Look up! Geminid meteor shower lights up the sky this week
We are fast approaching the peak of the Geminid meteor shower, but the days leading up to it might be the best time to watch this spectacular celestial event.
Look up on any clear night this week and you may spot the occasional streak of light flashing by overhead, as part of the annual Geminid meteor shower. Even better, each night, right up until Friday, December 13, the number of meteors we can potentially see from this event is expected to nearly double.
This will all culminate on Friday night and early Saturday morning, during the meteor shower's peak, when the Geminids can deliver up to 100 meteors per hour.
The radiant of the Geminid meteor shower, in the southeastern sky, on the night of December 13-14, 2024. The nearly Full Moon, Jupiter, and Mars, will all be visible in the sky during the meteor shower's peak. (Stellarium/Scott Sutherland)
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However, although this is one of the three best annual meteor showers — along with the January Quadrantids and the August Perseids — this year, the timing of the Geminids peak does not match up very favourably with the phases of the Moon.
To get the most out of the peak of a meteor shower, there are two ideal conditions. First, having a sky free from cloud cover, so that you can see as much of the sky above as possible. Second, having a completely dark sky, without any sources of competing illumination, such as city lights or the Moon.
This composite image shows several Geminid meteors captured throughout the night during the peak of the shower in December 2012. (Jeff Dai/NASA)
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Even for those who get as far away from urban light pollution as possible, on Friday night, we will have a Waxing Gibbous Moon in the sky, just two days shy of Sunday night's Full Moon. With the amount of light the Moon will be casting that night, it will 'wash out' the sky to some degree, making it more difficult for us to see dimmer meteors. This is similar to the impact of urban light pollution, as the Moon's light prevents our eyes from fully adjusting to the dark.
One way to compensate for the Moon, though, is to turn your back to it. Geminid meteors may stream out of the southern sky, but they can appear anywhere overhead. So, if you face north and then look up, you will keep the Moon out of your direct field of view and improve your chances of spotting them.
However, another way to get more out of the Geminids this year may be to go out to see them before the peak.
We just had the First Quarter Moon on December 8, and we will see more of the Moon illuminated (and thus it will shed more light down on us) as this week progresses.
As the number of meteors ramps up each night, though, there could be a 'sweet spot' in the few days ahead. Perhaps on Wednesday night or even Thursday night, the increasing light reflected from the Moon's surface and the increasing number of meteors flashing through the sky could reach a balance, where we may actually see more of them than will be apparent on Friday night.
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Will there be clear skies?
Since having at least reasonably clear skies is an essential part of watching a meteor shower, here are the forecasted cloud conditions across Canada for the next three nights.
The best regions for viewing the Geminids on Wednesday night are in southern British Columbia, southwestern Alberta, across northern and eastern Saskatchewan, southern Manitoba and western Ontario, as well as parts of southwestern, central, and eastern Ontario.
For Thursday night, British Columbia clouds over, the rest of southern Alberta clears out, with some mixed cloud across southern Saskatchewan, and clear skies for southern and western Manitoba. Some mixed cloud remains across southern Ontario, but there are clearer skies for southern Quebec, New Brunswick, PEI, parts of central and northern Nova Scotia, and western Newfoundland.
On Friday night, when the peak of the shower occurs, skies appear to mostly clear out for Alberta, southern Saskatchewan, most of Ontario, southern Quebec, and the Maritimes (except southern Nova Scotia and the western half of Newfoundland Island).
Check back for updates on the weather over the next two days!
What's going on here?
Meteors are produced by small bits of rock, dust, or ice that are swept up by Earth's atmosphere from space.
These tiny meteoroids are typically travelling at speeds of tens of thousands of kilometres per hour when the hit the top of the atmosphere. At that velocity, they compress the air molecules in their path so tightly that it causes those molecules to glow. This produces the flash of light that we see in the night sky, known as a meteor. Slightly larger meteoroids, from the size of a grain of sand up to a softball, result in a much brighter, longer lasting meteor known as a fireball. An even larger object, up to a metre or more in size, will often produce a bolide — a fireball that explodes high up in the air, briefly lighting up the entire sky as if it was daytime.
The pressure of the air pushing back on them and the heat produced during the meteor flash typically vapourizes smaller meteoroids. However, larger, slower meteoroids can survive their passage through the air, falling to the ground as meteorites.
On any particular night of the year, it's possible to see a few random meteors streak by overhead. Scientists refer to these as sporadics. These are simply bits of solar system debris that are part of the several metric tons of space dust that NASA estimates is swept up by Earth every day.
There are times of the year, though, when we see concentrated bursts of meteor activity. This results from our planet passing through streams of debris, typically left behind by comets, as we orbit the Sun. The meteors from each of these events appear to originate from a different spot in the sky, and we call them meteor showers.
There are a dozen meteor showers every year that are active and consistent enough for the public to enjoy — two in spring, two in summer, six in the fall, and another two in winter.
Each follows roughly the same pattern, starting off with just a few meteors per night as Earth first slips into their stream of debris, then ramping up over days or weeks until their numbers peak when we reach the most concentrated part of the stream, and then they taper off until Earth exits the stream. However, they all begin, peak, and end at different times, and they vary in strength.
Weak meteor showers, like the Draconids or the Ursids, can produce up to 10 meteors per hour during their peak. Moderate ones, like the eta Aquariids or the Orionids max out at anywhere from 20 to 50 meteors every hour. Strong ones, like the Quadrandits, the Perseids, and the Geminids can deliver up to or even over 100 per hour at their peak.
Each meteor shower is also named for the constellation closest to its radiant — the point in the sky where the meteors appear to originate from. In this case, the meteors we are seeing this week appear to streak out of the constellation Gemini. Thus, this is called the Geminid meteor shower.
The orbit of 'rock comet' 3200 Phaethon as it travels around the Sun. The stream of debris that produces the Geminid meteor shower follows this same path. (NASA/JPL-Caltech)
The concentrated stream of dust that causes the Geminids each year appears to come from a giant object in space known as 3200 Phaethon.
While 3200 Phaethon travels like a comet, coming very close to the Sun, and it behaves like a comet, leaving behind debris in its wake, this object is actually a rocky asteroid. Due to this, NASA scientists nicknamed Phaethon a "rock comet".
