Astronomy Picture Of the Day (APOD)Ganymede: The Largest Moon in the Solar System
If Ganymede orbited the Sun, it would be considered a planet. The reason is that Jupiter's moon Ganymede is not only the largest moon in the Solar System, it is larger than planets Mercury and Pluto.
The Long Jet of Pictor A
A jet stretching nearly a million light years has been imaged emanating from galaxy Pictor A. The thin jet of electrons and protons shoots out at nearly light-speed likely from the vicinity of a large black hole at the galaxy center.
The Milky Way Near the Southern Cross
This breathtaking patch of sky would be above you were you to stand at the South Pole of the Earth. Just above and to the right of this photograph's center are the four stars that mark the boundaries of the famous Southern Cross.
The Last Moon Shot
In 1865 Jules Verne predicted the invention of a space capsule that could carry people. In his science fiction story "From the Earth to the Moon", he outlined his vision of a cannon in Florida so powerful that it could shoot a "Projectile-Vehicle" carrying three adventurers to the Moon.
APOD is Five Years Old Today
Welcome to the sixth year of Astronomy Picture of the Day (APOD)! Above are the industrious Robert Nemiroff (left) and persistent Jerry Bonnell (right), still engaged in creating the APOD web pages. As suggested...
X-Rays From The Perseus Cluster Core
The Perseus Cluster of thousands of galaxies, 320 million light-years distant, is one of the most massive objects in the Universe. At its core lies the giant cannibal galaxy Perseus A (NGC 1275), accreting matter as gas and galaxies fall into it.
A Slice of the Universe with 2dF
What can 100,000 galaxies tell you? Perhaps the structure and composition of the universe. Astronomers using the Two Degree Field (2dF) spectrograph on the Anglo-Australian Telescope (AAT) in Australia have now measured the redshifts of over 100,000 galaxies in a thin ribbon of the sky.
The Keyhole Nebula in Infrared
About three million years ago, the stars in the Keyhole Nebula began to form. The above picture of the Keyhole Nebula, also known as the Carina Nebula or NGC 3372, shows in infrared light many facets of this dramatic stellar nursery which lies only 9,000 light-years away.
A Bubbling Galaxy Center
What's happening in the center of this galaxy? Close inspection of the center of NGC 4438, as visible in this recently released representative-color image by the Hubble Space Telescope, reveals an unusual bubble of hot gas, colored in red.
Sirius: The Brightest Star in the Night
Sirius is the brightest star in the night sky. Sirius is visible on the far left of the above photograph, to the left of the constellation of Orion and Comet Hale-Bopp. Intrinsically, Sirius is over 20 times brighter than our Sun and over twice as massive.