December Dark Sky Events

Saturn and Jupiter in the evening sky over Pagosa Springs, Dec 5, 2020 © Andy Butler

As we move towards the shortest day of the year, it’s a good time to think of night photography. There are a couple of significant events coming up that could be of interest to both photographers and stargazers. 

First, the Geminid meteor shower, one of the most reliable meteor showers of the year, will reach it’s peak on the night of Dec. 13-14. With the new moon on Dec 14, skies should be dark enough to see quite a few meteors. However, you should be able to see meteors any night beginning this weekend (Dec. 4).The Geminids appear to radiate from the constellation Gemini, which conveniently is above the horizon before midnight in December. The maximum activity should be after midnight in the early morning of December 14, with up to 75 meteors per hour visible. The Geminids are one of only a couple of major showers derived from an asteroid, 3200 Phaeton, rather than a comet. Look to the east for this shower. 

For best viewing of the Geminids or other meteor showers, find a relatively dark site. If you want to photograph a meteor shower, there are a few things to keep in mind. First, the number of meteors “visible” includes the entire sky, while even a very wide-angle lens is not likely to cover more than 1/3 of the night sky. So you are unlikely to capture more than one shooting star even in a minute-long exposure. Second, if you want to keep the stars as points of light, rather than streaks, you will need to limit your exposure time. A rule of thumb is to limit exposure times to 500 divided by your lens focal length (in full-frame equivalent). So, if you have a 16 mm lens (full frame) then 500/16 is roughly 30 seconds. If you think you will be making large prints from your photos, you should be more conservative, maybe using 20 seconds in this example. A good starting point is to set your aperture to f/2.8, shutter speed 30 seconds, and ISO 6400; basically the same as you would use for Milky Way photos. To increase your chances of getting one or more photos that contain a shooting star, set up your camera to automatically take these 30 second exposures for several hours during the night. To do this, either use your camera’s built in intervalometer, or an external cable release with intervalometer. If you have chosen an interesting foreground subject in the landscape (you should!), it would be good to either take a longer exposure of it, or to take a separate photo of the landscape using light-painting or low level lighting. Back home, check all the photos to find the ones with meteors streaking through the sky. For a dramatic image, you can composite these with your landscape image using Photoshop or another editor. For a very thorough discussion of photographing and processing meteor showers, see: https://www.photopills.com/articles/meteor-shower-photography-guide 

Another event coming up will be a Great Conjunction of Jupiter and Saturn on Dec. 21. Jupiter and Saturn have been appearing closer and closer to one another this fall. Shortly after sunset, around 5:24 PM on the Dec. 21, these gas giants will be visible about 17° above the horizon in the Southwest. They will be within 0.1° of each other, or about 1/5 the apparent diameter of the moon. This is considered to be a “Great Conjunction”, as it happens only about once every 20 years. And in 2020 these planets will appear closer together than they have for about 800 years. The best viewing will be just at the end of civil twilight, so lighting should be good. You can observe these planets near one another on any clear night in December, as they appear closer and closer.  In fact, a few days before the conjunction, on December 16 or 17, you should also be able to see the new Moon very close to the two planets. For information, and some inspirational photos, see https://earthsky.org/todays-image/jupiter-saturn-photos-drawing-closer-conjunction-dec21-2020 .

Author: fotohiker

webs are for spiders

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