Open Star Clusters M35 and NGC 2158
26.02.2025

Framed in this single, starry, telescopic field of view are two open star clusters, M35 and NGC 2158. Located within the boundaries of the constellation Gemini, they do appear to be side by side. Its stars concentrated toward the upper right, M35 is relatively nearby, though.

Tutulemma: Solar Eclipse Analemma
19.12.2009

If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun appear to move? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma.

Noctilucent Clouds and Aurora Over Scotland
19.08.2013

Why would the sky still glow after sunset? Besides stars and the band of our Milky Way galaxy, the sky might glow because it contains either noctilucent clouds or aurora. Rare individually, both are visible in the above time lapse movie taken over Caithness, Scotland, UK taken during a single night earlier this month.

Last Look at Plutos Charon Side
12.07.2015

Pluto surface is strange. As the robotic New Horizons barrels toward its closest approach to Pluto and its moons tomorrow, images already coming back show Pluto's surface to be curiouser and curiouser. The featured image, taken two days ago, shows the side of Pluto that always faces Pluto's largest moon Charon.

Solar System Portrait
13.02.2015

On another Valentine's Day 25 years ago, cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back one last time to make this first ever Solar System family portrait. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane.

Ancient Ogunquit Beach on Mars
7.05.2017

This was once a beach -- on ancient Mars. The featured 360-degree panorama, horizontally compressed, was taken by the robotic Curiosity rover currently exploring the red planet. Named Ogunquit Beach after its terrestrial counterpart, evidence...

APOD: 2024 May 26 Б A Solar Filament Erupts
25.05.2024

What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space, producing an energetic coronal mass ejection (CME).

Simulated Supergiant Star
21.12.2000

Looking for that perfect holiday gift for an astronomer? Consider this "star in a box". Of course, the box is actually a computational box consisting of a three dimensional grid of points, and the star is a virtual one whose physical properties and internal dynamics are numerically simulated at the points on the grid.

APOD is One Year Old Today
16.06.1996

The first Astronomy Picture of the Day (APOD) appeared one year ago today. Pictured above are Robert Nemiroff (left) and Jerry Bonnell (right), engaged in creating the APOD web pages. APOD started over speculative conversations on the ultimate value of the World Wide Web.

NGC 7635: The Bubble Nebula
21.04.2016

Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 7 light-year diameter bubble offers evidence of violent processes at work.