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NASA Satellite Captures Brightest Space Explosion Ever Recorded

The monster gamma ray burst happened only a quarter of the universe away, which scientists say makes it one of the best chances to observe a …

APOD: Galaxy Collisions: Simulation vs Observations (2013 May 14) Images Credit: NASA, ESA; Visualization: Frank Summers (STScI); Simulation: Chris Mihos (CWRU) & Lars Hernquist (Harvard). Explanation: What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide. Rather the gravitation of each galaxy will distort or destroy the other galaxy, and the galaxies may eventually merge to form a single larger galaxy. Expansive gas and dust clouds collide and trigger waves of star formation that complete even during the interaction process. Pictured above is a computer simulation of two large spiral galaxies colliding, interspersed with real still images taken by the Hubble Space Telescope. Our own Milky Way Galaxy has absorbed several smaller galaxies during its existence and is even projected to merge with the larger neighboring Andromeda galaxy in a few billion years. Starship Asterisk* • APOD Discussion Page Starship Asterisk* • On This Day in APOD

APOD: Four X-class Flares (2013 May 16) Image Credit: NASA, Solar Dynamics Observatory, GSFC Explanation: Swinging around the Sun's eastern limb on Monday, a group of sunspots labeled active region AR1748 has produced the first four X-class solar flares of 2013 in less than 48 hours. In time sequence clockwise from the top left, flashes from the four were captured in extreme ultraviolet images from the Solar Dynamics Observatory. Ranked according to their peak brightness in X-rays, X-class flares are the most powerful class and are frequently accompanied by coronal mass ejections (CMEs), massive clouds of high energy plasma launched into space. But CMEs from the first three flares were not Earth-directed, while one associated with the fourth flare may deliver a glancing blow to the Earth's magnetic field on May 18. Also causing temporary radio blackouts, AR1748 is likely not finished. Still forecast to have a significant chance of producing strong flares, the active region is rotating into more direct view across the Sun's nearside. Starship Asterisk* • APOD Discussion Page Starship Asterisk* • On This Day in APOD

APOD: Orion Nebula in Oxygen, Hydrogen, and Sulfur (2013 Jun 04) Image Credit & Copyright: César Blanco González Explanation: Few astronomical sights excite the imagination like the nearby stellar nursery known as the Orion Nebula. The Nebula's glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud. Many of the filamentary structures visible in the above image are actually shock waves - fronts where fast moving material encounters slow moving gas. The Orion Nebula spans about 40 light years and is located about 1500 light years away in the same spiral arm of our Galaxy as the Sun. The Great Nebula in Orion can be found with the unaided eye just below and to the left of the easily identifiable belt of three stars in the popular constellation Orion. The above image shows the nebula in three colors specifically emitted by hydrogen, oxygen, and sulfur gas. The whole Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years. Starship Asterisk* • APOD Discussion Page Starship Asterisk* • On This Day in APOD

APOD: Bright Planetary Nebula NGC 7027 from Hubble (2013 Aug 26) Image Credit: Hubble Legacy Archive, ESA, NASA; Processing: Delio Tolivia Cadrecha Explanation: It is one of the brightest planetary nebulae on the sky -- what should it be named? First discovered in 1878, nebula NGC 7027 can be seen toward the constellation of the Swan (Cygnus) with a standard backyard telescope. Partly because it appears there as only an indistinct spot, it is rarely referred to with a moniker. When imaged with the Earth-orbiting Hubble Space Telescope, however, great details are revealed. Studying Hubble images of NGC 7027 have led to the understanding that it is a planetary nebula that began expanding about 600 years ago, and that the cloud of gas and dust is unusually massive as it appears to contain about three times the mass of our Sun. Pictured above in assigned colors, the resolved, layered, and dust-laced features of NGC 7027 might remind sky enthusiasts of a familiar icon that could be the basis for an informal name. Please feel free to make suggestions -- some suggestions are being recorded, for example, in an online APOD discussion forum. Starship Asterisk* • APOD Discussion Page #APOD

APOD: M2-9: Wings of a Butterfly Nebula (2013 Sep 15) Credit: Hubble Legacy Archive, NASA, ESA - Processing: Judy Schmidt Explanation: Are stars better appreciated for their art after they die? Actually, stars usually create their most artistic displays as they die. In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes. The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousand of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto. The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance. Much remains unknown about the physical processes that cause planetary nebulae. Starship Asterisk* • APOD Discussion Page #APOD

APOD: M45: The Pleiades Star Cluster (2013 Sep 18) Credit & Copyright: Roberto Colombari Explanation: Have you ever seen the Pleiades star cluster? Even if you have, you probably have never seen it as dusty as this. Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen without binoculars from even the depths of a light-polluted city. With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident. The above exposure took about 20 minutes and covers a sky area several times the size of the full moon. Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus). A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six stars visible to the unaided eye. The actual number of Pleiades stars visible, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer's eyesight. Starship Asterisk* • APOD Discussion Page #APOD

APOD: Cometary Globules (2013 Oct 12) Image Credit & Copyright: Subaru Telescope (NAOJ) & DSS; Assembly and Processing: Robert Gendler Explanation: Bright-rimmed, flowing shapes gather near the center of this rich starfield toward the boarders of the nautical southern constellations Pupis and Vela. Composed of interstellar gas and dust, the grouping of light-year sized cometary globules is about 1300 light-years distant. Energetic ultraviolet light from nearby hot stars has molded the globules and ionized their bright rims. The globules also stream away from the Vela supernova remnant which may have influenced their swept-back shapes. Within them, cores of cold gas and dust are likely collapsing to form low mass stars, whose formation will ultimately cause the globules to disperse. In fact, cometary globule CG30 (upper right in the group) sports a small reddish glow near its head, a telltale sign of energetic jets from a star in the early stages of formation. Starship Asterisk* • APOD Discussion Page #APOD

APOD: NGC 891 Edge-on (2013 Oct 11) Image Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, Univ. of Arizona Explanation: This sharp cosmic portrait features NGC 891. The spiral galaxy spans about 100 thousand light-years and is seen almost exactly edge-on from our perspective. In fact, about 30 million light-years distant in the constellation Andromeda, NGC 891 looks a lot like our Milky Way. At first glance, it has a flat, thin, galactic disk and a central bulge cut along the middle by regions of dark obscuring dust. The combined image data also reveal the galaxy's young blue star clusters and telltale pinkish star forming regions. And remarkably apparent in NGC 891's edge-on presentation are filaments of dust that extend hundreds of light-years above and below the center line. The dust has likely been blown out of the disk by supernova explosions or intense star formation activity. Faint neighboring galaxies can also be seen near this galaxy's disk. Starship Asterisk* • APOD Discussion Page #APOD