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Look, Up in the Sky! Perseid Meteors, August 12–13
Every mid-August, the Earth crosses the orbit of Comet 109/P Swift-Tuttle, and as debris from the comet enters the Earth’s atmosphere, meteors will be seen in the night sky with paths pointing back toward the comet’s orbit (the radiant of the meteor shower). As you might expect, for the Perseids this is in the constellation of Perseus which, for observers in temperate latitudes of the northern hemisphere, will be in the northeast sky in the evening hours, rising higher in the sky as the night progresses. Meteors can appear anywhere in the sky, but if you trace their paths back, they’ll converge at the radiant (with the exception of sporadic meteors which occur all the time and are unrelated to the meteor shower). You can produce a custom sky chart for your latitude, longitude, and observing time using Your Sky to help locate Perseus.
This promises to be an excellent year for the Perseids. The number of meteors you can see depends in large part on how dark the sky is when you’re viewing them (as with most things in nature the principle of mediocrity applies and there are many more dim meteors than bright ones: with a dark sky and eyes well adapted to the dark you will see more of these). This year the Moon will be nearly new on August 12–13 and will not interfere at all with observing the Perseids. In addition, calculations suggest that this year the Earth may be passing through a part of the comet’s orbit containing debris shed during its 1862 return (the comet’s orbital period is 133 years), so there may be more Perseids than usual. With dark skies you can usually expect to see around a meteor a minute after midnight local time at the peak of the shower.
This year’s Perseid peak is expected to be around 08:00 UTC on August 13, which is 04:00 EDT and 01:00 PDT on that day in the U.S. The peak is broad, and you will observe around the same number of meteors for hours around the peak. In fact, a substantial number of Perseids can be seen on the days before and after the peak, so since you never know what the weather may do, hedge your bets.
If you want to try to capture a Perseid photographically, it’s pretty easy, but you’ll need a basic camera and a tripod; a mobile phone camera won’t work. Place the camera on the tripod and aim it toward the northeast, elevated so only the sky appears in the field (you don’t want lights on the horizon interfering with the picture). Set the camera for manual aperture and exposure time mode. Use the widest angle lens or zoom lens setting available and the largest aperture available. I normally use a 24 mm f/2 lens on a full-frame DSLR. Set the exposure time to the longest available or, if an option, “Bulb”, where you can manually open and close the shutter. The ISO sensitivity should be set to the highest value which produces images with acceptable noise levels; depending on your camera this may be anywhere from ISO 400 to 3200. Now just take lots of long exposures and hope that one or more of them captures a meteor in the direction the camera’s pointing. Here are some examples of the kind of images you may get: 1, 2, 3, 4, 5.
Photo credit: Perseid meteor photographed after midnight UTC on the morning of August 13, 1993 by John Walker about 15 km northeast of Neuchâtel, Switzerland, on Kodak Ektar 1000 film with an ancient Nikkormat FTn with a Nikon f/1.4 50 mm lens at full aperture in a multi-minute exposure. The meteor is travelling left to right. The image was scanned from a 3×4 cm region of a 10×15 minilab print and contrast stretched to approximate the appearance of the original print. This image is in the public domain.
i was hoping you’d write about this. We neophytes needed some guidance.
so. very. cool.
It is cloudy today in PA, so I’ll check tomorrow.
Thanks for the “heads up”. I’ll be looking for them.
Three cheers for the Perseid meteors! I”ll be in northern Minnesota under dark skies later this week at a star party. I’m hoping to get some great image time with the scopes and camera.
I’ve been curious about this part. Debris shed from the comet could continue in the same orbit, or it could be ejected into a different orbit. What is the calculation that associates specific debris in 2015 with a specific pass of the orbit?
Debris ejected from a comet (the dust tail, primarily) is affected by solar radiation pressure and interaction with the solar wind. Thus material from the comet’s tail during a perihelion pass will be in a slightly different orbit from the comet’s nucleus. The calculations of where clusters of debris from previous perihelion passages will be along the orbit are very wooly; sometimes they’re wrong, but they’re right sufficiently often that people pay attention to them.
John, what do you think of the Dark Sky effort? I was just in Cherry Spring State Park in Pennsylvania, which is heralded as one of the darkest places in the North East US.
A moment’s thinking made me question that claim, as I find it hard to believe it’s darker than northern Maine.
So I suspect there’s a marketing component to it, but it seems to be a worthy idea…
As a resident of PA, I am impressed, and surprised this is set up as well as it is for the stargazing purpose.
I live in PA, and my experience says that the Potter Co. area of PA is quite remote, and would probably be as dark as Maine. It may be that the specific geography of this park, on the mountain, where much of the surrounding land is parks and gamelands, does not experience much night light beyond stars and moon.
It’s not close to me, but I may have to take a visit.
Potter County is ~700k acres. The North Maine Woods is ~3.5 million acres. You see my point…
I once spent 3.5 hours driving across a dirt road to get to a remote spot in the middle of the North Maine Woods.
Nevertheless, I’m eager to visit Cherry Springs…
Oh, and as a neat aside, if you have the opportunity to visit that spot, do so. The proprietor is Igor Sikorsky III. That Sikorsky—he and his wife were lovely. Nearby is one of the few remaining primordial forests in America.
I’ve not been there in 15 years, and am due for a trip back.
My wife was driving us across the Texas panhandle in a comfy rentacar and I needed to get out of the car “for a moment”. She got out in a moment and nearly fell backward once she looked up. She’s been in one of the brightest areas on earth for most of her life, but she loves the night sky. She got more than she expected.
