The show begins at sundown, August 12, when Venus, Saturn, Mars and the crescent Moon pop out of the western twilight in tight conjunction. All four heavenly objects will fit within a circle about 10 degrees in diameter, beaming together through the dusky colors of sunset. No telescope is required to enjoy this naked-eye event.
The planets will hang together in the western sky until 10 pm or so. When they leave, following the sun below the horizon, you should stay, because that is when the Perseid meteor shower begins. From 10 pm until dawn, meteors will flit across the starry sky in a display that’s even more exciting than a planetary get-together.
The Perseid meteor shower is caused by debris from Comet Swift-Tuttle. Every 133 years the huge comet swings through the inner solar system and leaves behind a trail of dust and gravel. When Earth passes through the debris, specks of comet-stuff hit the atmosphere at 140,000 mph and disintegrate in flashes of light. These meteors are called Perseids because they fly out of the constellation Perseus.
For best results, get away from city lights. The darkness of the countryside multiplies the visible meteor rate 3- to 10-fold. A good dark sky will even improve the planetary alignment, allowing faint Mars and Saturn to make their full contribution to the display. Many families plan camping trips to coincide with the Perseids. The Milky Way arching over a mountain campground provides the perfect backdrop for a meteor shower.
Link to the NASA Explorer Schools Virtual Campus home page.
Rocks examined by NASA’s Mars rover Spirit hold evidence of an ancient wet, non-acidic environment that may have been favorable for life. Confirming this mineral clue took four years of analysis by several scientists.
Spirit inspected many rock outcrops, including one called Comanche by scientists. They discovered magnesium iron carbonate makes up about one-fourth of the measured volume in Comanche samples. That is a tenfold higher concentration than any previously identified for carbonate in a Martian rock.
Massive carbonate deposits on Mars have been sought for years without much success. Numerous channels apparently carved by flows of liquid water on ancient Mars suggest the planet was formerly warmer, thanks to greenhouse warming from a thicker atmosphere than exists now. The dense, ancient Martian atmosphere was probably rich in carbon dioxide, because that gas makes up nearly all the very thin, modern atmosphere.
Finding a tick usually involves a squeamish self-examination — carefully rubbing fingertips through your scalp, meticulously scanning your body, and groaning “eyeww” if a little bloodsucker is discovered. But now there is a new way to discover these pesky, disease-laden critters — via satellite!
Two University of Alabama at Birmingham graduate students are pioneering the new technique as part of a NASA program called DEVELOP. They’ve been using satellite images of Alabama’s Talladega National Forest to reveal likely areas of the forest where ticks may flourish. The students used what they learned from their NASA advisor, Dr. Jeff Luvall of NASA’s Marshall Space Flight Center in Huntsville, to classify levels of vegetation and moisture in 12 locations in the forest. They then created detailed digital maps and images showing likely tick habitats — areas where dense vegetation overlapped those with high soil moisture.