Astronomy Picture Of the Day (APOD)Cygnus Loop Supernova Shockwave
15,000 years ago a star in the constellation of Cygnus exploded. This picture shows a portion of a shockwave from this supernova explosion still expanding past nearby stars. The collision of this gaseous...
"Yes, I have been to Barsoom again ..." begins John Carter in Edgar Rice Burroughs' 1913 science fiction classic "The Gods of Mars". In Burroughs' novels describing Carter's adventures on Mars, "Barsoom" is the local name for the red planet.
The Exploration of Mars
Thirty years ago NASA's exploration of Mars began. In July of 1965 the Mariner 4 spacecraft flew within 6,000 miles of Mars and returned 21 pictures of the mysterious red planet. NASA...
The Crater Chain
NASA's robot spaceprobe Voyager 1, took this closeup image of the surface of Jupiter's crater scarred moon Callisto in 1979. A mysterious chain of craters is seen to extend diagonally across the image (upper left to lower right). What could cause the craters to line up in such a regular fashion?
Comet Impacts on Jupiter
In July of 1994, pieces of Comet Shoemaker-Levy 9, also known as the "string of pearls" comet, collided with the planet Jupiter. As the comet fragments smashed in to Jupiter, the resulting explosions scattered large quantities of dusty cometary debris into the Jovian atmosphere.
A String Of Pearls
Comet Shoemaker-Levy 9, named after its co-discoverers, was often referred to as the "string of pearls" comet. It is famous for its unusual appearance as well as its collision with the planet Jupiter!
Eta Carinae Before Explosion
The star Eta Carinae, at the center of the photo, will likely destroy itself in a spectacular explosion in a few million years - or sooner! Currently it is one of the brightest, most massive, and least stable stars known. Much of the gas in this Hubble Space Telescope photograph was blown off the star itself.
Microlensing of the Einstein Cross
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 gravitational effect...
Abell 2218: A Galaxy Cluster Lens
Sometimes one of the largest concentrations of mass known can act like a lens. Almost all of the bright objects in this image are galaxies in the cluster known as Abell 2218. The cluster...
A Meteoric View of Apollo 13
Meteors, also called shooting stars, normally begin as bits of dust from the tails of comets or even small pieces chipped off asteroids. Falling toward Earth, these particles enter the atmosphere at extremely high speeds. Friction with the air heats them up and makes them glow brightly.