Get Ready for the 2016 Perseids

perseid meteor

Out camping under the August sky? The coming week gives us a good reason to stay up late, as the Perseid meteor shower graces the summer sky. An ‘old faithful’ of annual meteor showers, the Perseids are always sure to produce.

The 2016 Perseids present a few challenges, though persistent observers should still see a descent show. The Perseids are typically active from July 17th to August 24th, with the peak arriving this year right around 13:00 to 15:30 Universal Time on Friday, August 12th. This will place the radiant for the Perseids high in the sky after local midnight for observers in the northern Pacific, though observers worldwide should be vigilant over the next week. Meteor showers don’t read predictions and prognostications, and an arrival of the peak just a few hours early would place North America in the cross-hairs this coming Friday. The Perseids typically produce an average Zenithal Hourly Rate of 60-200 per hour, and the International Meteor Organization predicts a ZHR of 150 for 2016.

Looking to the northeast from latitude 50 degrees north at 1AM local on the morning of August 12th. Image credit: Stellarium.
Looking to the northeast from latitude 50 degrees north at 1AM local on the morning of August 12th. Image credit: Stellarium.

The nemesis of the 2016 is the Moon, which reaches Full on August 18th, six days after the shower’s peak. The time to start watching this shower is now, before the waxing Moon becomes a factor. The farther north you are, the earlier the Moon sets this week:

Moonset on the evening of August 11/12th:

Latitude versus Moonset ( in local daylight saving time)

20 degrees north – 1:30 AM

30 degrees north – 1:14 AM

40 degrees north – 0:56 AM

50 degrees north – 0:30 AM

Early morning is almost always the best time to watch any meteor shower, as the Earth-bound observer faces in to the meteor stream head on. The December Geminids only recently surpassed the Perseids in annual intensity in the past few years.

The orientation of the Earth's shadow versus, the Sun, Moon and the radiant of the Perseids at the start of the projected peak on August 12th. Image credit: Orbitron.
The orientation of the Earth’s shadow versus the Sun, Moon and the radiant of the Perseids at the start of the projected peak on August 12th. Image credit: Orbitron.

The radiant of the Perseids drifts through the constellations of Cassiopeia, Perseus and Camelopardalis from late July to mid-August. The Perseids could just as easily have received the tongue-twisting moniker of the ‘Cassiopeiaids’ or the ‘August Camelopardalids.’ The source of the Perseids is comet Comet 109P/Swift-Tuttle discovered by Lewis Swift and Horace Tuttle in 1862. Comet Swift-Tuttle reached perihelion on 1992, and visits the inner solar system once again in 2126.

The Perseids are also sometimes referred as the “Tears of Saint Lawrence” who was martyred on a hot grid iron on August 10th, 258 AD.

The Perseids have been especially active in recent decades, following the perihelion passage of Comet Swift-Tuttle.  Meteor showers come and go. For example, the Andromedids were a shower of epic storm proportions until the late 19th century. We have records of the Perseids back to 36AD, but on some (hopefully) far off date, the debris path of Comet Swift-Tuttle will fail to intersect the Earth’s orbit annually, and the Perseids will become a distant memory. During previous years, the Perseids exhibited a peak of ZHR= 95 (2015), 68 (2014), 110 (2013), 121 (2012) and 58 (2011). Keep in mind, the Perseids have also sometimes displayed a twin peak during previous years, as well.

An early snapshot of the activity for the 2016 Perseids. image credit: The International Meteor Organization.
An early snapshot of the activity for the 2016 Perseids. Image credit: The International Meteor Organization.

Observing the Perseids

The best instrument to observe the Perseids with is a pair of old fashioned, ‘Mk-1 eyeballs.’ Simply lay back, warm drink in hand, and watch. Remember, the quoted ZHR is an ideal rate that we all strive for, though there are strategies to maximize your chances of catching a meteor. Watching early in the morning when the radiant rides highest (around sunrise in the case of the Perseids), seeking out dark skies, and enlisting a friend to watch in an opposite direction can raise your hourly meteor count.

perseid meteor
An early Perseid captured by Chris-Lyons. Image credit and copyright: Chris Lyons.

Keep a pair of binoculars handy to examine any persistent glowing trains and lingering smoke trails from bright fireballs. Monitoring the FM band for the pings of accompanying radio meteors can add another dimension to an observation session. The ionized trail of a meteor can very occasionally reflect the signal of a distant radio station, bringing it through clear for a few seconds before fading out.

Also, keep an ear out for an even stranger phenomenon, as bright meteors are sometimes accompanied by a hissing or crackling sound. Long thought to be a psychological phenomenon, a team of Japanese astronomers managed to catch recordings of this strange effect during the 1988 Perseid meteors.

Imaging meteors is also pretty straight forward. Simply tripod mount a DSLR with a wide field lens, take some test exposures of the sky to get the ISO, f-stop and exposure combination just right, and begin taking exposures 30 seconds to five minutes long. An intervalometer can automate the process, freeing you up to kick back and watch the show.

Got science? Be sure to send those meteor counts into the International Meteor Organization (IMO) and watch their live updated graph as the shower progresses.

Also, be sure to tweet those meteor sightings to #Meteorwatch.

The 2013 Perseid Meteor Shower: An Observer’s Guide

Get set for the meteoritic grand finale of summer.

Northern hemisphere summer that is. As we head into August, our gaze turns towards that “Old Faithful” of meteor showers, the Perseids. Though summer is mostly behind us now, “meteor shower season” is about to get underway in earnest.

