Astronomy Picture Of the Day (APOD)Spicules: Jets on the Sun
Imagine a pipe as wide as a state and as long as half the Earth. Now imagine that this pipe is filled with hot gas moving 50,000 kilometers per hour. Further imagine that this pipe is not made of metal but a transparent magnetic field.
A Force from Empty Space: The Casimir Effect
This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.
Tonight: A Blue Moon
How often does a full moon occur twice in a single month? Exactly once in a Blue Moon. In fact, the modern usage of the term "Blue Moon" refers to the second Full Moon in a single month. Tonight's Blue Moon will be the first since November 2001.
While enjoying the spaceweather on a gorgeous summer evening in mid-July, astronomer Philippe Moussette captured this colorful fish-eye lens view looking north from the Observatoire Mont Cosmos, Quebec, Canada, planet Earth. In the foreground, lights along the northern horizon give an orange cast to the low clouds.
Steep cliffs drop into the rugged terrain of Melas Chasma in this stunning view from the Mars Express spacecraft orbiting the Red Planet. At a scale of 16 meters per pixel, the image data...
A Cygnus Star Field
In the constellation of the swan near the nebula of the pelican lies the gas cloud of the butterfly surrounding a star known as the hen. That star, given the proper name Sadr, is visible to the unaided eye but found here as the brightest object on the upper left.
Razorbacks in Endurance Crater
Over one year after its launch, robot geologist Opportunity has been spending recent sols on Mars inching its way down the slopes of Endurance crater. Littered with martian blueberries, some flat rocks within the crater also seem to have surprising razorbacks -- narrow slabs sticking up along their edges.
A Large Active Region Crosses the Sun
An unexpectedly large sunspot region is now crossing the Sun. The active region is home to rivers of hot plasma, explosive flares, strong magnetic fields, a powerful Coronal Mass Ejection (CME), and a sunspot group so large it can be seen by the protected eye without magnification.
A Solar Filament Lifts Off
Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above, which was captured in 2000 July by the Earth-orbiting TRACE satellite. The filament, although small compared...
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 suggestive appearance as well as its collision with the planet Jupiter!