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.

Accretion Disk Simulation
12.03.2005

Don't be fooled by the familiar pattern. The graceful spiral structure seen in this computer visualization does not portray winding spiral arms in a distant galaxy of stars. Instead, the graphic shows spiral...

Massive Shell Expelling Star G79 29 0 46
25.09.2017

Stars this volatile are quite rare. Captured in the midst of dust clouds and visible to the right and above center is massive G79.29+0.46, one of less than 100 luminous blue variable stars (LBVs) currently known in our Galaxy.

Solstice Sun and Milky Way
21.12.2017

Welcome to December's solstice, first day of winter in the north and summer for the southern hemisphere. Astronomical markers of the seasons, solstice and equinox dates are based on the Sun's place in its annual journey along the ecliptic, through planet Earth's sky.

NGC 613 in Dust, Stars, and a Supernova
28.02.2018

Where did that spot come from? Amateur astronomer Victor Buso was testing out a new camera on his telescope in 2016 when he noticed a curious spot of light appear -- and remain. After reporting...

N11: Star Clouds of the LMC
29.04.2019

Massive stars, abrasive winds, mountains of dust, and energetic light sculpt one of the largest and most picturesque regions of star formation in the Local Group of Galaxies. Known as N11, the region...

Halloween and the Ghost Head Nebula
24.10.2021

Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere).

All of These Space Images are Fake Except One
9.11.2021

Why would you want to fake a universe? For one reason -- to better understand our real universe. Many astronomical projects seeking to learn properties of our universe now start with a robotic telescope taking sequential images of the night sky.

The Universe in Hot Gas
20.08.2002

Where is most of the normal matter in the Universe? Recent observations from the Chandra X-ray Observatory confirm that it is in hot gas filaments strewn throughout the universe. "Normal matter" refers to known elements and familiar fundamental particles.

APOD: 2023 February 15 Б Airglow Sky over France
15.02.2023

This unusual sky was both familiar and unfamiliar. The photographer's mission was to capture the arch of the familiar central band of our Milky Way Galaxy over a picturesque medieval manor. The surprise was that on this January evening, the foreground sky was found glowing in a beautiful but unfamiliar manner.