Pronounced “Pur-SEE-ids,” this shower falls around the second week of August, just before school goes back in for most folks. This time of year also finds many the residents of the northern hemisphere out camping and away from light-polluted suburban skies.

This year also offers a special treat, as the Moon will be safely out of the sky during key observation times. The Moon reaches New phase on August 6th at 5:51 PM EDT/ 9:51 Universal Time (UT) and will be a 32% illuminated waxing crescent around the anticipated peak for the Perseid meteors on August 12th. And speaking of which, the Perseids are infamous for presenting a double-fisted twin peak in activity. This year, the first climax for the shower is predicted for around 13:00 UT on August 12th, favoring Hawaii and the North American west coast, and the second peak is set to arrive 13 hours later at 02:00 UT, favoring Europe & Africa.

Nodal crossing for the Perseid stream and Earth’s orbit sits right around 18:00 to 21:00 UT on August 12th for 2013. The shower derives its name from the constellation Perseus, and has a radiant located near Gamma Persei at right ascension 3 hours 4 minutes and a declination of +58 degrees. Atmospheric velocities for the Perseids are on the high end as meteor showers go, at 59km/sec.

Of course, like with any meteor shower, it’s worth starting to watch a few days prior to the peak date. Although meteor streams like the Perseids have been modeled and mapped over the years, there are still lots of surprises out there. Plus, starting an early vigil is insurance that you at least catch some action in the event that you’re clouded out on game day! Like we mentioned in last week’s post on the Delta Aquarids, the Perseids are already active, spanning a season from July 17th to August 24th.

The Zenithal Hourly Rate for the Perseids is generally between 60-100 meteors. The ZHR is the number of meteors you could expect to see during optimal conditions under dark skies with the radiant directly overhead. Rates were enhanced back in the 1990’s, and 2004 saw a ZHR of 200.

The orbit of comet Swift-Tuttle and its intersection near the Earth's orbit. (Created the author using NASA/JPL ephmeris generator).
The orbit of comet Swift-Tuttle and its intersection near the Earth’s orbit. (Created by the author using NASA/JPL ephemerides generator).

The source of the Perseids is comet 109P/Swift-Tuttle. Discovered on July 16th-19th, 1862 by astronomers Lewis Swift & Horace Tuttle, Swift-Tuttle is on a 133.3 year orbit and last passed through the inner solar system in late 1992. This comet will once again grace our skies in early 2126 AD.

The Perseids are also sometimes referred to as the “tears of St Lawrence,” after the Catholic saint who was martyred on August 10th, 258 AD. The Perseids have been noted by Chinese astronomers as far back as 36 AD, when it was recorded that “more than 100 meteors flew thither in the morning.” The annual nature of the shower was first described by Belgian astronomer Adolphe Quételet in 1835.

Enhanced rates for the Perseids marked the return of comet Swift-Tuttle in the 1990s. Recent years have seen rates as reported by the International Meteor Organization at a ZHR=175(2009), 91(2010), 58(2011), & a resurgence of a ZHR=122 last year.

Just what will 2013 bring? There’s one truism in meteor observing—you definitely won’t see anything if you do not get out and observe. Meteor shower observing requires no equipment, just clear skies and patience. Watch in the early hours before dawn, when the rates are highest. Meteors can occasionally be seen before midnight, but are marked by lower rates and slow, stately trains across the sky. Some suggest that best viewing is at a 45 degree angle away from the radiant, but we maintain that meteors can appear anywhere in the sky. Pair up with a friend or two and watch in opposite directions to increase your meteor-spotting chances.

We also like to keep a set of binoculars handy to examine those smoke trains left by bright fireballs that may persist seconds after streaking across the sky.

And speaking of which, there has also been some spirited discussion over the past week as to whether or not the Perseids produce more fireballs than any other shower. I certainly remember seeing several memorable fireballs from this shower over the years, although the Geminids, Leonids and Taurids can be just spectacular on active years. The stated r value of the Perseids is one of the lowest at 2.2, suggesting a statistically high percentage of fireballs.

And in the realm of the strange and the curious, here are just a few phenomena to watch/listen for on your Perseid vigil;

–      Can you “hear” meteors? Science says that sounds shouldn’t carry through the tenuous atmosphere above 50 kilometres up, and yet reports of audible meteors as a hiss or crackle persist. Is this an eye-brain illusion? Researchers in 1988 actually studied this phenomenon, which is also sometimes reported during displays of aurora. If there’s anything to it, the culprit may be the localized generation of localized electrophonic noises generated by Extra/Very Low Frequency electromagnetic radiation.

–      Can meteor streaks appear colored? Green is often the top reported hue.

–      Can meteors appear to “corkscrew” during their trajectory, or is this an illusion?

A Perseid very near the shower radiant during the 2012 shower. (Photo by author).
A Perseid very near the shower radiant during the 2012 shower. (Photo by author).

Wide-field photography is definitely a viable option during meteor showers. Just remember to bring extra charged batteries, as long exposure times will drain modern DSLRs in a hurry!

And did you know: you can even “listen” to meteor pings on an FM radio or portable TV? This is a great “rain check” option!

And there’s still real science to be done in the world of meteor shower studies. The International Meteor Organization welcomes counts from volunteers… and be sure to Tweet those Perseid sightings to #Meteorwatch.

Also be sure to check out the UK Meteor Observation Network, which has just launched their live site with streaming images of meteors as they are recorded.

Good luck, clear skies, and let the late 2013 meteor shower season begin!

-And be sure to post those Perseid pics to the Flickr forum on Universe Today… we’ll be doing photo essay roundups from observers around the world!