Perseid meteor shower peaks August 11/12

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Posted: August 10, 2016

By Rick Nowell

The College of the Rockies’ meteor camera is already seeing more bright meteors zipping overhead.

The Perseid meteor shower started July 17 and ends August 24 but peaks on Thursday night, August 11 and Friday morning Aug 12. If it’s cloudy Thursday, note that Wednesday night (tonight) and Friday night will also be very active.

This year the Earth will cross the centre of the comet debris; so we should get the full show. We should also get three additional early peaks: Jupiter’s gravity has shifted some debris; and we’ll see debris from the 1862 and 1479 comet ejection trails to hit this year. Peak estimates (by Esko Lyytinen and Mikhail Maslov) are 150 to 160 meteors per hour; about three per minute.

There are four peaks in two waves; we’ll miss the first wave since it hits Thursday in daylight; and the last wave, which hits in Friday’s morning light. But the whole night should be pretty constant at 100 meteors/hour.

Best seeing times in the East Kootenay would be after midnight once the Moon sets (low in Scorpius) and the skies darken; continuing until dawn at 5 a.m. We’ll miss the last wave at 7 a.m. But these peak times are estimates; we can hope they arrive during darkness instead.

1) Thursday, Aug. 11 at 4:34 p.m. (Mountain Daylight Savings Time) [1862 comet trail];

2) Aug. 11 at 5:24 p.m. [1479 comet trail];

3) Aug. 11 from 6 to 10 p.m. [Jupiter shifts];

4) Friday morning, Aug. 12 from 7 to 9 a.m. [Centre of main comet orbit].

It takes the Earth a week to pass through all the ice and dust from comet Swift-Tuttle. The shower will gradually taper off and end by Aug. 24. The meteors are travelling at a speed of 59 km/s when they enter the Earth’s atmosphere. Their trails will all point to Perseus (if it’s a Perseid). The closer they are to Perseus, the smaller their trail; and the further away, the longer the trail.

Look for their colours—at high speed they ionize the air to a green; then that fades to yellow, orange, red as it slows down. If they disrupt and flare, you may see green/bluish wide streaks that glow afterward for a second or two (mainly it’s water ice, but there may be metals present like copper or cobalt).

Where to look? The composite photos above shows the entire sky, and all the meteors that fell on 11 and 12 Aug 2015 over Cranbrook; taken by our college meteor camera. Perseus is the constellation to the north east (middle left side of the photos right).

Normally there are fewer meteors seen straight overhead, since there is less volume of atmosphere overhead. There are slightly more meteors seen high to the west around Hercules and above the handle of the big dipper; since the meteor trails are longer there, and the meteors skim lower in a greater volume of atmosphere. That’s where I aim my cameras. (Or where it’s darkest, away from the Moon or city streetlight glow).

Some of the meteors seen will be from the k-Cygnids running from August 6–19. These peak on August 18 at three meteors per hour. They show a number of slow falling fireballs moving at 25km/second.

The lead image shows a k-Cygnid meteor crossing through Cygnus the Swan as seen during the last Perseid shower of 2015 (it’s tail is short and it points from Cygnus). Photo taken with a Nikon D100, Tamron 28mm f/2.5 lens, 30 second exposure. I outlined Cygnus in yellow against the Milky Way. The bright star Deneb is the tail at top, and Albireo is the beak at bottom. Photo credit: Rick Nowell.

While you’re out stargazing, here is a star map showing the Perseus region of the sky, looking northeast late after midnight in August. The Milky Way band (grey in the map) runs through Perseus; who is the Greek hero coming to rescue Andromeda (daughter of Cassiopeia) who is chained to the rocks. Look below the W of Cassiopeia (the Queen of Ethiopia). You should also see the great square of Pegasus, the winged horse to the right. If you have good eyes (or binoculars), you can spot the fuzzy cloud of the Andromeda Galaxy (M31 in the Map) just above Andromeda’s stick-figure knee. (Andromeda’s head is one corner of the square of Pegasus.) The big dipper, little dipper and Polaris are easy to locate to the left. (Star map generated by Skyglobe software).