When Rainbows Smile
11.03.2022

Want to see a rainbow smile? Look near the zenith (straight up) when the sun is low in the sky and you might. This example of an ice halo known as a circumzenithal arc was captured above a palm tree top from Ragusa, Sicily on February 24.

APOD: 2024 May 30 Б A Lunar Corona over Paris
30.05.2024

Why does a cloudy moon sometimes appear colorful? The effect, called a lunar corona, is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently.

APOD: 2025 December 16 Б Andromeda and Sprites over Australia
16.12.2025

WhatБs happening over that tree? Two very different things. On the left is the Andromeda galaxy, an object that is older than humanity and will last billions of years into the future. Andromeda (M31) is similar in size and shape to our own Milky Way Galaxy.

Shadow at the Lunar South Pole
28.11.1995

In 1994, the space probe Clementine spent 70 days in lunar orbit mapping the Moon's surface. Shown above is a dramatically detailed composite view centered on the Moon's South Pole constructed from 1500 Clementine images.

Veins of Heaven
31.07.2014

Transfusing sunlight through a a still dark sky, this exceptional display of noctilucent clouds was captured earlier this month above the island of Gotland, Sweden. From the edge of space, about 80 kilometers above...

Milky Way over Yellowstone
29.01.2020

The Milky Way was not created by an evaporating lake. The pool of vivid blue water, about 10 meters across, is known as Silex Spring and is located in Yellowstone National Park in Wyoming, USA. Steam rises off the spring, heated by a magma chamber deep underneath known as the Yellowstone hotspot.

Lunar Dust and Duct Tape
29.05.2021

Why is the Moon so dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, the history of constant micrometeorite bombardment has blasted away at the rocky surface creating a layer of powdery lunar soil or regolith.

Galaxy by the Lake
10.09.2022

This 180 degree panoramic night skyscape captures our Milky Way Galaxy as it arcs above the horizon on a winter's night in August. Near midnight, the galactic center is close to the zenith with the clear waters of Lake Traful, Neuquen, Argentina, South America, planet Earth below.

Lunar Dust and Duct Tape
1.05.1999

Why is the Moon dusty? On Earth, rocks are weathered by wind and water, creating soil and sand. On the Moon, the long history of micrometeorite bombardment has blasted away at the rocky surface creating a layer of powdery lunar soil or regolith. This lunar regolith could be a scientific and industrial bonanza.

Ice Fishing for Cosmic Neutrinos
29.04.2001

Scientists are melting holes in the bottom of the world. In fact, several holes have been melted near the South Pole, and they are now being used as astronomical observatories. Astronomers with the Antarctic Muon and Neutrino Detector Array (AMANDA) lower into each vertical lake a string knotted with basketball-sized light detectors.