Look out for the Lyrids

The Lyrid radiant is well up in the eastern sky by 1am BST. AN graphic by Greg Smye-Rumsby.

Over the course of the next two nights the annual April Lyrid meteor shower is predicted to reach its 2021 peak. Given some precious clear spells it should be possible to spy a handful of Lyrids, seen as randomly occurring streaks of light across the night sky as tiny particles vaporise, burning up in Earth’s atmosphere. Lyrid meteors appear to emanate from the direction of Lyra’s brilliant star Vega, hence the name. The Lyrid’s return is especially welcome for meteor enthusiasts and casual stargazers alike, following the three-month-long drought of a major meteor shower since the Quadrantids at the start of the year.

When do I observe and what can I expect?

The April Lyrids have already been active for about a week or so and will persist until around the end of April, though observed rates on these peripheral nights are much lower than those seen at around the shower’s peak. In 2021, the Lyrids are forecast to reach maximum activity at around 13:00 UT (2pm BST) on 22 April. This timing is not ideal for UK observers, but your best bet is to head out on the nights of both 21/22 (Wednesday evening/Thursday morning) and 22/23 April (Thursday evening/Friday morning). The Lyrids can usually be relied upon to produces rates close to the shower’s maximum for a few nights centred around the peak.

The Lyrids are not one of the heavyweight meteor showers like August’s Perseids and December’s Geminids, so don’t expect dozens of meteor an hour to rain down. It is classed as a ‘medium-activity’ shower with a reliable quota of around 10 meteors an hour, which is in addition to the normal background rate of ‘sporadics’ – meteors it’s possible to see on any given moonless night. The Lyrids area known for producing bright meteors, and fireballs (intensely brilliant meteors) are not uncommon.

Lyrids are medium-speed meteors (~48 kilometres/sec [30 miles/sec]) and are produced from the debris stream of comet 1861 G1 (Thatcher), which last appeared in the inner Solar System at the time of its discovery. It’s not expected to return again until 2283.

Where do I look?

For all meteor showers, the point in the sky to which the meteors’ paths can be traced back is called the ‘radiant’. The Lyrid radiant is located close to the bright constellation of Lyra, the Lyre, around eight degrees south-west to the brilliant star Vega (alpha [α] Lyrae, magnitude +0.03); the radiant’s position at the shower’s maximum is RA 18h 07m, Dec +33.1°, which actually places it among the stars of eastern Hercules.

For your best chance of seeing meteors, try to shield yourself from having to look in the direction of any local lights and the Moon (obviously, the overall sky glow from light pollution is unavoidable at urban and suburban locations), and become dark adapted. Perhaps counterintuitively, don’t peer directly at the radiant but look in its general direction around 30 to 40 degrees to either side of it, and at an altitude of about 50 degrees.

Lyra and eastern Hercules are clear of the north-eastern horizon by 10pm BST on both nights, but you’ll benefit by concentrating your ‘watch’ (a meteor observing session is known as a ‘watch’) from around midnight until dawn. Before this time, some potential Lyrid activity will occur below the horizon, and by waiting until the radiant is higher in the sky you’ll see more shooting stars and it will be easier to track their paths across the sky to confirm whether it was a Lyrid or merely a sporadic.

By 1am BST, Vega lies at an elevation of over 40 degrees altitude in the east-north-east, and it is high overhead by 4.30am BST, by which time the night is drawing to a close.

Not the pesky Moon again!

Meteor showers can be adversely affected, or even completely wiped out by the presence of damaging Moon glow. Unfortunately, this year’s Lyrids will be marred by a waxing gibbous Moon in Leo. The strong glare from it will pervade the entire sky for most of the the night and affect the visibility of fainter Lyrids.

Despite the Moon menace, given some clear skies it will still be well worth venturing out into the crisp spring night to witness some shooting stars. Although meteor science is well advanced in the twenty-first century, like the much-improved weather forecasts of the present day one can be never be 100 per cent sure of observed meteor-rate predictions, much as those of fair weather or otherwise. Every now and then the Lyrids spring a surprise and rates well in excess of predictions have been experienced before, notably in 1982.