Meanwhile, I’ve seen the sky from a moonless Indian Ocean, and that is unsettlingly awesome. There’s an old science paradox about the night sky not being simply full of light. Well, to nip that in the other bud — it is*. If it’s dark enough, and your eyes adjust, it seems you can make out tiny points of light at literally every location. The exceptions are clouds of dust, which you can often make out as three-dimensional clouds rather than mere dark smudges under the right conditions.
One more reason I’m tired of living in all this brilliance.
*I realize that’s not the point but on the right kind of night, that doesn’t matter.
Thank you! I’ll be gazing for sure.
I think it will be dark enough. I grew up in sullivan county, and there are stars a-plenty in the northern parts of PA.
I see your point in comparing Maine to Potter County…but also remember, the surrounding areas in PA and NY are also just as dark. The forested and unpopulated areas cross the state line.
edit: That place is Maine is very remote. and the lakeside of the camp would be a wonderful star viewing place.
very very cool
If you’re into that sort of thing it turns out Rickett’s Glen State Park also has a primordial forest. We stopped briefly on our way home to see the lowest waterfall, but I didn’t realize about the forest then.
There’s another one on the island of Manhattan, in NYC, of all places.
The International Dark-Sky Association has done tremendous work for decades. Their members have managed to persuade numerous communities that street lighting which sends half the light up into space costs more than well-designed fixtures that don’t. Even if the dark sky argument doesn’t persuade them, cutting the electricity bill in half may.
Here are dark sky maps for various continents. They are based on relatively old data, but light pollution doesn’t change that quickly.
Awesome map. the Maine location mention is smack in the middle of the darkest level. the Cherry Spring is in the middle of the next level.
Thanks for sharing this.
Yes, thanks. I guess the big deal about Cherry Springs is that it’s in the middle of such a highly populated area. No one wants to go to northern Maine…
Yes, as soon as I saw the map, I thought, Kudos to PA for accessorizing that resource, and for promoting it. Something good…
Hopefully our rainstorm will end in time for me to view these tonight. I live in rural NH on the south side of a small mountain, so generally I don’t have much light pollution (except to the east). I have always loved the night sky, but find a camera makes a BIG difference. While it is wonderful what your eyes can see once adjusted, what’s really amazing is what you see off a reasonably high quality CCD (which are common now). With a tripod, a good digital camera with a USB connection to a laptop you can get it all in real-time. Fantastic!
It’s more than a day before the Perseid meteor shower peak, but, having clear skies, I went out to see what might be happening early in the shower.
I wasn’t disappointed. After waiting about ten minutes, around 00:25 UTC, I saw a bright (magnitude ~ −2) meteor with a trail which persisted about one second. If I’d had a camera pointed at it, it would have made a memorable photo, but, alas, I only observed it visually.
The meteor shower only gets better from now until the peak. If you have clear skies, don’t miss it.
I just got back from Ithaca, NY, where I was staying right on Cayuga Lake. I saw a fair number of meteors several days ago.
It’s not always best to point the camera up in the sky. Here’s one from 2009’s shower:
http://www.pbase.com/pderocco/image/116100967/original
Cool. Rain blew through yesterday, cloudless today.
Starry last night, but I did not see anything. Will go out tonight.
I had about half an hour tonight between when the clouds cleared and then rolled back in to observe and photograph Perseids, and here’s what I got.
All of these photos were taken with a Nikon D600 DSLR camera with a vintage Nikon 24 mm f/2.8 manual focus lens. All pictures were taken with the lens set to its maximum aperture of f/2.8, ISO sensitivity of 1600, and an exposure time of 30 seconds. I used an electrical cable release to operate the shutter, which was set to mirror lock-up mode to avoid vibration. I doubt it would have made any difference had I not taken these precautions. The camera was mounted on a tripod aimed in the general direction of the radiant of the meteor shower.
The most spectacular meteor was this fireball, which I estimated at around magnitude −4 (about as bright as Venus ever gets). It left a persistent trail which was visible for about five seconds after the meteor streaked across the sky. This was captured in a corner of the camera’s frame, where the vintage lens, used at full aperture, exhibits obvious coma. Some of the colour in this image may be due to chromatic aberration in the lens. (In normal photographic circumstances you’d never notice these shortcomings; it’s only in the extreme situation of a bright light source against a dark sky with the lens at full aperture that they become apparent.)
Now for some meteors which didn’t blow out the camera and lens.
I didn’t actually see this one myself; I only dug it out analysing the images.
Now, here are two I did see when they happened.
Wow, that is awesome.
I’m planning a little excursion tonight. I can get out of the “red” in the Dark Sky Map in about 15 minutes. Not taking pictures though, just admiring.
The first one might have blown out the camera, but it is a great image.
Just went outside for a few minutes and saw a bunch. Very impressive.
Just got in. I’d managed to not wake hubby. He needs his sleep. Drove myself out to the cornfields west of Toledo. It’s a big world out there alone in the dark. But despite my paranoia about the several cars that passed me . . . and the mosquitoes . . it was good. Even the haze couldn’t obscure the bright trails from the ancient comet debris.
There alone in the night, I reminded myself how lucky I am to have been born in an age when the mysteries of the night sky have been moved from myth and superstition – by science – into the realm of knowledge and understanding.
I only saw a few, but I am satisfied.
I need to drive much further into the dark though.