August 12th, 2009 | 
Author: They were gawking at the annual Perseid meteor shower, which every year brings up to 100 meteors per hour blazing fiery streaks across the sky as the Earth passes through the dust trail of Comet Swift-Tuttle, said Mark Hammergren, an astronomer at Adler Planetarium.
The bright spectacle isn’t over yet. The meteor shower is expected to peak between 12:30 and 3 p.m. Wednesday but sky watchers only can see the meteors in the dark, Hammergren said. So sit tight until the sun sets, then look up. You could see up to one meteor a minute, Hammergren said. The show should continue for at least a week, he said.
Discovered in 1862, the comet is a giant iceberg made up of ice, rock and dust particles that likely has been in orbit for thousands of years, Hammergren said. Particles — about the size of a sesame seed when clustered together — slowly have been eroding from the comet every time it has approached the sun, leaving a trail of debris that the Earth’s orbit intersects once a year, Hammergren said.
The particles, known as meteoroids, create a meteor shower when they collide with the Earth’s atmosphere and burn up, forming fiery streaks across the sky.
A bright meteor glows as much as the brightest stars in the sky, Hammergren said. And pay close attention: They zip across the sky at about 132,000 m.p.h., leaving a gazer’s sight in a second or two, he said.
The best viewing place? Get away from the city lights and look northeast.
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This view of a rock called “Block Island,” the largest meteorite yet found on Mars, comes from the panoramic camera (Pancam) on NASA’s Mars Exploration Rover Opportunity.
This iron-nickel meteorite found near Fort Stockton, Texas, in 1952 shows a surface texture similar to some portions of the surface of an iron-nickel meteorite that NASA’s Mars Exploration Rover Opportunity found on Mars in July 2009.
NASA’s Mars Exploration Rover Opportunity used its microscopic imager to get this view of the surface of a rock called “Block Island” during the 1,963rd Martian day, or sol, of the rover’s mission on Mars (Aug. 1, 2009).