Astronomy Picture Of the Day (APOD)The Annotated Galactic Center
The sky toward the center of our Galaxy is filled with a wide variety of celestial wonders, many of which are visible from a dark location with common binoculars. Constellations near the Galactic Center include Sagittarius, Libra, Scorpius, Scutum, and Ophiuchus.
Comanche Outcrop on Mars Indicates Hospitable Past
Could life once have survived on Mars? Today, neither animal nor plant life from Earth could survive for very long on Mars because at least one key ingredient -- liquid water -- is essentially absent on the red planet's rusty surface.
The Local Fluff
The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). The ISM is not uniform, and shows patchiness even near our Sun.
Hole in the Sun
This ominous, dark shape sprawling across the face of the Sun is a coronal hole -- a low density region extending above the surface where the solar magnetic field opens freely into interplanetary space. Studied...
Brighter Than Mars
Even though you may have just read an email claiming Mars will be incredibly bright tonight, the brightest star on the horizon is not Mars. From central Iran on August 24th, the brightest star in this twilight desert skyview is Venus, aka the Evening Star.
M27: Not a Comet
While hunting for comets in the skies above 18th century France, astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his now famous not-a-comet list.
HD 10180: Richest Yet Planetary System Discovered
Do other rich planetary systems exist? Our Solar System has the most planets of any known star, most probably because it is so hard to detect planets around other stars. Sensitive measurements, though, have...
Galaxy Cluster Abell 1689 Magnifies the Dark Universe
What's the matter with this cluster of galaxies? To find out what forms matter takes in the Abell 1689 cluster requires not only deep images from telescopes like the Hubble Space Telescope, but detailed computer modeling as well. To start, almost every fuzzy yellow patch in the above image is an entire galaxy.
A Milky Way Shadow at Loch Ard Gorge
Have you ever seen the Milky Way's glow create shadows? To do so, conditions need to be just right. First and foremost, the sky must be relatively clear of clouds so that the long band of the Milky Way's central disk can be seen.
Hoags Object: A Strange Ring Galaxy
Is this one galaxy or two? This question came to light in 1950 when astronomer Art Hoag chanced upon this unusual extragalactic object. On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older.