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Showing posts from March, 2018

Flying over the Earth at Night II

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What would it be like to orbit the Earth? The International Space Station (ISS) does this every 90 minutes, and sometimes the astronauts on board take image sequences that are made into videos. The featured time-lapse video shows many visual spectacles of the dark Earth below. First, as the video begins, green and red auroras are visible on the upper left above white clouds. Soon city lights come into view, and it becomes clear you are flying over North America, eventually passing over Florida. In the second sequence you fly over Europe and Africa, eventually passing over the Nile River. Brief flashes of light are lightning in storms. Stars far in the distance can be seen rising through the greenish-gold glow of the Earth's atmosphere. via NASA http://ift.tt/2HrQDTJ

Horsehead: A Wider View

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Combined image data from the massive, ground-based VISTA telescope and the Hubble Space Telescope was used to create this wide perspective of the interstellar landscape surrounding the famous Horsehead Nebula. Captured at near-infrared wavelengths, the region's dusty molecular cloud sprawls across the scene that covers an angle about two-thirds the size of the Full Moon on the sky. Left to right the frame spans just over 10 light-years at the Horsehead's estimated distance of 1,600 light-years. Also known as Barnard 33, the still recognizable Horsehead Nebula stands at the upper right, the near-infrared glow of a dusty pillar topped with newborn stars. Below and left, the bright reflection nebula NGC 2023 is itself the illuminated environs of a hot young star. Obscuring clouds below the base of the Horsehead and on the outskirts of NGC 2023 show the tell-tale far red emission of energetic jets, known as Herbig-Haro objects, also associated with newborn stars. via NASA http://i…

Cyclones at Jupiter s North Pole

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Juno's Jovian Infrared Auroral Mapper data was used to construct this stunning view of cyclones at Jupiter's North Pole. Measuring the thermal emission from Jovian cloud tops, the infrared the observations are not restricted to the hemisphere illuminated by sunlight. They reveal eight cyclonic features that surround a cyclone about 4,000 kilometers in diameter, just offset from the giant planet's geographic North Pole. Similar data show a cyclone at the Jovian South Pole with five circumpolar cyclones. The South Pole cyclones are slightly larger than their northern cousins. Cassini data has shown that gas giant Saturn's north and south poles each have a single cyclonic storm system. via NASA http://ift.tt/2Fq3HIN

Colorful Airglow Bands Surround Milky Way

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Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in calm water. Red airglow likely originates from OH molecules about 87-kilometers high, excited by ultraviolet light from the Sun, while orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. While driving near Keluke Lake in Qinghai Provence in China, the photographer originally noticed mainly the impressive central band of the Milky Way Galaxy. Stopping to photograph it, surprisingly, the resulting sensitive camera image showed airglow bands to be quite prominent and span the entire sky. The featured image has been digitally enhanced to make the colors more vibrant. via NASA http://ift.tt/2FhJXqI

Clouds, Birds, Moon, Venus

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Sometimes the sky above can become quite a show. In early September of 2010, for example, the Moon and Venus converged, creating quite a sight by itself for sky enthusiasts around the globe. From some locations, though, the sky was even more picturesque. In the featured image taken in Spain, a crescent Moon and the planet Venus, on the far right, were captured during sunset posing against a deep blue sky. In the foreground, dark storm clouds loom across the image bottom, while a white anvil cloud shape appears above. Black specks dot the frame, caused by a flock of birds taking flight. Very soon after this picture was taken, however, the birds passed by, the storm ended, and Venus and the Moon set. Bright Venus is again visible just after sunset this month (2018 March) and will appear quite near Mercury tonight and the rest of this week. via NASA http://ift.tt/2F7vb9Y

Southwest Mare Fecunditatis

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Frank Borman, James Lovell, and William Anders journeyed from Earth to the Moon and back again in December of 1968. From lunar orbit, their view of craters in southwest Mare Fecunditatis is featured in this stereo anaglyph, best experienced from armchairs on planet Earth with red/blue glasses. Goclenius is the large impact crater in the foreground. About 70 kilometers (45 miles) in diameter its lava-flooded floor is scarred by rilles or grooves, long, narrow depressions in the surface. Crossing the crater walls and central peaks the rilles were likely formed after the crater itself. In the background, the two large craters with smooth floors are Colombo A (top) and Magelhaens. Magelhaens A, the background crater with the irregular floor, is about 35 kilometers (20 miles) in diameter. via NASA http://ift.tt/2oMkChI

The Lunar X

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The striking X in this lunarscape is easily visible in binoculars or a small telescope, but not too many have seen it. The catch is, this lunar X is fleeting and only apparent in the hours before the Moon's first quarter phase. Along the shadow line between lunar day and night, the X illusion is produced by a configuration of craters seen here toward the left, Blanchinus, La Caille and Purbach. Near the Moon's first quarter phase, an astronaut standing close to the craters' position would see the slowly rising Sun very near the horizon. Temporarily, crater walls would be in sunlight while crater floors would still be in darkness. Seen from planet Earth, contrasting sections of bright walls against the dark floors by chance look remarkably like an X. This sharp image of the Lunar X was captured on February 22nd. For extra credit, sweep your gaze along the lunar terminator and you can also spot the Lunar V. via NASA http://ift.tt/2HSh71Q