Stargazers rejoice, the Geminid meteor shower reaches its peak later this week and this year’s celestial display is particularly spectacular.
Have you ever seen a shooting star?
If not, the next few nights will be the perfect introduction, as the peak of the best meteor shower of the year – the Geminids – is expected to occur on the evening of December 14th through the morning of December 15th.
While the Geminids are a reliable annual spectacle, this year is the ideal opportunity to get out and watch them.
For one, when the Geminids reach their peak, the moon will be new, meaning it will be below the horizon all night and the sky will be really dark – perfect conditions for meteor watching.
Even better, this year’s peak of the shower occurs just as the Geminids are highest in the sky at Earth’s eastern longitude, meaning spectators will have a perfect ringside seat for the best of it this year Have a spectacle of natural fireworks.
For the best views, head out in the early hours of Friday, December 15th and spend some time relaxing and gazing at the sky, ideally somewhere with dark skies, away from the bright city lights.
See what the views will be like near where you live and when is the best time to observe in the interactive display below.
Meteors can be seen in any part of the night sky, but when you track the direction of their movement, they always point to this single point in the night sky – the so-called “radiator” of the meteor shower.
Meteor showers are named after the constellation in which this radiator is located. The Geminids radiate from a point in the constellation Gemini.
The good news is that the further north you are, the higher the Geminid radiant will rise in the sky over the course of the night and the better visibility you will have.
From a latitude perspective, about 30 degrees north of the equator – so close to cities like Delhi, Osaka and Tokyo – gives you the perfect view, as the Geminids radiate in the morning hours from a point in the sky directly above you.
Astronomers quantify the strength of a meteor shower by calculating its “zenithal hourly rate.”
This is the theoretical number of meteors you would see in an hour if the meteor shower’s radiation was perfectly overhead, you were in a completely dark place with no light pollution or cloud cover, and you had perfect vision.
The actual number of meteors you will see will always be fewer.
The lower the position of the radiant in the sky, the fewer meteors you will see. When there is strong light pollution, the fainter meteors are not visible to you, so the rate you see also drops.
At their peak, the Geminids have an hourly zenith rate of about 150. So under perfect conditions, when the radiant is directly overhead, you can expect to see two or three meteors per minute.
However, it’s important to note that meteors are like buses – you can wait five minutes and see nothing, and then three come by at once.
See the interactive image above for a more realistic hourly rate of how many meteors you can expect at your location as the Geminids move through the night sky.
However, if you are observing from a location where the sky is light polluted or the sky is partially covered by clouds, expect this rate to be lower.
What makes the Geminid meteor shower so special?
The Geminids are the most active of all the meteor showers Earth experiences during the course of a year.
Every December, our planet plows through the debris left behind by an asteroid called 3200 Phaethon – a potato-shaped lump of rock and metal about 5 km across that is often called a “rock comet.”
Phaethon moves in an extremely elongated orbit around the sun.
The farthest from our star is well outside the orbit of Mars, where Phaethon’s surface temperature likely falls below -100 degrees Celsius.
Because Phaethon is the closest to the Sun, it is much closer than Mercury’s orbit, superheating its surface to temperatures of over 700 degrees Celsius.
These temperature extremes are enough to fracture and shatter the surface rock as it repeatedly expands and contracts.
As a result, Phaethon constantly sheds dust – especially when it is closest to the sun.
Over hundreds of years, this dust has accumulated and spread throughout Phaethon’s orbit to form a giant, dusty tube in space.
Every December, the Earth passes directly through this tube – and we get to enjoy the Geminid meteor shower.
Phaethon’s dust grains hit our planet at enormous speeds – about 34 km per second.
These dust grains carry an incredible amount of energy. As they travel deeper into Earth’s atmosphere, they superheat the air around them and create a spectacular flash of light in the sky, a shooting star. The resulting radiation completely vaporizes the dust grains, a process known as “ablation.”
A typical meteor, as bright as the brightest stars, may be no more than a millimeter or two in diameter.
Earth first enters the debris left by Phaethon around November 19th and does not leave until December 24th.
But most of the time, Earth hovers on the edge of the Phaethon debris, and there are very few Geminid meteors streaking across our sky.
When Earth reaches the center of Phaethon’s debris flow on December 14th and 15th – where the dust is densest – the number of visible meteors will reach a sharp peak.
So the best time to watch the shower is the evening of December 14th to the morning of December 15th, with the nights before and after also offering good sky fireworks.
Tips for watching a meteor shower
When watching meteor showers, comfort is probably more important than anything else.
Plan a trip to a dark place – the darker the better. The further you get from the bright city lights, the darker the sky becomes and the better the display you can see.
Try to get to your viewing point during daylight hours or check it out the day before to find the best place to relax – and remember to check for any hazards beforehand.
Once you arrive at your chosen location, it’s best to lie down to get a good view. Make yourself comfortable because you should spend at least half an hour, preferably longer, looking at the sky.
Take a blanket and pillows, and be sure to bring something warm to wrap yourself up in, even if the night isn’t cold. It’s amazing how cold it can get when you’re lying still outside in the dark.
Find out where in the sky the radiation from the meteor shower will be. For Gemini, look for the constellation Gemini – which is located above and to the left of Orion (for people in the Northern Hemisphere) or below and to the right of Orion (for people in the Southern Hemisphere).
Once you locate the spotlight, look around the sky in that general direction. Do you have darker skies to the left or right of the radiant? Choose the darker side and face that direction.
From many years of experience, I have found that the best way to see a meteor shower is to look about 45 degrees to the left or right of the radiator and tilt your head up so that you are looking about 45 degrees above the horizon.
While you can see meteors from a meteor shower in any part of the sky as long as the radiator is above the horizon, this approach seems to offer the best chance of seeing a really good display.
It takes between 30 and 45 minutes for your eyes to fully adjust to the darkness and for you to be able to see the faintest stars. Any visible light source during this time resets the clock. So be sure to put your phone away.
Now relax, look up at the sky and enjoy the view.
Professor Jonti Horner is an astronomer and astrobiologist at the University of Southern Queensland in Toowoomba. He is particularly interested in the solar system and in particular the comets, asteroids and meteors that occur within it. In recent years, his research focus has expanded to include the search and study of exoplanets.
Originally published under Creative Commons by 360info.
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