Astronomy Picture Of the Day (APOD)A Year of Resolving Cosmology
This year, humanity learned that the universe is 13.7 billion years old. Before this year, the universe's age was thought to be about 13 billion years, but really only constrained to be between about 12 billion and 15 billion years old.
A Dust Devil Crater on Mars
What caused the streaks in this Martian crater? Since the above image shows streaks occurring both inside and outside the crater, they were surely created after the crater-causing impact. Newly formed trails like these...
The Witch Head Nebula
Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion.
Trifid Pillars and Jets
Dust pillars are like interstellar mountains. They survive because they are more dense than their surroundings, but they are being slowly eroded away by a hostile environment. Visible in the above picture...
The Pleiades Star Cluster
Perhaps the most famous star cluster on the sky, the Pleiades can be seen without binoculars from even the depths of a light-polluted city. Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and closest open clusters.
Young Star, Dark Cloud
High-speed outflows of molecular gas from a young stellar object glow in infrared light, revealing themselves in this recent false-color image from the Spitzer Space Telescope. Cataloged as HH (Herbig-Haro) 46/47 the infrared source...
Venus and the 37 Hour Moon
At Table Mountain Observatory, near Wrightwood California, USA on October 26, wild fires were approaching from the east. But looking toward the west just after sunset, astronomer James Young could still enjoy this comforting view of a young crescent Moon and brilliant Venus through the the fading twilight. Setting over the horizon of Mt.
Layered Hills on Mars
Why are some hills on Mars so layered? The answer is still under investigation. Clearly, dark windblown sand surrounds outcropping of light sedimentary rock across the floor of crater Arabia Terra. The light rock clearly appears structured into many layers, the lowest of which is likely very old.
Comet Encke Returns
It's back. Every 3.3 years, Comet Encke swoops back into our inner Solar System. First officially discovered in 1786, Comet Encke is on its 59 th documented return, making it one of the best-studied comets on the sky.
The Andromeda Galaxy from GALEX
Why does the Andromeda Galaxy have a giant ring? Viewed in ultraviolet light, the closet major galaxy to our Milky Way Galaxy looks more like a ring galaxy than a spiral. The ring...