Thursday, July 12, 2012

THE PERSEIDS ARE COMING! THE PERSEIDS ARE COMING!!


By: Steve Jones, Guest Mouse and Resident Star Trails Guru!
www.sjlarue.com


Yes it's that time of the year again where the Earth's orbit passes through dust from the comet Swift-Tuttle.  It is the one time of the year when people in the northern hemisphere can with almost all certainty look up in the late night sky and within 30 minutes, see at least one shooting star. 




The Perseid Shower begins in mid July and gradually increases in numbers till around mid August where for two or three days there are literally hundreds of meteors hitting the earth's atmosphere and creating trails of fire hundreds of miles long!...can you tell that I LOVE this time of year. I have the fortune of working on second shift, and on my drive home out on the back roads of rural Ohio, I will get to see...and hopefully shoot...hundreds of them.  Anyways the displays will continue through pretty much the rest of the month of August, steadily decreasing in number.  While the shower will be seen all over the night sky, they will seem to originate near the Perseus constellation. 

This year, event will start around July 17th with maybe one or two an hour, and mostly visible in the more northern regions like Canada. The peak will be Aug 11-13 with possibly numbers closer to 100 an hour...that's around one to two a MINUTE! Then from there it will start to decrease in number but continue to show till around the 24th of August.  Providing the skies are clear, it should be especially pronounced this year, because unlike last year the moon will be a near new waning crescent during the peak days, and the remaining moonlight will not be visible during the peek hours of 10-11pm on Aug 12....AND it's on the weekend!

What does this mean for photographers?  It means we put off sleep for another day and get out there and shoot the stars!!!

It means you need to get your gear in order. Tripod, remote shutter release or intervalometer, your smallest mm lens (under 50mm is best) with your widest apertures, star chart (or app), bug spray, companion to share the beauty with ;-D, blanket or chairs, beverages, and a red glow flashlight to protect night vision are the basics.

You need to learn how to use your lens and your camera to shoot the stars. Use “The 600 Rule”  (shutter speed=600/lens mm) to determine a rough maximum shutter speed for “sharp” stars, and then adjust your ISO and shutter speed to reflect what you want in the final image. Generally anywhere from 25-35sec will be a good starting point, but each lens/body combination will be different.  For example most consumer cameras have a crop factor that will need to be dealt with.  This is the one and only time I ever care about crop factor because it will affect the final picture. An example is an 18mm lens is really a 27mm lens when your body has a 1.5 crop factor, so when you do your rule of 600 calculations, the shutter speed will now be 22sec, instead of 33sec.  Personally, unless you are pixel peeping, an extra 3-5 seconds are not going to make a huge difference in the final image, so just use the Rule of 600 number as a starting point and go from there.

You need to find a dark unobstructed area where you can at least see the big dipper (Ursa Major) and north star (Polaris)...If you are in the city, you need to get out of town and go to a nearby park.  The more stars you can see the better...I can see parts of the Milky Way from my house, but I am still going out to darker areas out of town to shoot.

While the shower will be seen all over the night sky, they will seem to originate near the Perseus constellation. When setting up your camera, if you point the camera at the North Star, meteors will appear as bright lines streaking across the frame. If you point the camera to the NNE, where Perseus is, then the meteors should appear as lines radiating out from the middle of the frame, so plan your shot accordingly...I might do both, but I am first going to shoot to the north since I will not have to move my camera to keep Perseus in frame. 

There are tons of resources out there for locating Perseus, but basically look to the North for the BIG W (or M) of Cassiopeia then look a little lower on the horizon and to the left.  As the night continues on, Cassiopeia and Perseus will continue to rotate through the night sky.

So get out there and get ready; practice shutter speed and ISO settings; schedule days off work if you need to; the Perseids are coming! The Perseids are coming!!

~~~
Thank you Steve for this contribution!
To see more of Steve's work check out his site!
www.sjlarue.com


Find him on Facebook:

PhotoTips Forum on Star Trails: http://forum.myprofoto.com/viewtopic.php?f=78&t=11416&view=next&sid=e35c339787ce72d17275dd1d4c049185
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Resources:


EarthSky's meteor shower guide for 2012 | Astronomy Essentials | EarthSky
http://earthsky.org/astronomy-essentials/earthskys-meteor-shower-guide


Space Weather's prediction center (USA & Canada): http://spaceweather.com/flybys/index.php


Space Weather's prediction center  (International): http://spaceweather.com/flybys/country.php?PHPSESSID=4k8lq5ei7669r4cend34gi8ti1


NASA's Applet: http://spaceflight1.nasa.gov/realdata/sightings/

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