It’s that time of the year again: the Geminid meteor shower. It is visible almost all the month of December, however the best and peak viewing, with up to 120 meteors an hour, is between December 12 and 15. It should be a good year because we are heading towards a new Moon on December 18th, so no bright moon to ruin the show.
This meteor shower is called the Geminid because the radiant (apparent direction of travel in the sky) of the meteors is centered on the constellation Gemini. However the source of the debris is not a comet like most other meteor showers, but an asteroid: 3200 Phaethon. The asteroid and orbit were discovered in 1983 and is too good of a match with the Geminids to be anything other than the source of the debris. However its makeup is closer to asteroid belt material, so it may very well be a 5km chunk from a larger asteroid, with all the associated debris.
To watch the Geminids, the best time is past midnight as the constellation will rise east around 10pm. The higher it is in the sky the better. The Geminids do regularly create fireballs: bright displays that can exhibit colour and even leave a smokey trail, so observation even in light polluted city sky is possible.
Here are some tips for the observation:
- Dress to be warm. You’ll be sitting still in the cold night. Nothing will get you indoors faster than the shivering knowing that warmth is only a few feet away.
- Lay down or recline in a chair. Standing and looking straight up is very uncomfortable and quite the strain on the neck.
- Give yourself a good 15 minutes for your eyes to adjust to the darkness If you give up after 2-3 minutes, your eyes are still adapting to night vision and will miss the fainter meteors.
- Find a spot away from sources of lights. Of course heading out of the city is best, but if you can’t, just find a spot in your backyard without the glare of street lights and neighbors’ porch lights. That also means no electronic screens to ruin your night vision.
You can also setup a camera on a tripod to see if you capture some of the meteors. Grab a short focal length, remove auto-focus and go for a 10-20 second exposure setting.
Today I got an e-mail from Gary that a photo of the Big Dipper that I had submitted a few months ago got selected for this week’s column on SkyNews. Couldn’t be happier. I wish all my weeks could start this way.
Astrophotography is a combination of equipment, experience, location/timing and luck. With this photo I just happen to hit everything right and was lucky.
Using the best equipment helps, but for this photo it was the simplest of setup: my very worn Canon Rebel XTi DSLR with a zoom lens set to 17mm F4 mounted on an old steel camera tripod my father used in the 60s. So nothing special, and within everyone’s reach.
OK, for the next part I had experience on my side. It allowed me to pick the right camera settings, but was also lucky as my photo viewing was limited to that small LCD screen on the camera. I had no laptop to fully explore and review the photos and make the necessary adjustments. Even the focus was reviewed through the small camera LCD. That night I only took 4 images with 20 second exposure crossing my fingers that I would have something worthwhile once back home.
And then there is the post-processing on the computer, which is a lot of trial-error. In image processing doing steps A + B will not give you the same results as performing B + A. We all have our “recipes” for what produces good results, but every photo ends up being a unique project. With this one, I knew there was good potential.
Finally there is the location and timing. I was up in cottage country, away from city lights, and a clear sky. However there was a full moon rising, couldn’t wait too long as the sky would start to brighten. A Big Dipper low in the sky next to the trees framed everything very well.
Thanks Gary and SkyNews for selecting my photo. For all the experimentation that I do with the camera, once in a while I get everything right. I’m just happy someone noticed and said “Hey, that’s a great photo we could use.”
Some constellations are easier to spot than others. Cassiopeia with its distinctive W is visible year round in the northern hemisphere above the 34th parallel. In the image below it easily stands out from the fainter background stars.
Cassiopeia above the three line – Benoit Guertin
The five stars drawing a W in the sky are all naked eye magnitude 3 and brighter stars, and in the image above I used a layering technique to increase the color and brightness of those stars to really make them stand out.
- Duplicate your base image, and set this layer to lighten only
- Apply a blur to the top layer(about 8-12 pixels)
- Increase the color saturation and brightness. Play with the curves to brighten the bright stars, but not the background sky.
- Use a mask as required to filter out the bright foreground elements, such as light reflecting off a building roof-line in my image above.
Canon Rebel XTi
4 x 20sec ISO800
If you are able to get out of bed early before sunrise and the sky is clear, you can catch a view of our three closest planets, and if you include Earth that makes 4. Mercury was at the greatest elongation on September 12th (furthest from the Sun when viewed from Earth) which makes it a good time to spot without the glare of the Sun. But it happens that Mars and Venus are also on that same side of the Sun, making a chanced planetary alignment.
The sky map below [click for larger] shows the position of Mercury, Mars and Venus for the morning of the 16 to the 19 of September. Bright star Regulus and our Moon are also there to make this a worth-while event, especially on Monday the 18th.
Mars and Mercury will be closest on the 16th, while the 18th will probably be the most photogenic as the Moon will be a thin crescent in the middle of this alignment.
Ursa Major, or Big Dipper is one of the most recognizable constellation in the Northern hemisphere. People often use it to locate Polaris, the North Star. Can you find Polaris? (Hint: upper right)
Ursa Major (Big Dipper) low in the sky in late summer around 11pm
Canon Rebel XTi (450D)
Stacking of 4 x 20 seconds @ ISO800
Post processing with GIMP
When I took the four shots to create this image below the Moon was just starting to rise above the tree-line behind me. A full moon may be 1,000,000 times dimmer than the Sun it’s still bright enough to cast shadows and considerably light up the scene in a long exposure photo.
Over the mountain top a loose grouping of stars identified as Melotte 111 open star cluster. These are about 40 bright stars laying 280 light years away all moving together. It lies in the Coma Berenices constellation.
Canon Rebel XTi (450D)
20sec @ ISO800
The sky is a stack of 5 x 20sec. The foreground is a single 20sec shot.
Yesterday, even if I’m located in the light polluted Montreal suburb, I decided to head out at quarter to midnight to see if I could by chance spot one or two bright meteors from the Perseids shower. As luck would have it in the 15 minutes doesn’t looking around Cassiopeia I spotted two before clouds and a rising moon sent me indoors.
But during that time scanning and waiting, it got me thinking… It took me a good minute to find a suitable spot in my backyard free of the light from the neighbours’ houses and street lights. If there was less light pollution we could have darker skies and everyone could enjoy the show.
During Earth Hour people are asked to turn off the lights for one hour to support the fight for climate change. But I always found that pretty pointless. If you want to fight climate change, it’s an every day affaire, in your daily routine and the choices you have as a consumer, not one hour in an entire year. So the one hour lights out is more of a gimmick, doesn’t really benefit anyone. But if we had an evening of lights out during the peak of the Perseids meteor shower wouldn’t that be great!
The Perseids falls in August when it’s warm and sitting outside past sunset in the cooling air is enjoyable. Kids don’t have school so they can stay up late. And the patio furniture is out, that’s all the required equipment.
So what do you say? Light out for the 2018 Perseids? I think that’s a worthwhile collective movement.