December 1, 2009--Stars sparkle against a rosy haze in a new closeup picture of the Iris nebula taken with the Hubble Space Telescope.
Although some nebulae are hot enough to generate their own light, cooler nebulae--including Iris--are visible because they scatter and reflect light from nearby stars. These so-called reflection nebulae usually appear blue, but an as yet unidentified chemical gives parts of the Iris nebula a reddish hue.
Image courtesy NASA & ESA
Paraguay's Shrinking Forests
November 26, 2009--A new high-resolution map based on data from NASA's Landsat 5 and Landsat 7 satellites shows how forest cover changed (light blue) in Paraguay between 1990 and 2000. The part of the map seen above highlights the rectangular fields and narrow roads that are altering forests around the Mbaracayú Nature Reserve.
The map is part of a forest-change analysis that shows that Paraguay lost 13 percent of its forests to agriculture and other human activity between 1990 and 2000. Most of the loss has been in the Atlantic forests--tropical woodlands distinct from Amazon rain forest--east of the Río Paraguay, including those around Mbaracayú.
Image courtesy NASA Earth Observatory, Robert Simmon
Black Hole Feeding Galaxy
November 30, 2009--A jet of high-energy particles shooting from a black hole (left) ignites stars in a nearby galaxy in an artist's rendering. Two new studies based on data from the European Southern Observatory suggest that the nearby active black hole HE0450-2958 is creating its future home by "zapping" a nearby galaxy, triggering rapid star formation.
Most large galaxies are thought to have supermassive black holes in their middles, although scientists haven't been sure which comes first, the galaxy or the black hole. HE0450-2958 has no identified host galaxy of its own. But the black hole's jet is feeding a companion galaxy, which is forming stars at a rate of about 350 suns a year--a hundred times the rate of a typical galaxy. Astronomers think the two objects will eventually merge, creating a full-fledged galaxy with a black hole at its heart.
Image courtesy ESO/L. Calcada
December 1, 2009--Like ships plowing through water, the British-controlled South Sandwich Islands create V-shaped "wakes" in clouds over the Atlantic Ocean, seen in a recent picture taken by NASA's Terra satellite.
As winds flow around and over each island, the air forms waves that get cooler at the peaks and warmer in the troughs, causing clouds to form at the peaks but not the troughs—hence the curved holes in the cloud cover seen above.
Image courtesy Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC
Terzan 5 Star Cluster
November 25, 2009--An unusual cluster of stars dubbed Terzan 5, seen above in a newly released picture, is likely a primordial protogalaxy that long ago merged with the Milky Way, say astronomers using the Very Large Telescope at the European Southern Observatory.
The "unfinished" dwarf galaxy is now part of what's known as the Milky Way's galactic bulge, a dense region of stars and gas surrounding the galaxy's center.