Tonight – May 4, 2017 – the forecast calls for meteors! The greatest number of Eta Aquarid meteors will be lighting up the predawn darkness – as seen from all parts of Earth – over the next few mornings. No matter where you are, watch before dawn on May 5 and 6. Although the bright waxing gibbous moon will light up most of the night, the moon will set before the prime time viewing hours for the predawn Eta Aquariid 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 sets at an earlier hour on May 5 than it does on 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.
Under ideal conditions, the Eta Aquariid meteor shower produces up to 20 to 40 meteors per hour. The shower is best seen in the Southern Hemisphere, but mid-northern latitudes might catch some meteors, too. In the Northern Hemisphere, tropical and subtropical latitudes are favored, including latitudes like that of the southern U.S. North of 40o north latitude the meteors tend to be fewer. 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.
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.
Again, you don’t need to know the shower’s radiant point to watch the meteors!
Bottom line: In 2017, the Eta Aquarid meteor produces the most meteors before dawn on May 5 and 6. May 7 before dawn might be good as well. This is a great shower for the Southern Hemisphere! But mid-northern latitudes might still enjoy a decent sprinkling of meteors, and the moon will be out of the way during the dark hour before dawn. In a dark sky, you might catch as many as 20 to 40 per hour at southerly latitudes. Have fun!