Get ready for the Geminids, the best meteor shower of 2017
Tuesday, December 12, 2017, 2:34 PM - We are in the midst of Fall, and with the weather cooling down and the longer nights, there's plenty to get out and see in the night sky. Here are the best skywatching events still left to see this season.
Geminid Meteor Shower - Dec 13-14
Several times each year, as Earth travels around the Sun, the planet passes through narrow streams of ice, dusty and rock, left behind by the repeated passage of comets through the inner solar system. When this happens, the debris in these streams is swept up by Earth's atmosphere, and the tiny bits of ice and rock cause brief streaks of light in the night sky that we call meteors.
While we can see individual meteors (called sporatics) on pretty much any night of the year, the concentrations of meteors from these streams of debris are called meteor showers.
The radiant of the Geminid meteor shower, after midnight on the night of Dec 13-14. Credit: Stellarium/Scott Sutherland
The August Perseid meteor shower is often held up as the best meteor shower of the year, but the Geminids are definitely a contender, and in 2017, they might be unmatched!
Not only do the Geminids deliver more meteors - around 120 per hour when it peaks on the night of December 13-14 - but this year there are nearly perfect conditions for seeing them. The waning crescent Moon rises very early in the morning, so much of the night will be free of the Moon's light, and even after it rises, it won't offer up much of a challenge to the Geminids.
One of the remarkable things about the Geminid meteor shower is that it originates from a rare object, 3200 Phaethon, which is a so-called rock comet.
So, what's a rock comet? Normal comets throw off a combination of ice, dust and rock as they travel around the Sun, and its thick debris that produces the meteors in our sky. Rock comets leave behind just dust and rock, and the more 'durable' a meteoroid is, the brighter and more long-lasting the meteor it produces will tend to be. That makes the Geminid meteors bright, but due to the minerals and metals contained in the debris from 3200 Phaethon, Geminid meteors tend to be multi-coloured!
With the combination of great dark sky potential, due to the thin crescent Moon only rising in the hours just before dawn, the meteor shower scheduled to reach its peak just after midnight, and the number and brightness of the Geminid meteors, this is one we simply can't miss!
How to watch meteor showers
The first thing to consider when planning to watch a meteor shower is to keep track of the weather. Below is the cloud forecast, across Canada, from Wednesday evening in the east through until early Thursday morning in the west.
Next, you need to get away from city lights, and the farther away you can get, the better.
For most regions of Canada, getting out from under light pollution is simply a matter of driving outside of your city, town or village. Some areas, though, such as southwestern and central Ontario, and along the St Lawrence River, the concentration of light pollution is very high. Getting far enough outside of one city to escape its light pollution, unfortunately, tends to put you under the light pollution of the next city over. In these areas, there are dark sky preserves, however a skywatcher's best bet for dark skies is usually to drive north.
Once you've verified you'll have clear skies, and you've escaped from urban light pollution, stop somewhere safe and dark (provincial parks, even if you're confined to the parking lot, are usually an excellent location). Give your eyes between 30-45 minutes to adapt to the dark. During that time, avoid all bright sources of light, including your cellphone screen. Consider lowering the amount of blue light your screen gives off and reduce the brightness. Also look into an app that puts your phone into "night mode", which shifts the screen colours even more into the red. Once you've done that, checking your phone while skywatching won't impact on your nightvision as much.
Although the graphics presented here point out the location of the meteor shower radiants, which is the point in the sky where the meteors appear to originate from, the meteors themselves can show up anywhere in the sky. So, the best way to watch a meteor shower is to look straight up. That way, your field of view takes in as much of the sky as possible, all at once. Bring a blanket to spread on the ground, or a lawn chair to sit in, or even lean back against your car. Bringing along some family and friends is also great, since it's best to share these experiences with others.
What we've already seen
2017's Perigee Full Moon - Dec 3-4
On the night of Sunday, Dec 3, we saw the largest Full Moon of this year!
The Moon's orbit around Earth is elliptical, rather than circular, so at times it is closer to us, and other times it is farther away. As this happens, month by month, there are certain Full and New Moons that are closer than others. If the Full Moon or the New Moon occurs when the Moon is closer than 361,524 km (90 per cent of the average distance between the Moon and Earth), it's known - at least colloquially - as a Super Moon.
Super Moons can appear up to 14 per cent larger than a "normal" Full Moon, and about 30 per cent brighter.
