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.
Moon Games
The Moon's measured diameter is around 3,476 kilometers (2,160 miles). But apparent angular size , or the angle covered by an object, can also be important to Moon enthusiasts .…
Galaxies on a String
Galaxies NGC 5216 (top right) and NGC 5218 really do look like they are connected by a string. Of course, that string is a cosmic trail of gas, dust, and stars about 22,000…
The International Space Station Transits the Sun
That's no sunspot. It's the International Space Station (ISS) caught by chance passing in front of the Sun. Sunspot s, individually, have a dark central umbra , a lighter…
The Milky Way Over Ontario
Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case earlier this month over Ontario , Canada , when part of a spectacular sky also became…
SDSSJ1430: A Galaxy Einstein Ring
What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured above on the left, the gravity of a normal white galaxy has…
IC 4406: A Seemingly Square Nebula
How can a round star make a square nebula? This conundrum comes to light when studying planetary nebulae like IC 4406. Evidence indicates that IC 4406 is likely a hollow cylinder,…
Central IC 1805
Cosmic clouds seem to form fantastic shapes in the central regions of emission nebula IC 1805. Of course, the clouds are sculpted by stellar winds and radiation from massive hot…
Spitzer's M101
Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier's famous catalog, but definitely not one of the least. About 170,000 light-years across, this…
When Storms Collide
These detailed Hubble Space Telescope close-ups feature Jupiter's ancient swirling storm system known as the Great Red Spot . They also follow the progress of two newer storm…
High Cliffs Surrounding Echus Chasma on Mars
What created this great cliff on Mars? Did giant waterfalls once plummet through its grooves? With a four-kilometer drop, this high cliff surrounding Echus Chasma , near an…
Happy People Dancing on Planet Earth
What are these humans doing? Dancing. Many humans on Earth exhibit periods of happiness, and one method of displaying happiness is dancing. Happiness and dancing transcend…
The Colliding Spiral Galaxies of Arp 271
What will become of these galaxies? Spiral galaxies NGC 5426 and NGC 5427 are passing dangerously close to each other, but each is likely to survive this collision. Most…
Crescent Rhea Occults Crescent Saturn
Soft hues, partially lit orbs, a thin trace of the ring, and slight shadows highlight this understated view of the majestic surroundings of the giant planet Saturn. Looking nearly…
M16 and the Eagle Nebula
Young star cluster M16 is surrounded by natal clouds of cosmic dust and glowing gas also known as The Eagle Nebula. This beautifully detailed image of the region includes…
Jupiter over Ephesus
A brilliant Jupiter shares the sky with the Full Moon tonight. Since Jupiter is near opposition , literally opposite the Sun in planet Earth's sky, Jupiter will rise near sunset…
Extra Galaxies
A careful look at the full field of view for this sharp image reveals a surprising number of galaxies both near and far toward the constellation Ursa Major . The most striking is…
Makemake of the Outer Solar System
Recently discovered Makemake is one of the largest objects known in the outer Solar System. Pronounced MAH-kay MAH-kay , this Kuiper belt object is only slightly smaller than…
Gas and Dust of the Lagoon Nebula
This beautiful cosmic cloud is a popular stop on telescopic tours of the constellation Sagittarius . Eighteenth century cosmic tourist Charles Messier cataloged the bright nebula…
Changes in Angular Mars
Does Mars always appear the same? No. As both Earth and Mars orbit the Sun, the apparent angular size of Mars changes as viewed from the Earth. Pictured above from Enschede ,…
A Dark Sky Over Death Valley
This eerie glow over Death Valley is in danger. Scrolling right will show a spectacular view from one of the darkest places left in the continental USA : Death Valley , California…
NGC 7331 and Beyond
Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way . About 50 million light-years distant in the northern constellation Pegasus , NGC 7331 was…
The Far 3kpc Arm
A major discovery was lurking in the data. By accident, while preparing a talk on the Galaxy's spiral arms for a meeting of the American Astronomical Society , Tom Dame…
Enhanced Color Caloris
The sprawling Caloris basin on Mercury is one of the solar system's largest impact basins. Created during the early history of the solar system by the impact of a large…
Planets and Fire by Moonlight
On July 5th, wandering planets, bright stars, and a young crescent Moon graced western skies after sunset. Arrayed along the solar system's ecliptic plane , the three celestial…
Viewing discoveries from 1 August 2008 through 9 July 2008.