APOD: 2023 December 4 Б Plane Crossing Crescent Moon
4.12.2023

No, the Moon is not a bow, and no, it did not shoot out a plane like an arrow. What is pictured is a chance superposition. The plane's contrail would normally appear white...

Disorder in Stephan's Quintet
10.01.1998

What are five closely grouped galaxies doing in this image? The grouping is commonly known as Stephan's Quintet. Four of the galaxies show essentially the same redshift suggesting that they are at the same distance from us.

Earth s Shadow
20.08.2008

The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, the umbra has a circular cross section that can be most easily seen during a lunar eclipse. For example, last Saturday the Full Moon slid across the northern edge of the umbra.

Eclipse Shadow Cone Over Patagonia
4.08.2010

Sometimes, during a total eclipse of the Sun, a strange shadow of darkness can be seen stretching off into the distance. Called shadow cones, they are visible because the Earth's atmosphere is not completely transparent, scattering sunlight and hence appearing blue during the day.

Earthshadow and the Beehive
3.02.2018

The Earth's dark umbral shadow is shaped like a cone extending into space. Of course its circular cross section at the distance of the Moon is more easily seen during a lunar eclipse.

APOD: 2023 August 20 Б A Roll Cloud Over Wisconsin
20.08.2023

What kind of cloud is this? A type of arcus cloud called a roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud.

RCW 85
14.06.2024

From the 1960 astronomical catalog of Rodgers, Campbell and Whiteoak, emission region RCW 85 shines in southern night skies between bright stars Alpha and Beta Centauri. About 5,000 light years distant, the hazy interstellar cloud of glowing hydrogen gas and dust is faint.

Star Factory Messier 17
29.08.2024

A nearby star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this 1.5 degree wide field-of-view would span about 150 light-years.

Jupiter's Inner Moons
27.11.1997

The potato-shaped inner moons of Jupiter are lined-up in this mosaic "family portrait" of these tiny Jovian satellites. The individual images were recorded over the last year by NASA's Galileo spacecraft and are scaled to the moons' relative sizes.

Transit of Venus Stereogram
17.07.2004

Venus glides in front of an enormous solar disk in these two frames from the TRACE satellite imaging of the inner planet's 2004 transit. Arranged in a "right/left" stereogram, the frames are intended...