Browse NASA Astronomy Picture of the Day archive by date and media: Archive Discoveries
Browse the NASA APOD archive without needing the exact date first. Filter by media type and keep moving deeper into older images and videos.
Dark Bok Globules in IC 2944
Explanation : The dark spots in the above picture are not photographic defects but an unusual type of interstellar cloud known as a Bok globule . Bok globules, named after…
CG4: A Ruptured Cometary Globule
Explanation : The odd looking “creature” to the right of center in the above photo is a gas cloud known as a cometary globule . This globule, however, has ruptured. Cometary…
HET: The New Largest Optical Telescope
Explanation : Most of our universe is too dim to see. To peer into our cosmos' unknown depths, astronomers must deploy new tools - and the classic new tool is a larger telescope.…
Carl Sagan 1934-1996
Explanation : Carl Sagan died last Friday at the age of 62. Sagan was the world's most famous astronomer. Among his many activities as a scientist, he contributed to the discovery…
An Earth Ornament
Explanation : The Apollo 8 astronauts spent the 1968 Christmas Season in lunar orbit, returning with striking images of the Moon and Earth from space which inspired the world.…
A Mirry Christmas
Explanation : Thinking about spending the Holiday Season in low Earth orbit? Astronaut John Blaha and his cosmonaut colleagues Valeri Korzun and Alexander Kaleri are doing just…
The Hills of Ganymede
Explanation : This computer generated 3D close-up view of Jupiter's large moon Ganymede was created using image data from NASA's Galileo spacecraft. Simulating stereo vision by…
18 Miles From Deimos
Explanation : Diminutive Deimos is the smallest of the two tiny Moons of Mars. Potato shaped and barely 6 miles wide this asteroid-like body was visited by the Viking 2 orbiter in…
Sun and Winter Solstice 1996
Explanation : Today is the Winter Solstice for 1996. After steadily sinking in Northern Hemisphere skies , the Sun is now at its lowest declination - marking the first day of…
The UV SMC from UIT
Explanation : Translated from the “acronese” the title reads - The U ltra V iolet S mall M agellanic C loud from the U ltraviolet I maging T elescope. FYI, the four ultraviolet…
Comet Hale-Bopp Inbound
Explanation : Headed toward the inner Solar System, the much anticipated Comet Hale-Bopp has promised to put on a big show next spring. The comet's apparent brightness is…
A Sky Full Of Hydrogen
Explanation : Interstellar space is filled with extremely tenuous clouds of gas which are mostly Hydrogen. The neutral hydrogen atom (HI in astronomer's shorthand) consists of 1…
Mariner's Mercury
Mercury, the closest planet to the Sun, remains the most mysterious of the Solar System's inner planets. Hiding in the Sun's glare it is a difficult target for Earth bound…
Nebula Nova Cygni Turns On
Explanation : Old photographs show no evidence of the above nebula. In 1992, a white dwarf star in Cygnus blew off its outer layers in a classical nova explosion : an event called…
Microlensing of the Einstein Cross
Explanation : The famous “Einstein Cross” is a case where a single object is seen four times. Here a very distant QSO happened to be placed right behind a massive galaxy . The…
Our Solar System from Voyager
Explanation : After taking spectacular pictures of our Solar System's outer planets, Voyager 1 looked back at six planets to take our Solar System's first family portrait. Here…
Disorder in Stephan's Quintet
Explanation : Five closely grouped galaxies are visible in this image made using the Kitt Peak National Observatory 2.1 meter telescope. The grouping is commonly known as…
The Milky Way Through the Summer Triangle
Explanation : There are more than a few stars in our Galaxy. The light from many of them combines to appear as a wisp of faint light across the night sky - the Milky Way . In the…
Starburst Ring in Galaxy NGC 1317
Explanation : Where do stars form? A typical place is an area of dense nebular gas common to arms in spiral galaxies . Sometimes, however, a burst of star formation can occur with…
Comet Halley's Nucleus
Explanation : Here is what a comet nucleus really looks like. For all active comets except Halley , it was only possible to see the surrounding opaque gas cloud called the coma .…
Callisto Full Face
Explanation : Callisto's surface shows its age. While probably formed at the same time as Io , the difference between the surfaces of these two moons of Jupiter could hardly be…
Degas Ray Crater on Mercury
Explanation : Like the Earth's Moon, Mercury is scarred with craters, testifying to an intense bombardment during the early history of the Solar System. In 1974, the Mariner 10…
Planetary Systems Now Forming in Orion
Explanation : How do planets form? Astronomers are finding out by studying one of the most interesting of all astronomical nebulae known, the Great Nebula in Orion . Insets to…
Globular Cluster M3
Explanation : This huge ball of stars predates our Sun. Long before mankind evolved, before dinosaurs roamed , and even before our Earth existed, ancient globs of stars condensed…
Viewing discoveries from 29 December 1996 through 6 December 1996.