SPACE: WHERE ARE WE GOING? : SUNGLINT

Sunday, August 4, 2013

NASA SHOWS ISS VIEW OF LAKE SUPERIOR

FROM: NASA
Gravity Waves and Sunglint, Lake Superior

From the vantage point of the International Space Station, astronauts frequently observe atmospheric and surface phenomena in ways that are impossible to view from the ground. Two such phenomena—gravity waves and sunglint—are illustrated in this photograph of northeastern Lake Superior. At the top of the image, the Canadian Shield of southern Ontario is covered by an extensive forest canopy typical of early summer. Offshore and to the west and southwest of Pukaskwa National Park, several distinct sets of parallel cloud bands are visible. Gravity waves are produced when moisture-laden air encounters imbalances in air density, such as might be expected when cool air flows over warmer air. This can cause the flowing air to oscillate up and down as it moves, causing clouds to condense as the air rises and cools and to evaporate away as the air sinks and warms. This produces parallel bands of clouds oriented perpendicular to the wind direction. The orientation of the cloud bands in this image, parallel to the coastlines, suggests that air flowing off of the land surfaces to the north is interacting with moist, stable air over the lake surface, creating gravity waves. The second phenomenon—sunglint—affects the water surface around and to the northeast of Isle Royale. Sunglint is caused by light reflection off a water surface; some of the reflected light travels directly back towards the observer, resulting in a bright mirror-like appearance over large expanses of water. Water currents and changes in surface tension—typically caused by presence of oils or surfactants—alter the reflective properties of the water and can be highlighted by sunglint. For example, surface water currents are visible to the east of Isle Royale that are oriented similarly to the gravity waves, suggesting that they too are the product of winds moving off of the land surface. Astronaut photograph ISS036-E-11843 was acquired on June 24, 2013, with a Nikon D3S digital camera using a 50 millimeter lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 36 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Image Credit: NASA Caption: William L. Stefanov (Jacobs/JETS) and Michael H. Trenchard (Barrios/JETS), NASA Johnson Space Center

STAR FLASH

What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon's outer surface suddenly greatly expanded with the result that it became the brightest star in the entire Milky Way Galaxy in January 2002. Then, just as suddenly, it faded. A stellar flash like this had never been seen before -- supernovas and novas expel matter out into space. Although the V838 Mon flash appears to expel material into space, what is seen in the above image from the Hubble Space Telescope is actually an outwardly moving light echo of the bright flash. In a light echo, light from the flash is reflected by successively more distant rings in the complex array of ambient interstellar dust that already surrounded the star. V838 Mon lies about 20,000 light years away toward the constellation of the unicorn (Monoceros), while the light echo above spans about six light years in diameter. Image Credit: NASA, ESA

THE SPIDERWEB GALAXY

Looking like a spider's web swirled into a spiral, Galaxy IC 342 presents its delicate pattern of dust in this image from NASA's Spitzer Space Telescope. Seen in infrared light, faint starlight gives way to the glowing bright patterns of dust found throughout the galaxy's disk. At a distance of about 10 million light-years, IC 342 is relatively close by galactic standards, however our vantage point places it directly behind the disk of our own Milky Way. The intervening dust makes it difficult to see in visible light, but infrared light penetrates this veil easily. IC 342 belongs to the same group as its even more obscured galactic neighbor, Maffei 2. IC 342 is nearly face-on to our view, giving a clear, top-down view of the structure of its disk. It has a low surface brightness compared to other spirals, indicating a lower density of stars (seen here as a blue haze). Its dust structures show up much more vividly (red). Blue dots are stars closer to us, in our own Milky Way. New stars are forming in the disk at a healthy rate. The very center glows especially brightly in the infrared, highlighting an enormous burst of star formation occurring in this tiny region. To either side of the center, a small bar of dust and gas is helping to fuel this central star formation. Data from Spitzer's infrared array camera are shown in blue (3.6 microns), green (4.5 microns) and red (5.8 and 8.0 microns). Image Credit: NASA/JPL-Caltech

JUMPING TO WARP SPEED

This cockpit view of a hypothetical spacecraft traveling at eight-tenths the speed of light shows the visual distortions that would be experienced at such high speeds. The star field is actually being wrapped toward the front of the craft in addition to being significantly blue-shifted. NASA Glenn leads the Breakthrough Propulsion Physics Project, NASA's primary effort to produce near-term, credible, and measurable progress toward the technology breakthroughs needed to revolutionize space travel and enable interstellar voyages. NASA Lewis (now Glenn) Research Center, Cleveland, Ohio.

OBSERVATION FROM THE SPACE STATION