Which moon is this? Earth's. Our Moon's unfamiliar appearance is due partly to an unfamiliar viewing angle as captured by a little-known spacecraft -- the Soviet Union's Zond 8 that circled the Moon in October of 1970. Pictured above, the dark-centered circular feature that stands out near the top of the image is Mare Orientale, a massive impact basin formed by an ancient collision with an asteroid. Mare Orientale is surrounded by light colored and highly textured highlands. Across the image bottom lies the dark and expansive Oceanus Procellarum, the largest of the dark (but dry) maria that dominate the side of the Moon that always faces toward the Earth. Originally designed to carry humans, robotic Zond 8 came within 1000 km of the lunar surface, took about 100 detailed photographs on film, and returned them safely to Earth within a week. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)
Which moon is this? Earth's. Our Moon's unfamiliar appearance is due partly to an unfamiliar viewing angle as captured by a little-known spacecraft -- the Soviet Union's Zond 8 that circled the Moon in October of 1970. Pictured above, the dark-centered circular feature that stands out near the top of the image is Mare Orientale, a massive impact basin formed by an ancient collision with an asteroid. Mare Orientale is surrounded by light colored and highly textured highlands. Across the image bottom lies the dark and expansive Oceanus Procellarum, the largest of the dark (but dry) maria that dominate the side of the Moon that always faces toward the Earth. Originally designed to carry humans, robotic Zond 8 came within 1000 km of the lunar surface, took about 100 detailed photographs on film, and returned them safely to Earth within a week. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)
What's going on in the center of this spiral galaxy? Named the Sombrero Galaxy for its hat-like resemblance, M104 features a prominent dust lane and a bright halo of stars and globular clusters. Reasons for the Sombrero's hat-like appearance include an unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge visible in the above image from the 200-inch Hale Telescope. Close inspection of the central bulge shows many points of light that are actually globular clusters. M104's spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand. The very center of the Sombrero glows across the electromagnetic spectrum, and is thought to house a large black hole. Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo. Astrophysicists: Browse 600+ codes in the Astrophysics Source Code Library
What lights up this castle of star formation? The familiar Eagle Nebula glows bright in many colors at once. The above image is a composite of three of these glowing gas colors. Pillars of dark dust nicely outline some of the denser towers of star formation. Energetic light from young massive stars causes the gas to glow and effectively boils away part of the dust and gas from its birth pillar. Many of these stars will explode after several million years, returning most of their elements back to the nebula which formed them. This process is forming an open cluster of stars known as M16. Random APOD: Click here to surf the universe
Reddened rays of the setting Sun flooded the skies over Cedar Creek Lake, southeast of Dallas, Texas, planet Earth on July 6th. And while sunsets may be the most watched celestial event, this one even offered something extra. A sunspot so large it was visible to the naked eye is captured in the serene sunset view, near the center of a solar disk dimmed and distorted by Earth's dense atomosphere. Telescopic views revealed the spot to be a complex of large solar active regions composed of sunspots, some larger than planet Earth itself.
This fifteen degree wide field of view stretches across the crowded starfields of Sagittarius toward the center of our Milky Way galaxy. In fact, the center of the galaxy lies near the right edge of the rich starscape and eleven bright star clusters and nebulae fall near the center of the frame. All eleven are numbered entries in the catalog compiled by 18th century cosmic tourist Charles Messier. Gaining celebrity status with skygazers, M8 (Lagoon), M16 (Eagle), M17 (Omega), and M20 (Trifid) show off the telltale reddish hues of emission nebulae associated with star forming regions. But also eye-catching in small telescopes are star clusters in the crowded region; M18, M21, M22, M23, M25, and M28. Broader in extent than the star clusters themselves, M24 is actually a cloud of the Milky Way's stars thousands of light-years long, seen through a break in the galaxy's veil of obscuring dust. You can put your cursor over the image (or click here) for help identifying Messier's eleven.
This complex of dusty nebulae linger along the edge of the Taurus molecular cloud, a mere 450 light-years distant. Stars are forming on the cosmic scene, including extremely youthful star RY Tauri prominent toward the upper left of the 1.5 degree wide telescopic field. In fact RY Tauri is a pre-main sequence star, embedded in its natal cloud of gas and dust, also cataloged as reflection nebula vdB 27. Highly variable, the star is still relatively cool and in the late phases of gravitational collapse. It will soon become a stable, low mass, main sequence star, a stage of stellar evolution achieved by our Sun some 4.5 billion years ago. Another pre-main sequence star, V1023 Tauri, can be spotted below and right, embedded in its yellowish dust cloud adjacent to the striking blue reflection nebula Ced 30.
