A Fog Bow Over California
15.11.2006

Is that white arch real? What is being seen is a fogbow, a reflection of sunlight by water drops similar to a rainbow but without the colors. The fog itself is not confined to an arch -- the fog is mostly transparent but relatively uniform.

Moon Over Andromeda
28.12.2006

The Great Spiral Galaxy in Andromeda (aka M31), a mere 2.5 million light-years distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small...

Red Sprite Lightning with Aurora
22.05.2013

What's that in the sky? It is a rarely seen form of lightning confirmed only about 25 years ago: a red sprite. Recent research has shown that following a powerful positive cloud-to-ground lightning...

Bright Spiral Galaxy M81
18.11.2014

One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy can be found toward the northern constellation of the Great Bear (Ursa Major).

Approaching the Bubble Nebula
31.05.2017

What would it look like to approach the Bubble Nebula? Blown by the wind and radiation from a massive star, this bubble now spans seven light-years in diameter. The hot star inside is thousands of times more luminous than our Sun, and is now offset from the nebula's center.

Venusian Volcano Imagined
27.10.2020

What would an erupting volcano on Venus look like? Evidence of currently active volcanoes on Venus was announced earlier this year with the unexplained warmth of regions thought to contain only ancient volcanoes. Although...

Deepscape at Yacoraite
8.05.2021

In this evocative night scene a dusty central Milky Way rises over the ancient Andean archaeological site of Yacoraite in northwestern Argentina. The denizens of planet Earth reaching skyward are the large Argentine saguaro cactus currently native to the arid region.

The Horsehead Nebula Region without Stars
29.08.2022

The famous Horsehead Nebula in Orion is not alone. A deep exposure shows that the dark familiar shaped indentation, visible just right of center, is part of a vast complex of absorbing dust and glowing gas.

APOD: 2025 April 16 Б Halo of the Cats Eye
16.04.2025

What created the unusual halo around the Cat's Eye Nebula? No one is sure. What is sure is that the Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae on the sky.

APOD: 2025 May 20 Б Milky Way over Maunakea
20.05.2025

Have you ever seen the band of our Milky Way Galaxy? In a clear sky from a dark location at the right time, a faint band of light becomes visible across the sky. Soon after your eyes become dark adapted, you might spot the band for the first time. It may then become obvious.