Viewing the Perseids in 2017

Looking north-east from Ireland and UK around 11:30pm on August 12th. (click for large sized graphic)

The ‘Perseid’ meteor shower is probably one of the best known meteor showers of the year.   You probably don’t have to look too far on various social media channels to find ridiculous claims that you will see hundreds or thousands of meteors per hour.  Of course a lot of this is sensationalist nonsense, however the perseid shower is still one of the best showers of the year and is well worth your time and effort.  The purpose of this short article is to debunk some of the myths and prime you to see this lovely shower with reasonable expectation.

So what are ‘Meteors’?

The term meteor refers to small pieces of material from space entering our atmosphere and burning up due to friction.  Usually this results in the complete destruction of the fragment.  Space is littered with tiny fragments of rock and dust.  Almost any clear night you can go outside and if you have enough patience you will see one of these objects being vapourised in our upper atmosphere.  We more commonly call these ‘shooting stars’  The reality is they are not stars at all but usually tiny fleck sized pieces of rock or dust meeting their end in as they collide with our atmosphere at speeds often between 25,000 and 160,000 mph.  At such massive speeds, friction means they are almost instantly destroyed but not before they leave a beautiful streak across the sky.  Often they leave behind a trail of ionised oxygen which can persist for several seconds or even minutes.

What is a meteor shower?

Meteors like the ones descibed above seen on any given night tend not to have a common origin or source.  However at predictable times during the year Earth passes through an area of space rich in such particles.  This is usually material left behind by the earlier passage of a comet.  When this happens we see a large increase of the rates of visible meteors.  We also notice that these meteors appear to ‘radiate’ from a particular point in the sky.  This is a perspective effect similar to the way  train track rails appears to converge on a point in the distance..  Similarly meteors travelling in the same direction are swept up by our planet and appear to radiate from the same point.  At certain times of year Earth passes these locations in our orbit and as we sweep through this dust and debris we see a meteor shower.  A meteor shower is best seen when this occurs at night time (duh!) from our location.  However even they we pass through the thickest part of the stream during the daytime we can still see increased meteor activity in the nights before and after the ‘peak’ of the shower.  Occassionally we get a surprise!  We may be lucky enough to pass through a very dense section of debris.  When that happens the normal shower may turn into a ‘storm’.  Some of the more famously recorded storms such as the famous Leonid Storm in 1966 allowed asome lucky observers to see over 10 meteors per second!

So what are the ‘Perseid’ meteors?

Meteor showers get their names usually from the constellation of stars hich hosts the radiant point.  Some constellations host more than one shower and in this case some showers are named after a star which is close to the radiant such as the Eta-Aquarids which is caused by dust left behind by Halley’s comet.

The ‘Perseid’ meteors appear to eminate from a point in the constellation of ‘Perseus’, hence the name ‘Perseids’.  The material which gives rise to this shower has been left behind by Comet Swift-Tuttle.  Comet Swift Tuttle last passed through the inner solar system in 1992.  Hence the debris stream we pass through is richer and we have a better chance of seeing enchanced activity.

So what about 2017 – Will this be a good year for the ‘Perseids’.

The peak of the Perseids occurs around 6pm on August 12th.  That means the best rates can be seen on the night of 12th/13th.  It’s best to look after midnight as the radiant point will be higher in the sky as the night progresses.  By all means go and look as soon as it gets dark but the later you can watch the better.

Its always good to see Perseids, but this year the peak of the Perseids follows just a few days after the full Moon on August 7th.  The 72% illuminated Moon will wash out many of the fainter meteors but the Perseids often produce bright fireballs which can still be seen despite the bright moonlight.  So 2017 will likely not be a classic year for the Perseids, it’s still well worth seeing some  ancient pieces of space debris meeting their fiery end!  Despite some predictions the likelihood is that the average observer will see a meteor every few minutes certainly not hundreds per hour.  You may see meteors given a figure called the Zenithal Hourly Rate (ZHR) this rate only applies in a very strict set of observing circumstances wihich in reality can never be met therefore I will not even quote such figures when referring to meteor showers.

How should I watch them.  Do I need a telescope?

You definitely don’t need a telescope to see meteors, in fact a telescope is pointless.  Binoculars can be helpful to get a close up of ionised trails left behind but are still far from essential.  A good set of Mark 1 eyeballs are all the optical aid you need.  First remember to wrap up well.  Even on a balmy August night the cold won’t be long about setting in and beleive me its no fun watching meteors when you are shivering.  Grab a comfy chair or lounger and take it as far away from streetlight as possible with a good view to the north-east.  In truth because of the bright moonlight in 2017 there is not much point in travelling too far from the city but definitely find a spot where streetlights are not an issue.

Get comfy and look no the north-east.  Why not print the map above and see it you can identify the constellations listed.  As you do you will see a meteor streak across the sky probably every few minutes.  You might go 5 or 10 minutes and see nothing then you might get a few arriving together.  Meteors can be like that.  In any case be patient and you will be rewarded.  If the sky is cloudy on the night of August 12th/13th consider spending some time either the night before or after.  The rates will dramatically reduch but you should still spot a few meteors and you really can ‘wish upon a star’

Perseids Over Turkey (C) Tunç Tezel (TWAN) 

Here are some reference links for further reading;

International Meteor Organisation