Astronomy Picture Of the Day (APOD)Oceans Under Jupiters Callisto
Why does Jupiter's moon Callisto alter the magnetic field of Jupiter in its vicinity? Callisto itself does not have a strong magnetic field. One possible answer is that Callisto harbors sub-surface oceans of electrically conducting salt-water. This hypothesis was bolstered recently by a new analysis of how Callisto creates and dissipates heat.
Star Cluster R136 Bursts Out
In the center of star-forming region 30 Doradus lies a huge cluster of the largest, hottest, most massive stars known. Known as R136, the cluster's energetic stars are breaking out of the cocoon of gas and dust from which they formed.
M57: The Ring Nebula
Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. This planetary nebula's simple, graceful appearance is thought to be due to perspective -- our view from planet Earth looking straight into what is actually a barrel-shaped cloud of gas shrugged off by a dying central star.
A Daytime Fireball in 1944
While stationed in central Africa in December 1944, Norman Appleton witnessed a meteor so bright he remembered it his entire life. Right before his eyes a tremendous smoking fireball streaked across the daytime sky. Years later, as an accomplished member of the Guild
Martian Dust Storm
If you've been unhappy with the weather on Earth, check out Mars, now in the grip of a planet-wide dust storm. Above, observations from the orbiting Mars Global Surveyor (MGS) spacecraft illustrate the storm's progress through July 21.
When the Moon's shadow reached out and touched Earth's southern hemisphere on 2001 June 21, the first total solar eclipse of the 21st century began. Starting in the Atlantic, the dark, central...
Hot Gas Halo Detected Around Galaxy NGC 4631
Is our Milky Way Galaxy surrounded by a halo of hot gas? A step toward solving this long-standing mystery was taken recently with Chandra X-ray observations of nearby galaxy NGC 4631. In the above composite picture, newly resolved diffuse X-ray emission is shown in blue, superposed on a HST image showing massive stars in red.
The Red Spider Planetary Nebula
Oh what a tangled web a planetary nebula can weave. The Red Spider Planetary Nebula shows the complex structure that can result when a normal star ejects its outer gases and becomes a white dwarf star.
Atlantis to Orbit
Birds don't fly this high. Airplanes don't go this fast. The Statue of Liberty weighs less. No species other than human can even comprehend what is going on, nor could any human just a millennium ago. The launch of a rocket bound for space is an event that inspires awe and challenges description.
NGC 1977: Blue Reflection Nebula in Orion
The Orion Nebula is visible to the unaided eye as a fuzzy patch near the famous belt of three stars in the Orion. The above picture captures a part of the Orion Nebula that primarily reflects light from bright Orion stars.