Moon Pi and Mountain Shadow
14.03.2024

What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is Pi radians (aka 180 degrees) from the Sun in ecliptic longitude.

Crescent Neptune and Triton
14.04.2013

Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The elegant picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach.

Two Views, Two Crescents
11.11.2010

Venus rose in a glowing dawn sky on November 5th, just before the Sun. For early morning risers, its brilliant crescent phase was best appreciated with binoculars or a small telescope. On that...

Moon Pi and Mountain Shadow
14.03.2025

What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is Pi radians (aka 180 degrees) from the Sun in ecliptic longitude.

Crescent Neptune and Triton
19.06.2001

Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The above picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach.

Crescent Neptune and Triton
18.06.2006

Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The above picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach.

Reunion Island Eclipse
3.09.2016

The New Moon's dark shadow crossed planet Earth on September 1. In silhouette the Moon didn't quite cover the Sun though, creating an an annular solar eclipse. The shadow's narrow central path was about 100 kilometers wide at maximum eclipse.

Mars Rocks, Sojourner Rolls
14.08.1997

This sharp color image featuring Mars rock Yogi and the rolling Sojourner robot shows off Yogi's startling two-toned surface. Yogi appears to be leaning into the prevailing winds causing some to suggest that its color contrast may be caused by the accumulation of rust colored dust on its windward face.

Crescents of Titan and Dione
29.03.2005

What would it be like to see a sky with many moons? Such is the sky above Saturn. When appearing close to each other, moons will show a similar phase. A view with...

APOD: 2025 August 30 Б A Two Percent Moon
30.08.2025

A young crescent moon can be hard to see. That's because when the Moon shows it's crescent phase (young or old) it can never be far from the Sun in planet Earth's sky.