The 2021 Eta Aquariid meteor shower reaches peak activity this week, on the morning of 6 May, and the best time to see it on peak night is at 02:30 BST (01:30 UT). Find out how to see an Eta Aquariid meteor tonight.
The Eta Aquariid meteor shower is visible from about 19 April to 28 May each year, and this week the Moon will be out of the way, giving meteor spotters in 2021 a good chance of seeing an Eta Aquariid streaking across the night sky.
On 6 May the meteor shower’s zenithal hourly rate (ZHR) should reach 55 meteors per hour, but the ZHR is really an estimate for comparative purposes between the annual meteor showers, and assumes perfectly dark conditions, no light pollution, no clouds and the radiant – the point from which the meteors appear to emanate – being directly overhead.
With a low altitude radiant, the number of Eta Aquariids you are likely to see should be lower, but it’s still a great opportunity to enjoy the warmer spring nights and do a bit of stargazing while meteor-watching.
For a fun activity to do at the same time, read our guide on how to star hop.
What is the Eta Aquariid meteor shower?
The Eta Aquariid meteor shower is one of many annual meteor showers that occur at the same time every year. Meteor showers are caused by Earth passing through streams of debris left behind by comets – and occasionally an asteroid, like for example asteroid 3200 Phaethon, which causes the Geminid meteor shower.
As Earth passes through the cosmic debris, particles enter the atmosphere at high speeds and they burn up, causing a bright streak to be seen in the sky. For more on this, read our guide What causes a meteor shower?
The Eta Aquariid meteor shower is one of two annual showers caused by Halley’s Comet, the second being the Orionid meteor shower which peaks in the third week of October.
Meteoroids from Halley’s Comet enter Earth’s atmosphere at a speed of 66km/s, putting them towards the upper part of the meteor speed spectrum.
How to see the Eta Aquariid meteor shower
The Eta Aquariid shower is best suited for the Southern Hemisphere sky, but it is certainly possible to see in the UK.
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.
The Moon will be kind to observers of the 2021 Eta Aquariids. 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.
Top tips for seeing an Eta Aquariid meteor
- Wrap up warm: it may be springtime, but meteor-observing involves lots of sitting still
- Find a dark spot away from light pollution
- Use a reclining chair or sun lounger to prevent neck-ache from looking upwards for extended periods
- Let your eyes get well and truly adjusted to the darkness for maximum sensitivity
- Locate the radiant
- Lean back and keep watching. If you see a bright steak emanating from the radiant, you’ve seen an Eta Aquariid
It is also advisable to observe with friends and family. This is much safer than standing in a remote location at night on your own, but also means you and the rest of your group can keep a record of how many meteors you spot.
Take turns to have one person note down the times that meteors are spotted, giving everyone else the chance to focus on observing.
If you do produce a record of how many Eta Aquariid meteors you saw, can could even submit your data to the British Astronomical Association Meteor Section.
Pete Lawrence is an expert astronomer, seasoned meteor observer and a co-host of The Sky at Night.