Astronomy Picture Of the Day (APOD)Star Factory Messier 17
Sculpted by stellar winds and radiation, the star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this 1/3 degree wide field of view spans over 30 light-years.
The Fractured North Pole of Saturns Enceladus
The north pole of Saturn's moon Enceladus is unexpectedly fascinating and complex. Previous to the latest flyby of the robotic Cassini spacecraft, the northern region was known mostly for its unusually high abundance of craters.
When Black Holes Collide
What happens when two black holes collide? This extreme scenario likely occurs in the centers of some merging galaxies and multiple star systems. The featured video shows a computer animation of the final stages of such a merger, while highlighting the gravitational lensing effects that would appear on a background starfield.
The Southern Cross in a Southern Sky
Have you ever seen the Southern Cross? This famous constellation is best seen from Earth's Southern Hemisphere. Captured from Rio de Janeiro, Brazil, the four bright stars that mark the Southern Cross are visible just above the horizon in the featured image.
Mammatus Clouds Over Saskatchewan
Why is this cloud so bubbly? Normally, cloud bottoms are flat. The flatness is caused by moist warm air that rises and cools and so condenses into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms.
Bright Spiral Galaxy M81
One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81. The grand spiral galaxy can be found toward the northern constellation of the Great Bear (Ursa Major).
Night Hides the World
Stars come out as evening twilight fades in this serene skyscape following the Persian proverb "Night hides the world, but reveals a universe." The scene finds the Sun setting over northern Kenya and the night will soon hide the shores of Lake Turkana, home to many Nile crocodiles.
M16 and the Eagle Nebula
A star cluster around 2 million years young surrounded by natal clouds of dust and glowing gas, M16 is also known as The Eagle Nebula. This beautifully detailed image of the region includes cosmic sculptures made famous in Hubble Space Telescope close-ups of the starforming complex.
A Gegenschein Lunar Eclipse
Is there anything interesting to see in the direction opposite the Sun? One night last month, there were quite a few things. First, the red-glowing orb on the lower right of the featured image is the full moon, darkened and reddened because it has entered Earth's shadow.
The Elephants Trunk in IC 1396
Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Of course, the cosmic elephant's trunk is over 20 light-years long.