There can be a few Super Moons during each year. In 2017, there have been 3 so far - the Super New Moons on April 26, May 25 and June 24. They weren't very noticeable, since we were only seeing the dark side of the New Moon when each happened, but the one in December was much more noticeable - the Super Full Moon, on the night of Dec 3-4.
This particular Full Moon was also the closest (and thus largest) Full Moon of the entire year. In astronomical terms, that made it 2017's perigee Full Moon.
The Full Moon on December 3-4, compared to the Full Moon of June 8-9. Credit: NASA GSVS/Scott Sutherland
The image above shows the 2017 perigee Moon, which occurred on the night of December 3-4, compared to the June 8-9 apogee Moon - the farthest (and smallest) Full Moon of the year. (Perigee = the closest point in the Moon's orbit. Apogee = the farthest point in the Moon's orbit). It's difficult to really notice the size difference of the Moon when you're only seeing it, by itself, in the sky, but the difference between the two, shown here, is quite remarkable.
Planets are among the brightest objects in our night sky, with some easily seen even under the worst light pollution conditions. Seeing one planet is noteworthy enough. Catching two or more in the sky is remarkable. Seeing two (or possibly more) that are very close together - a conjunction - is extremely cool.
This season, there are two exceptional planetary conjunctions visible from at least part of Canada, and there's a very nice lineup of planets that will be visible, as well.
This animation shows the position of the planets on the mornings of October 5, October 18, and November 13, 2017. Credit: Stellarium/Scott Sutherland
In the pre-dawn hours of October 5, the planets Mars and Venus appear very close together in the eastern sky - close enough that they may look like they're touching. Through binoculars or a telescope, more distance will likely be visible between them (and of course, out in space, they are actually billions of kilometres apart). The combined light of both planets will be quite a sight, however. The only caveat for this event is that the eastern half of Canada may not see it, because the two planets will probably be lost in the light of dawn. The western half of Canada has a better chance of seeing it.
Early on October 18, before sunrise, look to the East to see Mars and Venus, now quite far apart, line up almost perfectly with the sliver of a crescent Moon.
On November 13, also in the pre-dawn hours, two more planets link up in the night sky, but this time, it's the two brightest planets in the sky - Venus and Jupiter! Just like with Mars and Venus in early October, the two will be so close together as to appear to actually be touching, when viewed with the unaided eye.
Orionid Meteor Shower - Oct 21-22
While there are five meteor showers in Fall of 2017, the Orionid meteor shower is the first one that we'll be able to see well, depending on the weather.
The radiant of the Orionid meteor shower, after midnight on the nights of Oct 21-22. Credit: Stellarium/Scott Sutherland
The Orionid meteor shower is the second meteor shower of the year that originates from Halley's Comet (the first is the eta Aquariids in April/May). The Orionids begin on October 2 and run until November 7, each year, but the best time to watch this meteor shower is during its peak, on the night of October 21-22.
This particular meteor shower is only a moderate one, delivering around 20 meteors per hour under ideal conditions. One great thing about the Orionids, however, is that the meteors can be quite bright!
As one example, here is an Orionid meteor that was spotted by the University of Toronto Scarborough Observatory's all-sky camera on the night of October 18, at around 11:11 p.m. ET (3:11 UTC 19 Oct).
Leonid Meteor Shower - Nov 17-18
The radiant of the Leonid meteor shower, after midnight on the night of Nov 17-18. Credit: Stellarium/Scott Sutherland
From November 6-30, each year, Earth sweeps through a stream of debris left behind by Comet Tempel-Tuttle. As we get deeper into the stream, the number of meteors seen in the sky increases, and reaches a peak on the night of the 17th. As all of these meteors can be traced back to a point of origin in the sky that's inside the constellation Leo, this is called the Leonid meteor shower.
Unlike most other meteoroid streams, which contain only minuscule bits of dust and ice, the stream for the Leonids also contains many gravel-sized bits. When these pebbles hit Earth's atmosphere, they produce very bright meteors in the night sky.
This shower is a fairly minor one, overall, producing around 15 meteors per hour, on average. On occasion, though, usually shortly after Comet Tempel-Tuttle makes a pass around the Sun, the Leonids can deliver a meteor storm - with hundreds of meteors streaking through the sky every hour. According to experts, such a storm is not expected again until 2033 or 2034.
Since the Moon was almost at its "New" phase at the time of the shower peak, the skies were dark enough to provide good viewing, so this was a worthwhile shower to watch.