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.
The Equal Night
Yesterday the Sun crossed the celestial equator heading south, marking the Equinox -- the first day of Autumn in the northern hemisphere and Spring in the south . Equinox means…
M55: Globular Star Cluster
The fifty-fifth entry in Charles Messier's catalog, M55 is a large and lovely globular cluster of around 100,000 stars. Only 20,000 light-years away in the constellation…
XZ Tauri System Ejects Gas Bubble
Why is the binary star system XZ Tauri emitting a hot bubble of expanding gas? Although astronomers can only presently speculate, the Hubble Space Telescope clearly documents this…
Gangly Spiral Galaxy NGC 3184
NGC 3184 is a large spiral galaxy with a small nucleus and long sprawling spiral arms. Although NGC 3184 contains hundreds of billions of stars, the blue color of its spiral arms…
M17: Omega Nebula Star Factory
In the depths of the dark clouds of dust and molecular gas known as M17, stars continue to form. Visible in the above recently released representative-color photograph of M17 by…
Approaching the International Space Station
Last Monday the crew of Space Shuttle Atlantis took in this view as they approached the developing International Space Station (ISS). From top to bottom, the astronauts saw a…
Saturnian Aurora
Girdling the second largest planet in the Solar System, Saturn's Rings are one of the most spectacular sights for earthbound telescopes. This image from the orbiting Hubble Space…
X-Ray Earth
Above is a picture of the Earth in x-rays , taken in March of 1996 from the orbiting Polar satellite . Most of the planet is dark with superposed continent and coordinate grids,…
Aurora In West Texas Skies
The aurora borealis, or northern lights , are not a common sight in the southwestern United States. But a strong solar coronal mass ejection in early August triggered geomagnetic…
M82's Middle Mass Black Hole
Black holes are probably the most bizarre creatures in the modern astronomical zoo. And after years of pondering black holes as either stellar mass objects seen in binary star…
Comet LINEAR: Fade To Black
Only last month the stage was set for Comet LINEAR (C/1999S4 LINEAR) to become the first “naked-eye” comet of Y2K. It didn't fill that role, of course, but it did turn in a very…
Slightly Above Mars Pathfinder
If you could have hovered above the Pathfinder mission to Mars in 1997, this is what you might have seen. Directly below you is the control tower of Sagan Memorial Station . Three…
Antarctic Ozone Hole Widens
It's back, and it's bigger than ever. The ozone hole that has been a cause of concern in recent years has again reformed over Earth's South Pole . The seasonal recur rence of the…
White Dwarf Stars Cool
Diminutive by stellar standards , white dwarf stars are also intensely hot ... but they are cooling. No longer do their interior nuclear fires burn , so they will continue to cool…
X-Ray Moon and X-Ray Star
An x-ray star winks out behind the Moon in these before (left) and after views of a lunar occultation of the galactic x-ray source designated GX5-1 . The false color images were…
Andromeda Island Universe
How far can you see? The most distant object easily visible to the unaided eye is M31 , the great Andromeda Galaxy some two million light-years away. Without a telescope, even…
IC 418: The Spirograph Nebula
What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool , planetary nebula IC 418 shows patterns…
Emerging Planetary Nebula CRL 618
CRL 618 may look to some like an Olympian declaring victory. Only a few hundred years ago, however, CRL 618 appeared as a relatively modest red giant star . Since then it has run…
CFHT Star Trails
High atop a dormant volcano in Hawaii , an eye 3.6-meters wide stares at a faint light on the night sky. Unlike a human eye , which collects light for only a fraction of a second…
Aurora Persei
Last month, skywatchers were treated to an unexpected coincidence: bright aurorae occurred during the Perseid Meteor Shower . The above picture was taken August 12 and captures…
Henrietta Leavitt Calibrates the Stars
Humanity's understanding of the relative brightness and variability of stars was revolutionized by the work of Henrietta Swan Leavitt (1868-1921). Working at Harvard College…
X-Ray Moon
This x-ray image of the Moon was made by the orbiting ROSAT ( Röntgensatellit ) Observatory in 1990. In this digital picture, pixel brightness corresponds to x-ray intensity.…
SOHO Sungrazer
SOHO , the space-based SOlar and Heliospheric Observatory, has become by far the reigning champion facility for discovering comets, its total having recently reached 200 . As…
Full Throttle For Deep Space 1
At full throttle the Deep Space 1 spacecraft's innovative ion drive produces about 1/50th of a pound of thrust ... a force so great that it would just about hold up a piece of…
Viewing discoveries from 23 September 2000 through 31 August 2000.