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May 2023 meteors … the Eta Aquariids

Moonlight will obscure the 2023 Eta Aquariids.

When to watch: Full moon falls near the peak of the 2023 Eta Aquariid shower. If you want to try watching in moonlight, try the mornings of May 5, 6 and 7, 2023, in the hours before dawn. Why before dawn? See Radiant chart above. The American Meteor Society is listing 15 UTC on May 6 as the shower’s predicted** peak time. But times vary between different experts. And the peak of this shower stretches out over several days. So you can expected elevated numbers of meteors a few days before and after the peak time … albeit in moonlight.
Nearest moon phase: In 2023, full moon will fall at 17:34 UTC on May 5. Moonlight will obscure the 2023 Eta Aquariids.
Radiant: Rises in the wee hours, climbing toward its highest point at dawn. That’s why before dawn is the best time to watch this shower.
Duration of shower: April 15 to May 27.
Expected meteors at peak, under ideal conditions: In the southern half of the U.S., you might see 10 to 20 meteors per hour under a dark sky, with no moon, when the radiant is high in the sky. Farther south – at latitudes in the Southern Hemisphere – you might see two to three times that number.
Note: The Eta Aquariids’ radiant is on the ecliptic, which rides low in the sky on spring mornings as seen from the Northern Hemisphere. That’s why this shower favors the Southern Hemisphere. It’s often that hemisphere’s best meteor shower of the year … but not in 2023, when moonlight will drown out most meteors.

Visit EarthSky’s meteor shower guide for 2023

Report a fireball (very bright meteor) to the American Meteor Society: it’s fun and easy!

The Eta Aquariids’ parent comet

This section is by the late, great Don Machholz (1952-2022), who discovered 12 comets …

The object responsible for the Eta Aquariid meteor shower – that is, its parent comet – is the famous Halley’s Comet. This comet is in a retrograde orbit around the sun. That means it runs around the sun in the opposite direction from Earth and all the other planets. As a result, we pass near its path twice, one time along the outbound portion of the comet’s orbit. That happens every early May, causing the Eta Aquariid meteor shower. The other time is along the inbound portion of the comet’s orbit, and that passage causes the Orionid meteor shower in late October of each year.

Halley’s Comet orbits the sun on an average of every 76 years (the range is from 74 through 79 years due to perturbations of the planets). So, in most years, the comet is nowhere near when we sweep through its orbit, and when debris left behind by the comet enters our atmosphere to create Halley’s two meteor showers.

Perhaps you saw Halley’s Comet when it returned last, in 1985/86. It has been observed since the year 240 BCE. Halley’s Comet will be back in 2061. Presently the comet is traveling away from the sun at about 0.6 miles a second (0.9 km/sec). In the year 2023, Halley’s Comet is beyond the orbit of Pluto.

In November or December of 2023, the comet will reach its farthest point from the sun that binds it in orbit. Then – pulled inexorably by the sun’s gravity – it will curve around and head back toward the inner solar system again.

While waiting for Halley’s Comet to return, watch for the next best thing: the Eta Aquariid meteor shower in early May.

More about this shower’s radiant

If you trace the paths of the Eta Aquariid meteors backward, they all seem to radiate from a certain point in front of the constellation Aquarius the Water Bearer. This point on the sky’s dome is called the radiant of the meteor shower, which nearly aligns with the faint star Eta Aquarii. Hence, this meteor shower gets its name from this star.

Eta Aquarii is one of the four stars making up the Y-shaped Water Jar asterism in the northern part of Aquarius. If you can find the Water Jar in the constellation Aquarius, you’ve as good as located the radiant point for the Eta Aquariid meteors. The alignment of the radiant and the star is, of course, coincidental. Eta Aquarii is some 170 light-years away – trillions upon trillions of miles away – while the Eta Aquariid meteors burn up nearby – only 60 miles (100 km) above Earth’s surface.

Meteor shower radiants are sometimes misunderstood by casual meteor-watchers. You don’t need to know where they are to watch a meteor shower. That’s because the meteors fly every which way across the sky, in front of numerous constellations. However, the higher a shower’s radiant appears in your sky, the more meteors you’re likely to see. For the Eta Aquariids, the radiant soars highest in the nighttime sky just before dawn. That’s one of the reasons why you can expect to see the most meteors in the wee morning hours.

How to view a meteor shower

As with all meteors in annual showers, no special equipment to watch the Eta Aquariids. But a little luck always helps.

Find a dark, open sky away from artificial lights, and sprawl out on a reclining lawn chair.

Make yourself comfortable with a hot flask of you favorite beverage. Keep warm but not so snug that you fall asleep!

Meteor watching is a lot like fishing. Sometimes you catch a good number of them, and sometimes you don’t.

Eta Aquariid meteor shower photos from EarthSky’s community

Bottom line: May’s Eta Aquariid meteor shower has a broad peak and often can be watched over several mornings. But, in 2023, moonlight interferes.

**Predicted peak times and dates for meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary. Back to top.

Read more: Why the Eta Aquariids are best from the Southern Hemisphere.

Meteor showers: Tips for watching the show

The next penumbral lunar eclipse: May 5-6, 2023

An eclipse of the moon can only happen at full moon, when the sun, Earth and moon line up in space, with Earth in the middle. So at such times, Earth’s shadow falls on the moon, creating a lunar eclipse. Lunar eclipses happen a minimum of two times to a maximum of five times a year. As a matter of fact, there are three kinds of lunar eclipses: total, partial and penumbral.

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The three types of lunar eclipses

In a total eclipse of the moon, the inner part of Earth’s shadow, called the umbra, falls on the moon’s face. Then at mid-eclipse, the entire moon is in shadow, which may appear blood red.

Next, there is a partial lunar eclipse, where the umbra takes a bite out of only a fraction of the moon. The dark bite grows larger, and then recedes, never reaching the total phase.

Finally, there’s a penumbral lunar eclipse, when only the more diffuse outer shadow of Earth – the penumbra – falls on the moon’s face. In fact, this third kind of lunar eclipse is much more subtle, and much more difficult to observe, than either a total or partial eclipse of the moon. That’s because there is never a dark bite taken out of the moon, as in a partial eclipse. So the eclipse never progresses to reach the dramatic minutes of totality. And at best, at mid-eclipse, very observant people will notice a dark shading on the moon’s face. Others will look and notice nothing at all.

According to eclipse expert Fred Espenak, about 35% of all eclipses are penumbral. Another 30% are partial eclipses, where it appears as if a dark bite has been taken out of the moon. And the final 35% go all the way to becoming total eclipses of the moon, a beautiful natural event.

What to expect from a penumbral eclipse

Some eclipse photos

Bottom line: There are three kinds of lunar eclipses: total, partial and penumbral. A penumbral eclipse is very subtle. At no time does a dark bite appear to be taken out of the moon. Instead, at mid-eclipse, observant people will notice a shading on the moon’s face.

Next penumbral lunar eclipse: May 5-6, 2023