midnight to see a possible eruption of VolcАn de Fuego (Volcano of Fire) in Guatemala last month, a ready camera captured this extraordinary image.

The North Celestial Tower
16.07.2016

If you climbed to the top of this 13th century stone tower, it looks like you could reach out and touch the North Celestial Pole, the point at the center of all the star trail arcs.

A Year of Assessing Astronomical Hazards
31.12.2002

Could an asteroid destroy civilization on Earth? Mountain-sized space rocks could potentially impact the Earth causing global effects, and perhaps even be mistaken for a nuclear blast of terrestrial origin. Such large impacts are rare but have happened before. Modern telescopes have therefore begun to scan the skies for signs of approaching celestial hazards.

A High Energy Fleet
25.05.1997

Looking like a fleet of futuristic starcruisers, NASA's highly successful series of High Energy Astrophysical Observatory (HEAO) spacecraft appear poised over planet Earth. Labeled A, B, and C in this vintage illustration, the spacebased telescopes were known as HEAO-1, HEAO-2, and HEAO-3 respectively.

A High Energy Fleet
24.05.1998

Looking like a fleet of futuristic starcruisers, NASA's highly successful series of High Energy Astrophysical Observatory (HEAO) spacecraft appear poised over planet Earth. Labeled A, B, and C in this vintage illustration, the spacebased telescopes were known as HEAO-1, HEAO-2, and HEAO-3 respectively.

APOD: 2024 December 8 Б Aurora around Saturns North Pole
8.12.2024

Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's North Pole simultaneously during Cassini's final orbits around the gas giant in September 2017. During this time, Saturn's tilt caused its North Pole to be clearly visible from Earth.