Eta Aquariid meteor shower
BEST TIME TO SEE: Morning of 6 May
The Eta Aquariid meteor shower reaches its peak on the morning of 6 May. On this date, the shower’s zenithal hourly rate (ZHR) should reach 55 meteors per hour, although with a low altitude radiant, the visual rate you actually see will be significantly lower.
This shower is one of two annual showers caused by Halley’s Comet, the second being the Orionid shower which peaks in the third week of October. The Eta Aquariid shower is best suited for Southern Hemisphere-viewing, but here in the UK it’s possible to catch a few trails from it.
The radiant (the point at which the shower appears to a terrestrial observer) is located near to the Water Jar asterism in the constellation of Aquarius, the Water Bearer. In early May, this region of sky rises around 02:40 BST (01:40 UT). The nights get short in May and the onset of dawn twilight means the viewing window for the Eta Aquariids is pretty short from the UK.
With a lot stacking up against this shower, at least 2021’s Moon is kind. New Moon occurs on 11 May, five days after the shower’s peak. Although the waning crescent Moon sits in the early morning sky near to the Water Jar, it’s significantly south of the radiant’s position, not rising until dawn has really brightened the sky.
The shower is typically active from 19 April until 28 May. Meteoroids from Halley’s Comet enter Earth’s atmosphere at the speed of 66km/s, putting them towards the upper part of the meteor speed spectrum.
As ever, the best strategy for observing Eta Aquariid meteors is to let your eyes get well and truly adjusted to the darkness for maximum sensitivity. Find somewhere comfortable to recline back on so you are looking up at the sky at an altitude around 60˚; any direction will do. Then all you have to do is wait and be patient.