Three Month Composite of Comet Holmes
5.02.2008

How has Comet Holmes changed? Since brightening unexpectedly by nearly one million fold in late October, the last three months have found the coma of Comet 17P/Holmes both expanding and fading. This spectacular composite image shows how the coma and tail of Comet Holmes have changed.

Full Venus and Crescent Moon Rise
14.04.2016

Inner planet Venus and a thin crescent Moon are never found far from the Sun in planet Earth's skies. Taken near dawn on April 6, this timelapse composite shows them both rising just before the Sun. The mountaintop Teide Observatory domes on the fortunate island of Tenerife appear in silhouette against the twilight.

Equinox: Analemma over the Callanish Stones
23.09.2018

Does the Sun return to the same spot on the sky every day at the same time? No. A more visual answer to that question is an analemma, a composite image taken from the same spot at the same time over the course of a year.

Half Sun with Prominence
2.11.2020

What's happening to the Sun? Clearly, the Sun's lower half is hidden behind a thick cloud. Averaging over the entire Earth, clouds block the Sun about 2/3rds of the time, although much less over many land locations. On the Sun's upper right is a prominence of magnetically levitating hot gas.

APOD: 2026 June 1 Б Saturn at Night
1.06.2026

Telescopic views of Saturn and its beautiful rings often make it the star of star parties. But this stunning view of the outer gas gaint planet's rings and night side just isn't possible from telescopes in the vicinity of planet Earth.

Julius Caesar and Leap Days
29.02.2024

In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long.

Mauna Kea Shadow Play
1.03.2008

Just opposite the setting Sun, the already-eclipsed Moon rose over the Hawaiian Islands on February 20. A view near the 14,000 foot peak of volcanic Mauna Kea on the Big Island, a popular spot for astronomers, offered this remarkable play of shadows and sunlight.

Over the Top
19.06.2014

The central bulge of our Milky Way Galaxy rises above a sea of clouds in this ethereal scene. An echo of the Milky Way's dark dust lanes, the volcanic peak in foreground silhouette is on France's Réunion Island in the southern Indian Ocean.

A Full Sky Aurora Over Norway
1.01.2017

Higher than the highest building, higher than the highest mountain, higher than the highest airplane, lies the realm of the aurora. Auroras rarely reach below 60 kilometers, and can range up to 1000 kilometers. Aurora light results from energetic electrons and protons striking molecules in the Earth's atmosphere.

Eclipse under the ISS
27.06.2020

The dark shadow of the New Moon reached out and touched planet Earth on June 21. A high definition camera outside the International Space Station captured its passing in this snapshot from low Earth orbit near the border of Kazakhstan and China.