Look Up! A Pre-Dawn Meteor Shower Arrives for Cinco de Mayo

By David W Brown |

The Milky Way, three airplanes, and at least four Eta Aquarid meteors soar over Utah's Bryce Canyon on May 6, 2014 in this digital panorama created from 12 smaller images. Image credit: © David Lane

Ways to celebrate Cinco de Mayo: Learn a little about Mexican history and the significance of the holiday. Drop in for the 2-for-1 margaritas at a local Mexican place and go for some authentic cuisine. Watch stars rain down from the sky in the best meteor shower this month—and if you live in the Southern Hemisphere, the best meteor shower of the year.

In the predawn hours of May 5 and 6, the Eta Aquarid meteor shower will reach its peak, with a possible 10–20 meteors visible per hour in the Northern Hemisphere, and about twice as many in the Southern Hemisphere, assuming clear skies and a minimum of light pollution.

So what are the Eta Aquarids, and where did they come from?

THE REMNANTS OF HALLEY'S COMET

The Eta Aquarid shower appears to originate in Eta Aquarii, a relatively bright star in the constellation Aquarius. (If you're in the Northern Hemisphere, look to the southeast before dawn.) Fear not, however: The meteors are not warning shots fired from an angry, far-off race of Eta Aquariians. Rather, what you are seeing when you see an Eta Aquarid meteor is a tiny, centuries-old remnant of Halley's Comet, seen below in close-up.

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Image credit: ESA/Max Planck Institute for Solar System Research

As comet Halley goes about its highly elliptical orbit around the Sun, it leaves behind dust and rock particles. It's been doing this for millennia, and when Earth's orbit intersects this ancient trail, the particles slam into our atmosphere at tens of thousands of miles per hour. The streaks of light you see are the result of the energy produced as the particles are vaporized.

GOOD NEWS! THE MOON WILL COOPERATE

When it comes to the night sky, if you're not fighting light pollution from below, you're fighting natural light from above. A full moon can wash the sky with a kind of ambient light, and drown out the bright streaks of meteors. In addition, a full, luminous moon can make it hard for your eyes to adjust to the darkness. (This might have made last month's Lyrid meteor shower a bit of a bust.)

Good news for the Cinco de Mayo shower, however: Only the barest sliver of the Moon will be visible, and May 6 will feature a new moon, which means the Moon will not be visible at all in the sky! So get out of the city and get thee to wherever your local astronomy club recommends. The best time to see the shower will be two hours before dawn. Give yourself a good hour for your eyes to adjust, bring a blanket, and wait. The cosmos will deliver.