Categorized | Featured, Sci-Tech

Eta Aquarids meteor shower and a super moon (May 5)

Size difference for the moon during her closest approach (perigee) and farthest passing (apogee). The diameter of the moon during perigee is 14 percent larger. (Photo courtesy of NASA)

Gerrit van der Plas | Special to Hawaii 24/7

If you like stargazing, Saturday (May 5) will make you twice as happy. Early Saturday morning between 4 a.m. and sunrise is your best chance to see the Eta Aquarids meteor shower. That same evening will treat you to a so-called supermoon.

The Supermoon

Because the moon orbits the earth in an elliptical orbit, the distance of the moon varies between 222,000 and 252,000 miles. Every instance (approximately once per month) when the moon reaches its closest distance to the earth is called a “perigee.” If this perigee happens during a full moon, it is called a supermoon.

Supermoons don’t occur every year. The last five happened in 1993, 2005, 2008, 2010 and 2011, and the next supermoon will be in 2016.

During a supermoon, the full moon will look about 14 percent larger and 30 percent brighter. If you have binoculars you should aim them at the moon and start exploring its surface with the help of this map:

You can find the Sea of Rain, the Sea of Tranquility and the Sea of Clouds!

Unfortunately in Hawaii you will just miss the peak of the supermoon. The moon is largest (reaches perigee) at 5:36 p.m., but only rises at 7 p.m. above the Hawaiian horizon. These few hours however don’t make that much of a difference, especially since the moon looks larger if it stands close to the horizon because of an optical illusion called the “moon illusion.”

Eta Aquarids meteor shower

This year’s Eta Aquarids meteor shower will be mostly outshone by the (almost) full moon. The constellation Aquarius (the radiant of this meteor shower) rises at 2 a.m. over the eastern horizon, but because of the bright (almost) full moon you will be able to see very few shooting stars.

Your best chance is to wait for early in the morning when the moon has almost set, between 4 a.m. and 5 a.m. Look toward the East and find the constellation Aquarius. This is where you will see most shooting stars.

Eta Aquarids Trivia

Did you know that the Eta Aquarids have a sister? The Eta Aquarids meteor shower happens when earth passes through the space-debris left by Halley’s Comet. There is another point in space where earth crosses the rubble from Halley’s Comet, and when this happens, we see the meteor shower the Orionids (and not the Delta Aquarids as people often think).

Halley’s Comet is the most famous short period comet of our solar system, and returns every 75 or 76 years. The last time it flew by was in 1986, the next time will be in 2061.

Right now Halley’s Comet is deep in the outer solar system (beyond Neptune!) but you will still be able to see little particles of it burn up into earths atmosphere twice a year during the Eta Aquarids and the Orionids meteor showers.

Each time it swings by the sun, solar heat vaporizes about 6(!) meters of ice and rock from the nucleus. The debris particles, about the size of sand grains, spread along the comet’s orbit, filling it with tiny meteoroids.

— Find out more:

(Gerrit van der Plas is a frequent visitor to the Big Island and writes for, which promotes sustainable tourism and has a special focus on astronomical events on Hawaii.)

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