Rare Planet Alignment Gives Way to Perseid Meteor Shower

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The annual Perseid meteor shower is already putting on an excellent show, and the celestial fireworks have yet to peak. The main event is tonight. Meanwhile, a delightfully tight configuration of planets graces the evening sky. The Perseids are bits of debris from Comet Swift-Tuttle, which has laid down several streams of debris, each in a slightly different location, over the centuries as it orbits the sun. 

Every August, Earth passes through these debris streams, which spread out over time. Most meteors are the size of sand grains, with a few as large as a pea. They vaporize as they enter Earth's atmosphere, creating brilliant streaks across the sky.

Meanwhile, Venus, Mars and Saturn are clustered in the evening sky and will be joined tonight and Friday by the graceful crescent moon. Anyone with clear skies can easily spot the foursome looming above the western horizon as soon as darkness falls. It's a great opportunity, using SPACE.com's planet alignment map, to find and identify planets you otherwise might mistake for stars. 

But wait, there's more. In the predawn all week, Jupiter is a brilliant jewel high in the southern sky and impossible to miss — nothing nearby is even close to being as bright.

While the planets and our moon are all very far apart in space, they appear lined up this week thanks to a special circumstance of orbital mechanics. The outer planets, Mars and Saturn, take much longer to go around the sun than the inner planet Venus. Venus "laps" the outer planets frequently, and it never strays far from the sun from our vantage point. 

Right now, as we look off into space in the evening, we're seeing Venus off to one side of the sun, and Mars and Saturn behind it and well beyond the sun.