<p><strong>The annual Perseid meteor shower, which peaks this week, is dazzling sky-watchers around the world.</strong></p><p dir="ltr">Here, a bright fireball is caught lighting up the starry skies above Teutonia Peak in the Mojave National Preserve in California on August 10, more than a day before the official maximum activity peak for the Perseid meteors. (<a href="http://newswatch.nationalgeographic.com/2013/08/11/tips-for-enjoying-the-perseid-meteor-shower/">Read more on enjoying the Perseid meteor shower</a>.)</p><p dir="ltr">Considered the most visually stunning meteor shower of 2013, the Perseids peak every August, when the Earth slams into a giant cloud of debris left behind by comet Swift-Tuttle along its orbit.</p><p dir="ltr">While most meteors zipping across the skies are no bigger than a grain of sand, fireballs like the one pictured above can be anywhere from the size of a grapefruit to the size of a basketball. The resulting high-speed impact causes unusually bright meteors, which astronomers call bolides, which can cast shadows and even a lingering smoke trail.</p><p dir="ltr"><em>—Andrew Fazekas</em></p>