For older Image of the Day pictures, please visit the Image of the Day archives. Above: NGC 2467.
Monday, August 1, 2011: The first European antenna for the Atacama Large Millimeter/submillimeter Array (ALMA) crawls along a Chilean road on its way to the Chajnantor plateau, 5000 meters above sea level. Here, it joins antennas from the other international ALMA partners, bringing the total number to 16, meeting the minimum requirement to begin science observations. Soon, astronomers will begin conducting new scientific research with ALMA.
— Tom Chao
Tuesday, August 2, 2011: The crew of the International Space Station captured this image of sunglint on Cape Cod Bay, within the familiar "hook" of Cape Cod in Massachusetts, United States (center right). Sunlight reflecting off of a water surface directly towards the observer causes the phenomena of sunglint. Variations in the roughness of the water surface scatter the light, blurring the reflection and producing the silvery sheen of a sunglint area. To the left of Cape Cod in this image, the eastern end of Long Island, New York, is visible.
— Tom Chao
Wednesday, August 3, 2011: Not one, but two spiral galaxies make up NGC 3314. In the foreground, one galaxy appears face-on to us. The glow of the background galaxy brings out the dark swirls of interstellar dust in the foreground galaxy, a rare opportunity to explore the distribution of a galaxy's dust. NGC 3314 lies about 140 million light-years (background galaxy) and 117 million light-years (foreground galaxy) away in the multi-headed constellation Hydra.
— Tom Chao
Thursday, August 4, 2011: The Turn Basin at NASA's Kennedy Space Center provided the setting for this dramatic image of a meteor streaking down, seemingly in the direction of space shuttle Discovery. At the time, the orbiter was crawling slowly toward launch pad 39A on August 4, 2009. However, the meteor streaking across the sky was likely not what you might expect, a Perseid. Though it fell during that annual meteor shower, its sky trail doesn't point back at the Perseid meteor shower's radiant (point in the sky from which meteors appear to originate).
— Tom Chao
Friday, August 5, 2011: NASA's Juno spacecraft will carry a plaque dedicated to astronomer Galileo Galilei to Jupiter, with a scheduled launch date of August 5, 2011. The plaque, provided by the Italian Space Agency, measures 2.8 by 2 inches (71 by 51 millimeters), is made of flight-grade aluminum and weighs six grams (0.2 ounces). The plaque contains a self-portrait of Galileo and a passage he wrote in 1610 of observations of Jupiter. Galileo's text reads: "On the 11th it was in this formation – and the star closest to Jupiter was half the size than the other and very close to the other so that during the previous nights all of the three observed stars looked of the same dimension and among them equally afar; so that it is evident that around Jupiter there are three moving stars invisible till this time to everyone."
— Tom Chao
Monday, August 8, 2011: The diagonal, dark brown lines on the lighter-brown background in this image of Newton crater may provide evidence that liquid water currently flows on the surface of Mars. Comparison to other images of the same region taken over time by NASA's Mars Reconnaissance Orbiter show the lines (called recurring slope lineae) appearing. They gradually lengthen during warm seasons, and fade during cold seasons. Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.
— Tom Chao
Tuesday, August 9, 2011: A United Launch Alliance Atlas V rocket blasts off carrying NASA's Juno mission from Kennedy Space Center on August 5, 2011. The solar-powered spacecraft will research Jupiter's origins, structure, atmosphere and magnetosphere, and investigate the existence of a solid planetary core. The launch marks the second of five launches for NASA in 2011.
— Tom Chao
Wednesday, August 10, 2011: The Fine Ring Nebula seems to emanate from a binary star system. Observations suggest that the binary pair spins in a circle we see face-on from our vantage point, implying that the planetary nebula's structure aligns the same way. We are looking down on a torus (doughnut shape) of ejected material. Planetary nebulae form when some dying stars, after expanding into a red giant phase, expel a shell of gas as they evolve into white dwarfs. Most planetary nebulae are either spherical or elliptical in shape, or bipolar.
— Tom Chao
Thursday, August 11, 2011: Snow rarely falls in the Chilean Atacama Desert, where ESO's Very Large Telescope sits atop Cerro Paranal, a 8500-foot-high (2600-meter-high) mountain. The Atacama Desert is a very dry place with humidity often dropping below 10 percent and rainfall of less than 0.4 inches (10 millimeters) per year. This picture, taken shortly before sunrise, shows the landscape of the Atacama and the mountaintop domes of the VLT, and also the night sky. To the left of the VLT is a satellite trail, and to the right a meteor streaks through the sky.
— Tom Chao
Friday, August 12, 2011: Charles Messier designated the object pictured here 101 in his catalog of fuzzy things in the sky that are not comets. Known sometimes as the "Pinwheel Galaxy," Messier 101 is a grand design spiral galaxy, a disk of hundreds of billions of stars with a small central bulge and prominent arms spiraling out from the center. Messier 101 is very large: At nearly 200,000 light-years across it is about twice the size of our Milky Way Galaxy. Its high levels of star formation and very well-defined spiral arms are likely caused by gravitational interactions with neighboring galaxies.
— Tom Chao
Monday, August 15, 2011: Reflection nebula NGC 2023 lies nearly 1500 light-years from Earth. It lies within the constellation of Orion (The Hunter), close to the well-known Flame and Horsehead nebulas. NGC 2023 stretches a vast four light-years across. This picture only displays the southern part, with colors resembling a sunset on Earth. Stars are forming from the material comprising NGC 2023, and this Hubble image captures the billowing waves of gas, 5000 times denser than the interstellar medium.
