the return of summer’s shooting star spectacular! – Astronomy Now

The annual Perseid meteor shower has been underway since last month and it predicted to reach its usual eagerly-anticipated maximum early next week, on 12 August between 13h and 16h UT. The Perseids is the year’s most popular meteor shower and one of the major highlights on the observing calendar, with many astronomical societies and keen individuals having made plans for trips to observe this special spectacle from a dark-sky site 

The Perseids are active from 17 July to 24 August, with cameras of the UK Meteor Network having already recorded activity. In particular, a dazzling Perseid fireball, estimated at magnitude –4.4, was just recently captured, on the night of 1/2 August at 01:19 UT (see image).

This year’s peak means your best chance to bag most meteors is on the night of 12/13 August (Monday night into Tuesday morning), though observed rates of meteors should still be good on the previous night, 11/12 August (Sunday night into Monday morning), and on 13/14 August. The Moon, too often it seems a blight by wiping out the chances of detecting fainter Perseids, is not a big factor this year. Its at waxing gibbous phase and sets at 11pm BST on 12 August. This leaves the field clear for meteor watches leading up to dawn as the radiant climbs ever higher in the east. 

Meteor showers have a peak called the ‘Zenithal Hourly Rate’ (ZHR). For the Perseids, the value is usually in the region of 100 (100–150 sometimes), though this hourly rate would only be seen if the showers radiant lay high overhead, at the zenith, and observing conditions were perfect. In the real observing world, from a reasonably good observing site when the radiant is high, hourly rates on average of around 40 meteors is not unreasonable. Assuming a cloudless and haze-free sky at a dark-sky site observers can expect to see between 50 and 70 meteors each hour near the peak.

The Perseid radiant lies in the far north of Perseus (see the graphic here showing you where it’s located), lying low in the north-eastern sky as darkness falls but climbing to a decent altitude of 50 degrees or so by 2am BST. By this time, the areas of the sky where Perseids are more likely to appear will be much better placed than prior to midnight. 

When on a meteor watch, don’t peer intently at the spot in the sky where the radiant lies. Perseid meteor trails or streaks here will appear short and therefore harder to see. You will see many more shooting stars if you observe an area of sky 30-40 degrees from the radiant (from where, meteor streaks may appear longer) and around 50 degrees above the horizon.

Perseid meteors are the result of debris from periodic comet 109P/Swift–Tuttle, shed along its 133-year orbit. They are swift, entering the Earth’s upper atmosphere at 60km/second. The shower is renowned for producing an abundance of bright meteors and fireballs that often leave lingering trails or trails.