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.
Southwest Mercury
The planet Mercury resembles a moon. Mercury 's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter 's moon Ganymede and…
Mercury: A Cratered Inferno
Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. Mercury 's diameter is about 4800 km, while the Moon 's is slightly less at about 3500 km…
In the Center of Spiral M77
What is happening in the center of nearby spiral galaxy M77? To find out, astronomers used the Hubble Space Telescope to peer deep into the dusty chaos of this active galactic…
M77: Spiral with a Strange Glow
Why is M77 surrounded by an ultraviolet glow? M77 , also called NGC 1068, appears at first sight to be a relatively normal barred spiral galaxy . But when photographed in the…
The High Energy Crab Nebula
This is the mess that is left when a star explodes. The Crab Nebula is so energetic that it glows in every kind of light known. Shown above are images of the Crab Nebula from…
Volcano Euboea Fluctus On Io
Jupiter 's moon Io is turning out to be our Solar System 's geologic powerhouse. The churning moon was photographed again just recently on June 27th and again shows signs of…
Two Billion Years After the Big Bang
What did the universe look like two billion years after the Big Bang ? According to this computer model , the universe was filled with irregular looking objects like the ones…
The Largest Impact Crater
What is the largest known impact crater in the Solar System? Over 1300 miles across, the South Pole -Aitken Basin on the farside of Earth's Moon holds that distinction. Circled…
Watch Galaxies Form
Snips and snails and puppy dog tails, is that what galaxies were made of? In a report released yesterday and soon to be published in Nature , astronomers have imaged an…
IRTF: Scanning the Infrared Skies
Above, NASA's Infrared Telescope Facility (IRTF) poses in front of a starry background. Located on top of Hawaii 's towering volcano Mauna Kea , the IRTF is the premier telescope…
The Pleiades Star Cluster
It is the most famous star cluster on the sky. The Pleiades can be seen without binoculars from even the depths of a light-polluted city . Also known as the Seven Sisters and M45…
Sirius: The Brightest Star in the Night
Sirius is the brightest star in the night sky. Intrinsically, Sirius is over 20 times brighter than our Sun and over twice as massive. As Sirius is 8.7 light years distant, it is…
VLT: A New Largest Optical Telescope
What is the largest telescope in the world? In the optical, this title was long held by the Hale 200-inch , and is presently held by the Keck telescopes in Hawaii. But an even…
Kepler Discovers How Planets Move
Johannes Kepler used simple mathematics to describe how planets move. Kepler was an assistant to the most accurate astronomical observer of the time, Tycho Brahe . Kepler was able…
Galileo Demonstrates the Telescope
Galileo Galilei made a good discovery great. Upon hearing at age 40 that a Dutch optician had invented a glass that made distant objects appear larger, Galileo crafted his own…
M17: The Majestic Swan Nebula
What unusual eggs have been laid by this majestic swan ? The star forming region above, known as Swan Nebula , is the home of hot red-glowing gas , dark lanes of dust , bright…
NGC 5882: A Small Planetary Nebula
Will most stars one day look like this? Pictured above is the planetary nebula NGC 5882, captured by the Hubble Space Telescope . Although planetary nebulae can appear similar to…
Galileo Zooms in on Jupiter's Red Spot
What does the largest storm system ever recorded look like close-up? This storm system is Jupiter 's Great Red Spot and it was captured recently in detail by the robot spacecraft…
A Wolf-Rayet Star Bubble
What's a Wolf-Rayet star, and how did it create that spherical bubble and sweeping arc? A Wolf-Rayet star is a star that originated with a mass over 40 times that of our Sun . An…
Luna 9: First Soft Lander
The Luna 9 spacecraft above performed the first soft landing on another planetary body. Following a series of failures, the Soviet probe touched down in the Moon's Oceanus…
Why is QSO 1229+204 so Bright?
What causes the center of this barred spiral galaxy to light up brighter than almost anything in the universe? The quasar there is a good fraction of the way across our observable…
NGC 3293: A Bright Young Open Cluster
Hot Blue stars shine brightly in this beautiful, recently formed galactic or “open” star cluster. Open cluster NGC 3293 is located in the constellation Carina , lies at a distance…
Arp 230: Two Spirals in One?
Is this one galaxy or two? Analysis of Arp 230 has shown evidence that this seemingly single spiral galaxy is actually the result of the recent collision of two spiral galaxies .…
A Close-Up of the Lagoon's Hourglass
In the central part of the Lagoon Nebula lies the above pictured Hourglass Nebula . In this region of recent star formation, obscuring dark lanes of dust permeate the red-glowing…
Viewing discoveries from 13 September 1996 through 21 August 1996.