Red Aurora Over Australia
29.01.2017

Why would the sky glow red? Aurora. A solar storm in 2012, emanating mostly from active sunspot region 1402, showered particles on the Earth that excited oxygen atoms high in the Earth's atmosphere. As the excited element's electrons fell back to their ground state, they emitted a red glow.

NGC 246 and the Dying Star
18.04.2006

Appropriately nicknamed "the Skull Nebula", planetary nebula NGC 246 really does surround a dying star some 1,600 light-years away in the constellation Cetus. Expelled over a period of thousands of years, the lovely, intricate nebula is the outer atmosphere of a once sun-like star.

A Perseid Meteor
11.08.2002

The ongoing Perseid Meteor Shower should be at its strongest on August 12 and 13. The best time to watch will be between 2:00 AM and dawn on Monday morning (so plan on setting your alarm tonight!) and then again on Tuesday.

Red Aurora Over Australia
1.02.2012

Why would the sky glow red? Aurora. Last week's solar storms, emanating mostly from active sunspot region 1402, showered particles on the Earth that excited oxygen atoms high in the Earth's atmosphere. As the excited element's electrons fell back to their ground state, they emitted a red glow.

APOD: 2023 July 24 Б Chemicals Glow as a Meteor Disintegrates
24.07.2023

Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured here is a fireball, a disintegrating meteor that was not only one of the brightest the photographer has ever seen, but colorful.

Animation: Black Hole Star Shredder
27.04.2021

What happens if a star gets too close to a black hole? The black hole can rip it apart -- but how? It's not the high gravitational attraction itself that's the problem -- it's the difference in gravitational pull across the star that creates the destruction.

APOD: 2025 January 7 Б A New Years Aurora and SAR Arc
7.01.2025

It was a new year, and the sky was doubly red. The new year meant that the Earth had returned to its usual place in its orbit on January 1, a place a few days before its closest approach to the Sun.

Blue Flash
9.01.2002

Difficult to observe, the momentary green flash above the rising or setting sun has been documented as a phenomenon caused by the atmospheric bending or refraction of sunlight. Like a weak prism, the Earth's atmosphere breaks white sunlight into colors, bending red colors slightly and green and blue colors through increasingly larger angles.

APOD: 2024 June 18 Б Gigantic Jets over Himalayan Mountains
18.06.2024

Yes, but can your thunderstorm do this? Pictured here are gigantic jets shooting up from a thunderstorm last week toward the Himalayan Mountains in China and Bhutan. The composite image captured four long jets that occurred only minutes apart.

Compton Observatory In Orbit
8.04.2000

Nine years ago the massive Compton Gamma Ray Observatory was deployed in low earth orbit. Sparkling interior reflections and the bright limb of the Earth are visible in this 1991 window view of Compton's release by the crew of the Space Shuttle Atlantis.