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Eta Aquariids before dawn May 5

Tomorrow before dawn – May 5, 2018 – perhaps some of the brighter Eta Aquariid meteors can overcome the light of the bright waning gibbous moon to streak the predawn sky. This shower particularly favors the Southern Hemisphere. No matter where you are, the moon will be out in force during the prime time viewing hours of this predawn meteor shower.

It’s hard to say with certainty which morning will be the better of the two – May 5 or 6 – since this shower has a relatively broad peak. Possibly, May 5 could be the better morning to watch, because the moon will set at an earlier hour on the morning of May 5 than it will on the morning of May 6.

Just remember that – as seen from all parts of Earth – the dark hour before dawn typically presents the greatest number of Eta Aquarid meteors. The beginning of astronomical twilight closes the curtains on the final hour of complete darkness. Don’t know when the moon sets or astronomical twilight begins in your sky? Find out with this handy custom sunrise-sunset calendar.

Everything you need to know: Eta Aquarid meteor shower

EarthSky’s meteor shower guide for 2018

Eta Aquarids meteor shower from Atacama Desert thanks to our friend Yuri Beletsky!   Visit Yuri on Facebook.

View larger. | Yuri Beletsky caught these Eta Aquarids meteors from the Atacama Desert in 2015.

Under ideal conditions, the Eta Aquariid meteor shower produces up to 20 to 40 meteors per hour. If you’re in the Southern Hemisphere, and you have a very dark sky with no moon, you might see that many in a year when the moon is not in the sky. In the Northern Hemisphere, those living at subtropical and tropical latitudes have the advantage over their more northern counterparts.

North of about 40o north latitude the meteors tend to be few and far between. The reason has to do with the time of twilight and sunrise on the various parts of Earth. To learn more, check this post on why more Eta Aquarid meteors are visible in the Southern Hemisphere.

Eta Aquarid radiant

The radiant point for the Eta Aquarid meteor shower lies in front of the "Water Jar" asterism in the constellation Aquarius.

The point in the sky from which meteors in annual showers appear to radiate is called the radiant. You don’t have to locate the radiant to watch the Eta Aquariid meteors, but people often ask about them. Although the Eta Aquariid meteors streak all over the sky, they appear to radiate from the Y-shaped group of stars called the Water Jar. The Water Jar is part of the constellation Aquarius.

To star-hop to the Water Jar, first of all find the four stars of the Great Square of Pegasus. (See sky chart below.) Looking eastward at about 4 a.m. (Daylight Saving Time), the Great Square of Pegasus glitters like a celestial baseball diamond. Imagine the bottom star as home base. Draw a line from the third base star through the first base star, then go twice that distance to locate the star Sadal Melik.

To the lower left of Sadal Melik is the small Y-shaped Water Jar, marking the approximate radiant of the Eta Aquarid meteor shower.

Just remember, you don’t need to know the shower’s radiant point to watch the meteors!

Use the Great Square of Pegasus to star-hop to the radiant of the Eta Aquariid meteor shower.

Bottom line: In 2018, the Eta Aquarid meteor produces the most meteors before dawn on May 5 – but in the glare of the waning gibbous moon. This is a great shower for the Southern Hemisphere, so keep in mind the year 2019, when there will be no moon to ruin the annual Eta Aquariid meteor shower!

EarthSky’s meteor shower guide for 2018

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Bruce McClure