Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Perseus. That is why the last week's meteor shower was known as the Perseids -- the meteors all appear to come from a radiant toward Perseus . Three dimensionally, however, sand-sized debris expelled from Comet Swift-Tuttle follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the Perseus. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Perseus. Pictured above , a composite image of this year's Pereids meteor shower shows many bright meteor s that streaked through the sky on August 12. To the surprise of many, the next night, August 13, also showed many meteors , as demonstrated by rolling one's cursor over the above image. This year's Leonids meteor shower in November is expected by some to be exceptionally active, perhaps producing as many as 500 meteors per hour.

Why are these people shooting a powerful laser into the center of our Galaxy? Fortunately, this is not meant to be the first step in a Galactic war . Rather, astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere . Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring . This information is fed back to a VLT telescope mirror which is then slightly deformed to minimize this blurring. In this case , a VLT was observing our Galaxy's center , and so Earth's atmospheric blurring in that direction was needed. As for inter-galaxy warfare , when viewed from our Galaxy's center , no casualties are expected. In fact, the light from this powerful laser would combine with light from our Sun to together appear only as bright as a faint and distant star.

Dark skies are favored for viewing meteor showers. But the annual Perseid Meteor Shower still entertained skygazers around the world this week even though the Moon brightened the night. At its last quarter phase and rising around midnight on August 13, after the shower's anticipated peak, the Moon is seen here above rock formations in the Alborz Mountains near Firouzkooh, Iran. With a dramatic desert landscape in the foreground, a Perseid meteor is streaking through the moonlit sky between the overexposed Moon and bright planet Jupiter at the upper right. A regular celestial event in the northern hemisphere, the Perseid Meteor Shower is caused by planet Earth's yearly passage through the dust stream cast off by comet Swift-Tuttle .

This early morning skyscape was captured last week on August 4th, looking northeast across calm waters in the Turn Basin at NASA's Kennedy Space Center. In a striking contrast in motion, the space shuttle Discovery , mounted on a massive transporter, creeps toward launch pad 39A at less than two miles per hour, while a brilliant meteor streaks through the sky traveling many miles per second. Of course, this week skywatchers have seen many similar meteor streaks during the annual Perseid meteor shower . But the meteor flashing above Discovery is not likely to be one of the Perseids because its path doesn't point back to that shower's radiant . Seen here near picture center, brilliant planet Venus still dominates the sky as the Morning Star , though. Yellowish tinted Mars lies near the top of the frame and Orion's red giant star Betelgeuse is toward the right.

What is this strange rock on Mars? Sitting on a smooth plane, the rock stands out for its isolation, odd shape, large size and unusual texture. The rock was discovered by the robotic Opportunity rover rolling across Mars late last month. Pictured above , Opportunity prepares to inspect the unusual rock. After being X-rayed, poked, and chemically analyzed , the rock has now been identified by Opportunity as a fallen meteorite. Now dubbed Block Island , the meteorite has been measured to be about 2/3 of a meter across and is now known to be composed mostly of nickel and iron . This is the second meteorite found by a martian rover, and so far the largest. Vast smooth spaces on Mars and Earth can make large meteorites stand out. Opportunity continues its trip across Meridiani Planum on Mars and is on schedule to reach expansive Endeavor Crater next year.

Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and is a well known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant and is a member of the Sculptor Galaxy Group . Classified as an irregular galaxy , in deep exposures the LMC itself resembles a barred disk galaxy. However, spanning about 50,000 light-years, NGC 55 is seen nearly edge-on, presenting a flattened, narrow profile in contrast with our face-on view of the LMC. Just as large star forming regions create emission nebulae in the LMC, NGC 55 is also seen to be producing new stars. This higly detailed galaxy portrait highlights a bright core crossed with dust clouds, telltale pinkish star forming regions, and young blue star clusters in NGC 55.

What happens when a meteor hits the ground? Usually nothing much, as most meteors are small, and indentations they make are soon eroded away. About 50,000 years ago, however, a large meteor created Barringer Meteor Crater in Arizona , USA . Also known simply as Meteor Crater, the resulting impact basin spans over a kilometer. Pictured above, a tour group views the inside of Barringer Crater early last year. In 1920, Barringer Crater was the first feature on Earth to be recognized as an impact crater . Today, over 100 terrestrial impact features have been identified over planet Earth. Computer modeling indicates that some of the Canyon Diablo impactor melted during the impact that created Barringer.

What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal , while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon . Iapetus also has an unusual equatorial ridge that makes it appear like a walnut . To help better understand this seemingly painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. Pictured above , from about 75,000 kilometers out, Cassini's trajectory allowed unprecedented imaging of the hemisphere of Iapetus that is always trailing . A huge impact crater seen in the south spans a tremendous 450 kilometers and appears superposed on an older crater of similar size. The dark material is seen increasingly coating the easternmost part of Iapetus , darkening craters and highlands alike. Close inspection indicates that the dark coating typically faces the moon's equator and is less than a meter thick. A leading hypothesis is that the dark material is mostly dirt leftover when relatively warm but dirty ice sublimates . An initial coating of dark material may have been effectively painted on by the accretion of meteor-liberated debris from other moons. This and other images from Cassini's Iapetus flyby are being studied for even greater clues.

Cloudy skies over Wuhan, China hid the delicate solar corona during July's total eclipse of the Sun . Still, the Moon's silhouette was highlighted by these glistening diamonds as the total eclipse phase ended. Caused by bright sunlight streaming through dips and valleys in the irregular terrain along the Moon's edge, the effect is known as Baily's Beads , named after Francis Baily who called attention to the phenomenon in 1836. The dramatic appearance of the beads at the beginning or end of a total solar eclipse is also known as the Diamond Ring effect. In this remarkable image, a small, pinkish solar prominence can also be seen along the edge, below the diamonds.

Like grains of sand on a cosmic beach, individual stars of barred spiral galaxy NGC 1313 are resolved in this sharp composite from the Hubble Space Telescope's Advanced Camera for Surveys ( ACS ). The inner region of the galaxy is pictured , spanning about 10,000 light-years. Hubble's unique ability to distinguish individual stars in the 14 million light-year distant galaxy has been used to unravel the fate of star clusters whose bright young stars are spread through the disk of the galaxy as the clusters dissolve . The exploration of stars and clusters in external galaxy NGC 1313 offers clues to star formation and star cluster evolution in our own Milky Way.