— Tom Chao
Tuesday, August 16, 2011: Charles Messier discovered the Dumbbell Nebula, shown here, in 1764, and he added it as the 27th member of his well-known catalog of nebulous objects. Messier 27, as it is also known, became the first in a class of objects now known as planetary nebulae in the catalog. Planetary nebulae, named for their resemblance to gas-giant planets, consist of the remains of stars that once looked a lot like our sun.
— Tom Chao
Wednesday, August 17, 2011: Orion Multi-Purpose Crew Vehicle underwent its third water landing test at the Hydro Impact Basin located at NASA Langley Research Center during August 2011. The scenario shown here represented the worst-case scenario for landing. A prediction gave a 50% chance of the test article becoming inverted. The Orion Project Team collected valuable data regarding Crew Module stability, and also obtained invaluable experience in uprighting the test article.
— Tom Chao
Thursday, August 18, 2011: Stephen Colbert, host of The Colbert Report, welcomes the crew of space shuttle mission STS-135 while hilariously attired in a "space helmet." He also "planted" a flag reminscent of the Apollo 11 U.S. moon flag. The astronauts (seated counter-clockwise from lower left), Commander Chris Ferguson, Pilot Doug Hurley, Mission Specialists Sandy Magnus and Rex Walheim, were interviewed Tuesday evening, August 16, 2011, in New York City.
— Tom Chao
Friday, August 19, 2011: NASA hoists the twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft to the top of their launch pad at Space Launch Complex 17B at Cape Canaveral Air Force Station in Florida. The two mirror-image spacecraft will fly in tandem orbits around the moon for several months to measure its gravity field. GRAIL will seek to determine the structure of the lunar interior, from crust to core, and to advance understanding of the thermal evolution of the moon. Launch aboard a United Launch Alliance Delta II rocket is scheduled for Sept. 8.
— Tom Chao
Monday, August 22, 2011: The NASA/ESA Hubble Space Telescope has used its powerful optics to separate the globular cluster NGC 6401 into its constituent stars. NGC 6401 lies within the constellation of Ophiuchus (The Serpent Bearer). The globular cluster's faintness requires a telescope and some observational experience to see it. Globular clusters contain very rich, and generally spherical, collections of stars, hence the name. They orbit the cores of galaxies, with the force of gravity also keeping the stars bound as a group. There are around 160 globular clusters associated with our Milky Way, of which NGC 6401 is one. These objects are very old, containing some of the most ancient stars known. However, there are many mysteries surrounding them, with the origin of globular clusters and their role within galaxy evolution still not completely understood.
— Tom Chao
Tuesday, August 23, 2011: This pulsar, known as PSR J0357+3205 (or PSR J0357 for short), appears to have a long, bright X-ray tail streaming away from it. This composite image shows Chandra X-ray Observatory data in blue and Digitized Sky Survey data in yellow. The pulsar actually lies at the upper right end of the tail. The two bright sources near the lower left end of the tail are both thought to be unrelated background objects located outside our galaxy. Several unexplained characteristics of this tail suggest it is not entirely explained by the pulsar's existence.
— Tom Chao
Wednesday, August 24, 2011: NASA's Aqua satellite shows Tropical Storm Irene approaching Puerto Rico (left) on August 21, 2011 at 17:45 UTC (1:45 p.m. EDT). It since strengthened into a hurricane. At the time of this writing on Wednesday morning, August 24, 2011, the National Hurricane Center was reporting " ... IRENE BECOMES A CATEGORY THREE HURRICANE.... EYE HEADED FOR THE CROOKED AND ACKLINS ISLANDS ... "
— Tom Chao
Thursday, August 25, 2011: This infrared image from NASA’s Wide-field Infrared Survey Explorer (WISE), shows that some clouds are so cool and thick that even infrared can’t penetrate them. The clouds colored green, yellow and red are only seen in infrared. However, the black areas in this image — called infrared dark clouds (IRDCs) — are exceptionally cold, dense cloud cores seen in silhouette against the bright diffuse infrared glow of the plane of the Milky Way. The density in these clouds is high enough to lead to the formation of new stars and planets.
— Tom Chao
Friday, August 26, 2011: Something unexplained has warped barred spiral galaxy NGC 2146 so severely that an immense arm now lies directly in front of the center of the galaxy, as seen in this Hubble Space Telescope image. To pull this structure out of its natural shape and twist it up to 45 degrees would require colossal forces. Researchers surmise that a neighboring galaxy gravitationally perturbs it and distorts the orbits of many of NGC 2146's stars. This scenario may represent the end stages of a process occurring for tens of millions of years. NCG 2146 also undergoes intense bouts of star formation, to such an extent that astronomers refer to it as a starburst galaxy.
— Tom Chao
Monday, August 29, 2011: On Saturday, August 27, 2011, Astronaut Ron Garan pointed his HD camera at the rising sun as the International Space Station flew along a path between Rio de Janeiro in Brazil & Buenos Aires in Argentina. The choice of location was made by an online vote.
— Tom Chao
Tuesday, August 30, 2011: The Canada-France-Hawaii Telescope in Hawaii sees the barred spiral galaxy NGC 2903 almost face-on in this photograph. The central bulge glows yellow with older stars, while the spiral arms contain younger stars as determined by their blue color, and star formation regions of red.
— Tom Chao
Wednesday, August 31, 2011: The Mars Express High-Resolution Stereo Camera captured this image on 17 May 2010, showing a part of the northern polar region of Mars at the northern hemisphere summer solstice. At this point in the Martian year all of the carbon dioxide ice has warmed and evaporated into the planet’s atmosphere. Only water ice is left behind, which shows up as bright white areas in this picture. [Please click the image to see a larger version.]
— Tom Chao
