The Flash Spectrum of the Sun

Explanation: In a flash, the visible spectrum of the Sun changed from absorption to emission on November 3rd, during the brief total phase of a solar eclipse. That fleeting moment is captured by telephoto lens and diffraction grating in this well-timed image from clearing skies over Gabon in equatorial Africa. With overwhelming light from the Sun's disk blocked by the Moon, the normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images at each wavelength of light emitted by atoms along the thin arc of the solar chromosphere. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

Aurora and unusual Clouds Over Iceland

Explanation: What's happening in the sky? On this cold winter night in Iceland, quite a lot. First, in the foreground, lies the largest glacier in Iceland: Vatnajokull. On the far left, bright green auroras appear to emanate from the glacier as if it was a volcano. Aurora light is reflected by the foreground lake Jökulsárlón. On the far right is a long and unusual lenticular cloud tinged with green light emitted from another aurora well behind it. Just above this lenticular cloud are unusual iridescent lenticular clouds displaying a broad spectral range of colors. Far beyond the lenticular is the setting Moon, while far beyond even the Moon are setting stars.

 The above image was captured in late March of 2012.

the Magnificent Trail Of Comet Mc Naught

Explanation: Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing tail showed its greatest extent on long-duration, wide-angle camera exposures. During some times, just the tail itself estimated to attain a peak brightness of magnitude -5 (minus five), was caught by the comet's discoverer in the above image just after sunset in January 2007 from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, then faded as it moved further into southern skies and away from the Sun and Earth. Within the next two weeks of 2013, rapidly brightening Comet ISON might sprout a tail that rivals even Comet McNaught.

Hubble Catches a Spiral in the Air Pump

Lying more than 110 million light-years away from Earth in the constellation of Antlia (The Air Pump) is the spiral galaxy IC 2560, shown here in an image from NASA/ESA Hubble Space Telescope. At this distance it is a relatively nearby spiral galaxy, and is part of the Antlia cluster — a group of over 200 galaxies held together by gravity. This cluster is unusual; unlike most other galaxy clusters, it appears to have no dominant galaxy within it.

In this image, it is easy to spot IC 2560's spiral arms and barred structure. This spiral is what astronomers call a Seyfert-2 galaxy, a kind of spiral galaxy characterized by an extremely bright nucleus and very strong emission lines from certain elements — hydrogen, helium, nitrogen, and oxygen. The bright center of the galaxy is thought to be caused by the ejection of huge amounts of super-hot gas from the region around a central black hole.

There is a story behind the naming of this quirky constellation — Antlia was originally named antlia pneumatica by French astronomer Abbé Nicolas Louis de Lacaille, in honor of the invention of the air pump in the 17th century.

Calm Skies Over Three Oceans

We live on a dynamic, restless planet. On any given day, there is usually a cyclone, tropical depression, or extra-tropical storm brewing somewhere on the Earth. But for a brief moment this week, the skies over all of the oceans were relatively calm.

The image above is a composite of fourteen polar satellite passes, or swaths, stitched together from September 8, 2013. The natural-color images were acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite.

At the time of those near-midday passes, there were no hurricanes, cyclones, or tropical storms in the Atlantic, Pacific, or Indian Ocean basins—a relatively rare occurrence at the height of the hurricane/cyclone season in the northern hemisphere. There was plenty of cloud cover, of course, and smaller storm systems. In the eastern Pacific, remnants of tropical storm Lorena were breaking up near the Baja Peninsula. In the eastern Atlantic, the pieces of tropical depression #9 were starting to gather near the islands of Cape Verde; by the next day, tropical storm Humberto would form.

In its May and August 2013 outlooks, the National Hurricane Center forecasted a 70 percent chance of a “more active than normal” season, with 13 to 20 named storms and 7 to 11 hurricanes. A “normal” season typically produces 12 named storms, including 6 hurricanes. Through the second week of September (the midpoint of the Atlantic hurricane season), there have been nine named storms—keeping pace with predictions—but just one that reached hurricane strength.

The one hurricane, Humberto, was observed on September 11, 2013, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. Humberto became a hurricane around 5 a.m. on September 11, just hours short of becoming the latest date for the first hurricane in a season. By September 13, Humberto had weakened to a tropical storm. Forecasts were calling for the northwest-moving storm to reach hurricane status again by September 19, when it will be in the middle of the Atlantic Ocean and well away from land.The slow start does not necessarily mean the hurricane season will be mild. “What happens in the early part of the season is generally not a good predictor of the second half of the season, which is when the majority of hurricanes and major hurricanes form,” said Gerry Bell, lead seasonal hurricane forecaster for the National Oceanic and Atmospheric Administration. “NOAA’s outlooks are for the season as a whole, and not for any particular month during the season.”

In the period from 1981 to 2010, the Atlantic basin has averaged six hurricanes per year, and 61 percent of all Atlantic named storms form from September through November. “The 2013 hurricane season was billed as a stud, but up through mid-September, it has been a dud,” said Bill Patzert, climatologist at NASA’s Jet Propulsion Laboratory. “Stay vigilant, though. Hurricanes could be late and active. Remember hurricane Sandy in late October last year.”

Solar Filament Eruption Creats

A magnetic filament of solar material erupted on the sun in late September, breaking the quiet conditions in a spectacular fashion. The 200,000 mile long filament ripped through the sun's atmosphere, the corona, leaving behind what looks like a canyon of fire. The glowing canyon traces the channel where magnetic fields held the filament aloft before the explosion. In reality, the sun is not made of fire, but of something called plasma: particles so hot that their electrons have boiled off, creating a charged gas that is interwoven with magnetic fields.

NGC 6946: The 'Fireworks Galaxy'

NGC 6946 is a medium-sized, face-on spiral galaxy about 22 million light years away from Earth. In the past century, eight supernovas have been observed to explode in the arms of this galaxy. Chandra observations (purple) have, in fact, revealed three of the oldest supernovas ever detected in X-rays, giving more credence to its nickname of the "Fireworks Galaxy." This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan.

Image credit: X-ray: NASA/CXC/MSSL/R.Soria et al, Optical: AURA/Gemini OBs

Hubble catches Stellar Explosions in NGC6984

Supernovae are intensely bright objects. They are formed when a star reaches the end of its life with a dramatic explosion, expelling most of its material out into space. The subject of this new Hubble image, spiral galaxy NGC 6984, played host to one of these explosions back in 2012, known as SN 2012im. Now, another star has exploded, forming supernova SN 2013ek — visible in this image as the prominent, star-like bright object just slightly above and to the right of the galaxy's center.

SN 2012im is known as a Type Ic supernova, while the more recent SN 2013ek is a Type Ib. Both of these types are caused by the core collapse of massive stars that have shed — or lost — their outer layers of hydrogen. Type Ic supernovae are thought to have lost more of their outer envelope than Type Ib, including a layer of helium.

The observations that make up this new image were taken on August 19,  2013, and aimed to pinpoint the location of this new explosion more precisely. It is so close to where SN 2012im was spotted that the two events are thought to be linked; the chance of two completely independent supernovae so close together and of the same class exploding within one year of one another is a very unlikely event. It was initially suggested that SN 2013ek may in fact be SN 2012im flaring up again, but further observations support the idea that they are separate supernovae — although they may be closely related in some as-yet-unknown way