Eta Aquariids Meteor Shower to Peak Early May—What You Need to Know

A meteor shoots across the sky. Shutterstock/Sofoklo

Look closely at this predawn springtime scene: shooting stars sputtering over a southerly horizon on a dark, moonless night in early May.

This picture of shooting stars appears annually when the Eta Aquariid meteor shower—literally the cosmic dust shed by Halley’s Comet—collides with Earth as it orbits the sun. The Eta Aquariids’ peak period doesn’t always coincide with moonless nights, but fortunately for meteor viewers, this year’s will.

For early risers wanting to glimpse the Eta Aquariids before sunrise, or make a wish upon them, here are the basic facts you'll need.

When, Where, How to View Eta Aquariids

Although the Eta Aquariids will crop up roughly between April 15 and May 27 this year, their peak period, which is the best time for viewing, is a much narrower window on or around May 5. This matches when Earth hits that debris stream from Halley’s Comet, which loops far beyond our solar system, causing meteors when the debris burns up in our atmosphere.

Since the Eta Aquariids radiate from constellation Aquarius the Water Bearer, located in the Southern Hemisphere of the sky’s dome, they naturally favour observers south of the equator. The point from which meteors seem to radiate is called the radiant, but it’s preferable not to look to the radiant to find meteors (more on that later).

This radiant aligns almost exactly with the faint star Eta Aquarii, one of four stars comprising the Y-shaped “water jar” asterism in constellation Aquarius—which, if it’s not obvious by now, bequeathed the meteor shower its name: Eta Aquariids.

A star chart shows the constellation Aquarius and the Eta Aquariids' radiant near the faint star Eta Aquarii. Designed by The Epoch Times

Viewing meteors demands dark skies, and since the first quarter moon falls on May 4, a dark and moonless night will accompany the Eta Aquariids’ peak period. In general, meteor viewers should also avoid artificial city lights for the best viewing experience.

According to EarthSky, under optimal dark conditions with no moon, an observer in southern parts of the United States may sight 10 to 20 Eta Aquariids per hour.

What is the Radiant?

It might seem perplexing how for eons all these meteors could be traced to a single radiant point in the constellation Aquarius. But the Eta Aquariids don’t actually originate from there and travel all the way here; it’s just a trick of perspective that makes it seem so.

Those bits of ice and space rock amid the debris stream ignite about 100 kilometres above the Earth. So why do they seem to radiate from a point near Eta Aquarii, a star 170 light years—trillions of kilometres—away?

Moving in a vast orbit around the sun, the Eta Aquariids follow in the wake of their parent object, Halley’s Comet. Flying in orbit, the pieces of debris travel along parallel vectors. We may therefore apply the technique made famous by the artist-scientist Leonardo da Vinci, the rule of one-point perspective, when we view these objects flying in from outer space.

Similar to how train tracks travel in parallel and seem to converge as they travel toward the horizon, but never really converge, shooting stars, likewise, seem to converge at their radiant. But they don’t actually come from that distant star.

Meteors will not be found on or near the radiant, because they'll offer little profile. It’s best to catch sight of their elongated flanks as they whoosh by at wider angles, so take in the radiant’s periphery and view the entire sky.

However, since constellation Aquarius does favour the Southern Hemisphere, it’s better to face that general direction when observing the Eta Aquariids from north of the equator.

Where Do Eta Aquariids Originate?

All meteors begin their lives as either asteroids or comets (sometimes asteroids, which are basically space rocks, were comets that became extant). Many comets, which are like “dirty snowballs” of frozen gas and cosmic particles, orbit our sun but loop far beyond the solar system.

When comets near the sun, the sun’s energy causes them to sublimate and release gas and debris into space. Shedding their volatile matter, they leave vast complexes of material behind them. When Earth crosses paths with these debris streams, pieces burn up in our atmosphere and become meteors.

As regular as clockwork, Earth returns to that same stream and ploughs through as it follows its orbit, which is why we faithfully have had the Eta Aquariids and other meteor showers at roughly the same time of year for centuries.

Halley's Comet is photographed from Easter Island in 1986. NASA

Halley’s Comet, the Eta Aquariids’ parent object, orbits the sun every 76 years on average, and was observed as early as 240 B.C., according to EarthSky. The comet was last seen in the solar system in 1985–86 and reached its greatest distance away in 2023. It will return in 2061.

It’s believed that the English astronomer Edmond Halley was the first to grasp that Halley’s constant reappearances were actually of the same object. Speaking of firsts, Halley’s Comet also became the first comet to be studied by a spacecraft when the European Space Agency’s Giotto flew by and observed its surface.

The robotic spacecraft allowed scientists to study the structure of the comet’s icy nucleus. It also observed the gaseous envelope, or coma, that surrounds comets during sublimation and its signature comet tail, which both form in the heat of the sun.