One of the largest sunspot regions in recent years is now crossing the Sun. This region of convoluted magnetic fields may well produce a solar flare that releases a cloud of energetic particles into the Solar System. Were a very powerful cloud to impact the Earth's magnetosphere, it could be dangerous to Earth-orbiting astronauts and satellites. Conversely, the impact of even a less energetic cloud might create picturesque aurora. Pictured above is the sunspot region as it appeared two days ago. The rightmost part of this region has been cataloged as AR 11785, while the left part as AR 11787. The darkest sunspot regions contain nearly vertical magnetic fields and are called umbras, while the surrounding bronze regions -- more clearly showing stringy magnetic flux tubes -- are called penumbras. Churning solar granules, many about 1000 km across, compose the yellow background region. No one knows what this sunspot region will do, but space weather researchers are monitoring it closely. Random APOD: Click here to surf the universe
Supergiant star Gamma Cygni lies at the center of the Northern Cross, a famous asterism in the constellation of the Swan (Cygnus). Known by the proper name Sadr, the bright star also lies at the center of this gorgeous skyscape, featuring a complex of stars, dust clouds, and glowing nebulae along the plane of our Milky Way galaxy. The field of view spans over 3 degrees (six Full Moons) on the sky and includes emission nebula IC 1318 and open star cluster NGC 6910. Left of Gamma Cygni and shaped like two glowing cosmic wings divided by a long dark dust lane, IC 1318's popular name is understandably the Butterfly Nebula. Above and slightly left of Gamma Cygni, are the young, still tightly grouped stars of NGC 6910. Some distance estimates for Gamma Cygni place it at around 1800 light-years while estimates for IC 1318 and NGC 6910 range from 2,000 to 5,000 light-years.
Pluto's newly discovered moons now have names. Known previously as P4 and P5, the International Astronomical Union has now given the fourth and fifth discovered moons of Pluto the names Kerberos and Styx. The small moons were discovered in 2011 and 2012 by the Hubble Space Telescope in preparation for the close passing of the New Horizons spacecraft by Pluto in 2015. Kerberos is named for the many headed dog in Greek mythology that guards the entrance to the underworld, while Styx is named for the goddess who overlooks the mythological river that runs between the Earth and the underworld. Both monikers are related to the name of Pluto, who rules the mythical nether region. Because their reflectivity is unknown, the size of each moon is quite uncertain -- but each is crudely estimated to be about 20 kilometers in diameter. The robotic New Horizons spacecraft is on schedule to pass by Pluto in 2015 and provide the first clear images of the dwarf planet and its companions.
In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines at the upper left. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a compact red emission region, and streamers of obscuring dust against a backdrop of stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured here are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation of the Unicorn (Monoceros). The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be about 15 light-years across. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)
The universe is filled with galaxies. But to see them astronomers must look out beyond the stars of our own galaxy, the Milky Way. This colorful Hubble Space Telescopic portrait features spiral galaxy NGC 6384, about 80 million light-years away in the direction of the constellation Ophiuchus. At that distance, NGC 6384 spans an estimated 150,000 light-years, while the Hubble close-up of the galaxy's central region is about 70,000 light-years wide. The sharp image shows details in the distant galaxy's blue star clusters and dust lanes along magnificent spiral arms, and a bright core dominated by yellowish starlight. Still, the individual stars seen in the picture are all in the relatively close foreground, well within our own galaxy. The brighter Milky Way stars show noticeable crosses, or diffraction spikes, caused by the telescope itself.
Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster NGC 6752 roams the halo of our Milky Way galaxy. Over 10 billion years old, NGC 6752 follows clusters Omega Centauri and 47 Tucanae as the third brightest globular in planet Earth's night sky. It holds over 100 thousand stars in a sphere about 100 light-years in diameter. Telescopic explorations of the NGC 6752 have found that a remarkable fraction of the stars near the cluster's core, are multiple star systems. They also reveal the presence of blue straggle stars, stars which appear to be too young and massive to exist in a cluster whose stars are all expected to be at least twice as old as the Sun. The blue stragglers are thought to be formed by star mergers and collisions in the dense stellar environment at the cluster's core. This sharp color composite also features the cluster's ancient red giant stars in yellowish hues.