2018: A Great Year for Meteor Showers
March 7, 2018
Meteor showers are nature’s fireworks displays. To truly appreciate an active meteor shower, however, you must view it under dark skies. That means getting far away from city lights. It also means considering the phase of the moon. Meteor showers occur on the same dates every year. If the shower happens to coincide with a bright moon (say, 50 percent or more illuminated), the show will be much less impressive. Fortunately, in 2018, both of the year’s best meteor showers, the Perseids and the Geminids, coincide with new moon, creating ideal viewing conditions. The Perseids peak on the nights of August 11-12, 12-13, and 13-14. If you can only shoot one night, try August 12-13. Under ideal conditions, you might see 50 meteors per hour. The Geminids peak on the night of December 12-13. Under ideal conditions, you might see 75 meteors per hour. You’re likely to see the greatest number of meteors in the hours between midnight and astronomical dawn. Now is the time to start planning your 2018 Perseid and Geminid shoots.
Meteors appear in all parts of the sky during an active shower, but if you trace the streaks of light backwards, they all originate at a point called the radiant. Radiants are named for the constellations in which they appear. You can capture meteors by pointing your camera at any part of the sky, but the most interesting photographs of meteor showers are composite images that show many meteors streaking away from the radiant, as you can see in my photograph of the Geminid meteor shower over Turret Arch. Creating such an image requires figuring out where the radiant will be.
Like all celestial objects, radiants appear to move through the sky as the Earth rotates. I’ll use Boulder, Colorado, as the location for the data that follow. You can use Starry Night, from Simulation Curriculum, to get data for your location.
At the latitude of Boulder, the radiant for the Perseid meteor shower is circumpolar—it makes endless circles around Polaris, the North Star, and never sets. On August 12, at 9:44 p.m., astronomical dusk, the radiant has an azimuth (compass bearing) of 30 degrees and altitude (angle above a level horizon) of 20 degrees. By midnight, when the action starts heating up, the azimuth is 41 degrees and altitude is 36 degrees. At 4:28 a.m., astronomical dawn, the azimuth is 25 degrees and the altitude is 69 degrees. In short, the radiant is in the northeastern sky the entire night. If you want to include the radiant in your frame, find a location where you are looking northeast at an interesting geographic feature.
The path of the radiant for the Geminid meteor shower is very different. At 6:13 p.m., astronomical dusk, the radiant has an azimuth of 49 degree and altitude of 4 degrees. The radiant is due east with an altitude of about 58 degrees at 11:21 p.m., transits (reaches its highest altitude, 82 degrees) when it is due south at about 1:58 a.m., and is setting to the west with an azimuth of 279 degrees and an altitude of about 46 degrees at 5:37 a.m., astronomical dawn. No lens except an 8mm fisheye with a 180-degree angle of view can encompass such a wide swath of sky. If you want to include the radiant in the frame, choose a location where you are looking either east or west. If you choose a location looking south, the radiant will be so high in the sky that it will be difficult to include it and a significant amount of land without the radiant being crowded against the top of the frame. (You could, of course, compose the shot with the radiant outside the frame, but I think the graphic impact of the image would diminish.) If you choose a location looking north, the radiant will never be in your frame.
If the thought of pulling an all-nighter to shoot a meteor shower seems daunting, remember your childhood, when staying up all night felt like an adventure. Fill a thermos with coffee, and go. It will be well worth the effort to see one of nature’s most awe-inspiring sights.
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