Geminid meteor shower
The Geminid meteor shower occurs every December and is considered to be one of the best showers as it produces up to 120 meteors per hour at its peak on December 13th. Perhaps known more commonly as shooting stars the Geminid meteor shower can be seen without the use of telescopes or binocular. On the nights leading up to the peak and for a couple of nights after it will be possible to watch this spectacular free show, if you are lucky enough to have clear skies!
What is a meteor shower
As a comet orbits the Sun or moves close to it, it heats up and parts of the comet vaporise. After a comet has orbited the Sun a few times, small pieces of the debris from that comet are left on that path.
A meteor shower occurs when the Earth passes through that path of the comet. Then the bits of comet debris, about the size of a grain of sand, create streaks of light in the night sky as they burn up in Earth’s atmosphere. These bits of debris which enter Earth’s atmosphere are called meteors.
Most nights you can see up to 10 + meteors, and those that are not assigned to a particular meteor shower, are called “Sporadic” meteors. However, during a meteor shower, lots of meteors (100+) can sometimes be seen. These meteor showers have been calculated, observed and allocated a comet or cause, and they occur at the same time each year, we call these “periodic” meteor showers.
There are several minor and major showers throughout the calendar year and December 13th sees the peak of the Geminid meteor shower.
The “Radiant” of a Meteorite Shower
All of the meteors in a meteor shower seem to come from the same direction in the night sky. For us, watching on the Earth, they seem to be coming from “radiate from” a single location in the sky, and this is what we call their “radiant”. It is like driving in a car, at speed, in a snow storm, some snowflakes pass you on your left, some on your right, some over your head even under the car. The direction you are traveling would be the “radiant” point. Meteor showers are named for the constellation from which they appear to radiate as seen from earth as earth speeds through space on its orbit of the sun. So, the “Geminids” appear to be coming from, “Radiate” a point in the constellation of Gemini.
Geminid meteors are very bright and also very fast some up to 80,000 mph, and the shower is famous for producing some spectacular fireballs, which are small particles entering the earth’s atmosphere at that great speed and the friction creating heat which causes these meteors to sometimes be brighter than magnitude -4, that is the same brightness as the planet Venus. Unfortunately meteor showers are very unpredictable: Some meteor showers will put on a great show one year and a mediocre even poor show the following year.
In astronomy we often talk about the “seeing”, this refers to the quality of the sky, the amount of light and other pollution, cloud, moisture and the darkness of the background sky. Here at the Astrofarm we have very good seeing, as there is very little light or other pollution the air, in winter, is very clear, and the background sky is a dark grey almost black colour.
Viewing the Geminid meteor shower
For the best view of these natural spectacles it is best to remember the following list of things you need to do before you go out, things to need to organise, things you need to know and have with you.
1. Plan to observe with others if you can. It always makes more fun in a group. Organise a party, invite friends and neighbours round.
2. Check your sky. Make sure you have a clear view of some or most of the sky. Check the light pollution from the site you want to use. It may be better to find a site outside of towns and cities away from street lighting and orange sky glow.
3. Check the Moon. The full moon is very bright and will block out all but the very bright shooting stars.
4. Check the weather forecast. There is no point travelling a long distance if the weather is going to be bad and you can save yourself and others disappointment.
Plans to observe the Geminid meteor shower
The best made plans also need to be flexible so you may have to change location at the last minute but if you have everything else in place that is all you will have to change. My recommendations for things to take are :
1. Red torch. This will help you to see at night without ruining your or other people’s night vision. As we get older it takes our eyes longer to get “dark adapted”, my eyes need up to 30 minutes to adapt to the night.
2. Warm clothing. The warmer you are the more you will enjoy yourself. This includes hat, gloves even thermals if it is going to be very cold. If you are cold your body will be concentrating on the cold bits and will be telling your brain that you are not enjoying this and that you need to get warm. You will find it harder to concentrate on what you are doing.
3. Warm drinks/food. Soup is great, if not coffee then chocolate or tea with sugar, this also helps to keep you warm.
4. Chair/blanket. If you can take a deckchair or reclining garden chair, that’s much better for reclining back to save your neck. I sometimes use a waterproof backed pick-nick blanket to lay on with a blanket or duvet or sleeping bag.
5. Sky map or chart. This may help locate the constellation.
6. Compass. Helpful.
7. Map of area if you are not familiar with the area.
8. Mobile phone.
9. Some form of counting and keeping record. Not a requirement but can be useful information to a variety of institutes on the internet and you can contribute to science.
For more information about taking part in a meteor count see: http://www.imo.net/
If you are going to a dark, isolated, rural location please tell someone where you are going and when you expect to be back. Remember, while you are out, if you cannot contact someone to let them know, Do not change your plans. Keep safety your priority not the meteors.
Photographing the Geminid meteor shower
As mentioned above, most meteors are very fast and mostly faint; only the odd few are big, bright and slow moving so it is very difficult to image meteors from large towns and cities where there is a considerable amount of light pollution, hard but not impossible. One of the important things to remember is that you need to know your camera and its settings so that you can adjust according to requirements and seeing.
You will need to know how to change the ISO, adjust the shutter speed and open of close the aperture. I also recommend that you make sure that you have all of the items in the meteor observing list above and also the following:
1. Cable release or remote shutter release. Better still is an interferometer. This will allow you to programme your camera to take pictures and allows you to set the time/rate/speed and intervals. These are also good for setting to take loads of images allowing you to sit back and watch and not have to worry about taking pictures.
2. A wide angle lens with low f ratio. A wider angle lens gives you coverage of more sky in one hit. Low f ratio allows more light to hit the camera chip which in turn enables you to get the fainter meteors.
3. Spare batteries. There is nothing worse than running out of battery when you are a long way from home. Batteries run out quicker when they are cold. Check your batteries before you go, make sure you have spare.
4. Tripod. This does not have to be an expensive one, a cheap tripod will do the trick if it’s not too windy, even a bean bag or camera bag to sit the camera on will do.
5. Red light. As mentioned above, it helps when you are trying to set your camera up.
Once you have got all your gear to your location, take some time to set up your site. Orient yourself as to the direction you want to be looking. Use your compass if it is not dark when you get there. Test your camera and set your remote timer ready for nightfall.
There are many ways to take photographs of meteors and this is just “My Method”. If you follow these steps you will soon be taking pictures of the night sky and meteors. You can and will, with experience, adjust your method until you find a way which works best for you and your camera.
I always start by taking a test shot, in “M” manual, of something on the horizon or a bright star if there is one, with the lens focus on “m” manual. It is sometimes difficult for a camera to focus at night when it can’t see the object you are trying to focus on so if you leave your focus on Auto the camera will be constantly trying to focus on something.
With my camera in “M”, lens focus in “m” and shutter speed set to 30 seconds, using live view, I focus on a star or as mentioned an object on the horizon. I do this because I have found that lens infinity are not actually infinity and can be slightly out of focus.
Have fun with the Geminid meteor shower and please do let me know how you got on and if you have any questions before the peak on Sunday please post below and I will answer all your queries.