Astronomy Picture Of the Day (APOD)Aurora Over Alaska
Higher than the highest mountain, higher than the highest airplane, lies the realm of the aurora. Aurora rarely reach below 60 kilometers, and can range up to 1000 kilometers. Aurora light results from solar electrons and protons striking molecules in the Earth's atmosphere.
560 Kilometers Above Europa
This is the closest photograph ever taken of Europa. Last December, NASA's spacecraft Galileo swept past the Jovian moon and took photographs which were released yesterday. Speculation that life-bearing oceans exist beneath Europa's surface caused NASA to put Galileo on orbits that approach Europa.
Rumors of a Strange Universe
In a meeting in California two weeks ago, unpublished results were presented indicating that most of the energy in our universe is not in stars or galaxies but is tied to space itself. In the language of cosmologists, a large cosmological constant is directly implied by new distant supernovae observations.
A Sky Full Of Hydrogen
Interstellar space is filled with extremely tenuous clouds of gas which are mostly Hydrogen. The neutral hydrogen atom (HI in astronomer's shorthand) consists of 1 proton and 1 electron. The proton and electron spin like tops but can have only two orientations; spin axes parallel or anti-parallel.
Eagle Eggs in M16
Star forming regions known as "EGGs" are uncovered at the end of this giant pillar of gas and dust in the Eagle Nebula (M16). EGGs, short for evaporating gaseous globules, are dense regions of mostly molecular hydrogen gas that fragment and gravitationally collapse to form stars.
Solar Eclipse: A Composite View
Yesterday, the Moon's shadow reached out and touched the Earth, treating a large portion of the Western Hemisphere to an Eclipse of the Sun. This composite image combines pictures of the Sun made from both Earth and space.
A Southern Sky View
From horizon to horizon, the night sky above Loomberah, New South Wales, Australia was photographed by astronomer Gordon Garradd on March 22, 1996. Garradd used a home made all-sky camera with a fish-eye lens, resulting in a circular 200 degree field of view.
The Solar Neighborhood
You are here. The orange dot in the above false-color drawing represents the current location of the Sun among local gas clouds in the spiral Milky Way Galaxy. These gas clouds are so thin that we usually see right through them. Nearly spherical bubbles surround regions of recent star formation.
The Lyman Alpha Forest
We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.
M104: The Sombrero Galaxy
What's going on in the center of this spiral galaxy? Named the Sombrero Galaxy for its hat-like resemblance, M104 features a prominent dust lane and a bright halo of stars and globular clusters.