Retrograde Mars
15.12.2003

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.

A Shadow on the Rings of Saturn
21.07.2004

This picture of Saturn could not have been taken from Earth. No Earth based picture could possibly view the night side of Saturn and the corresponding shadow cast across Saturn's rings. Since Earth is much closer to the Sun than Saturn, only the day side of the planet is visible from the Earth.

Eclipse Shirt
2.08.2008

Of course, everyone is concerned about what to wear to a solar eclipse. No need to worry though, nature often conspires to project images of the eclipse so that stylish and appropriate patterns adorn many visible surfaces - including clothing - at just the right time.

3D Mercury Transit
19.05.2016

On May 9, innermost planet Mercury crossed IN FRONT of the Sun. Though pictures project the event in only two dimensions, a remarkable three dimensional perspective on the transit is possible by free viewing this stereo pair.

Saturns Rings from the Inside Out
3.09.2017

What do Saturn's rings look like from Saturn? Images from the robotic spacecraft Cassini are providing humanity with this unprecedented vantage point as it nears the completion of its mission. Previous to Cassini's Grand Finale orbits, all images of Saturn's majestic ring system were taken from outside of the rings looking in.

Seeing Titan
17.08.2018

Shrouded in a thick atmosphere, Saturn's largest moon Titan really is hard to see. Small particles suspended in the upper atmosphere cause an almost impenetrable haze, strongly scattering light at visible wavelengths and hiding Titan's surface features from prying eyes.

An Artful Sky over Lofoten Islands
12.12.2022

Can the night sky be both art and science? If so, perhaps the featured image is an example. The digital panorama was composed of 10 landscape and 10 sky images all taken on the same night, from the same location, and with the same camera.

APOD: 2025 August 20 Б Perseid Meteors from Durdle Door
19.08.2025

What are those curved arcs in the sky? Meteors -- specifically, meteors from this year's Perseid meteor shower. Over the past few weeks, after the sky darkened, many images of Perseid meteors were captured separately and merged into a single frame, taken earlier.

Jets from Unusual Galaxy Centaurus A
31.05.2011

Jets of streaming plasma expelled by the central black hole of a massive spiral galaxy light up this composite image of Centaurus A. The jets emanating from Cen A are over a million light years long. Exactly how the central black hole expels infalling matter is still unknown.

Another Nearby Supernova in the Whirlpool Galaxy
5.06.2011

One of the brightest supernovas in recent years has just been recorded in the nearby Whirlpool galaxy (M51). Surprisingly, a seemingly similar supernova was recorded in M51 during 2005, following yet another one that occurred in 1994.