Astronomy Picture Of the Day (APOD)Europa Rotating
Evidence has been mounting that beneath the vast planes of ice that cover Europa lies water -- liquid oceans that might be home to alien life. The smallest of Jupiter's Galilean Moons (which include Io, Ganymede, and Callisto), Europa's deep interior is composed of mostly of silicate rock.
Billows of Smog in the Outer Galaxy
Our Galaxy is filled with gas. Most of this gas is hydrogen, some is helium, but there is a trace amount of relatively heavy molecules, including carbon monoxide (CO) - a component of smog. The above wide-angle radio CO image shows the incredibly diverse structures that the molecular interstellar medium forms.
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 to use Brahe's data...
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.
NGC 1410/1409: Intergalactic Pipeline
These two galaxies are interacting in a surprising way, connected by a "pipeline" of obscuring material that runs between them over 20,000 light-years of intergalactic space. Silhouetted by starlight, the dark, dusty ribbon appears to stretch from NGC 1410 (the galaxy at the left) and wrap itself around NGC 1409 (at right).
X-rays From The Cat's Eye
Haunting patterns within planetary nebula NGC 6543 readily suggest its popular moniker -- the Cat's Eye nebula. In 1995, a stunning false-color optical image from the Hubble Space Telescope detailed the swirls of this glowing nebula, known to be the gaseous shroud expelled from a dying sun-like star about 3,000 light-years from Earth.
Watch the Sky Rotate
If you could watch the sky for an entire night, what would you see? The above time-lapse sequence from the CONtinuous CAMera (CONCAM) project shows the answer for the skies above Kitt Peak National Observatory on 2000 December 23.
A Cosmic Call to Nearby Stars
If you could send a message to an alien civilization, what would you say? The people from the Cosmic Call project sent the above image as the first page of a longer message. The message was broadcast toward local stars by a radio telescope in
Help NASA Classify Martian Craters
The large Martian crater above just left of center: is this a fresh crater, a degraded crater, or a ghost crater? Complex image recognition tasks like these are currently done more reliably by a human than a computer.
Tycho Brahe Measures the Sky
Tycho Brahe was the most meticulous astronomical observer of his time. Brahe, who lived between 1546 and 1601, set out to solve the day's most pressing astronomical problem: to determine whether the Earth or the Sun was at the center of the Solar System.