From The Editors Science

Conditions Ideal for a Spectacular “Perseid Meteor Shower” Experience This Year

109P/Swift-Tuttle is the name of a comet that passes by Earth repeatedly every few years and is predicted to appear again in July of 2126.

With a nucleus measuring 16 miles (24 km), Swift-Tuttle is said to be the largest known object to pass as close to Earth as it does.

As the comet reaches the point in its orbit that takes it closest to the sun, which is called the perihelion, it leaves behind in its wake a trail of debris that collides with the earth’s atmosphere, resulting in a shower of meteors.

Since these meteors radiate from the constellation Perseid, they have come to be known as the Perseid meteors.

As the earth’s orbit comes in contact with that of the comet from July through August, it encounters this river of swirling dust and debris from the comet’s previous pass-bys.

During this period a substantial amount of these 109P fragments comes in contact with our planet’s atmosphere and burn up, leaving in their wake streaks of light that we call meteors.

To get a grasp of the mechanics behind all of this, we need to understand that when a dust particle, which is basically an icy body, slams into the thick blanket of our atmosphere at a mind-boggling speed of about 132,000 miles per hour, or 212,000 km/h, ablation takes place, causing the meteor to burn and disintegrate.

Ablation is nothing but the loss of surface material from a speeding object like a spacecraft or a meteorite through evaporation or melting caused by friction with the atmosphere.

Even small amounts of the comet dust will burn with bright colorful intensity as it disintegrates in the earth’s atmosphere, with about a third of these Perseid meteors leaving behind a luminous plume.

Such conspicuously bright Perseids are what astronomers call “fireballs,” while there are those that have a strobe-like effect, capable of casting shadows, and are known as “boldies.”

Astronomer Bill Cook of NASA’s Meteoroid Environment Office says that more fireballs are produced in a Perseid event than in any other meteor shower we know of.

It will be a relief to know that the likelihood of one of these Perseids actually hitting us is almost zero when you consider that even the deepest penetrating ones can’t make it closer than 45 miles to the earth’s surface, as they get pulverized into nothingness before that can happen.

We can see these meteors streaking through the night sky at ever-shortening intervals, starting July, with the frequency of this spectacular celestial phenomenon peaking sometime in mid-August.

This is the time when the Perseid Meteor Shower is at its most spectacular in the night sky; better than any laser light show you may have seen.

That’s because this is the time when the earth is cutting directly across the orbit of Swift-Tuttle, before which it had been merely skimming the edge of the comet’s flight path since July, as can be seen in the Sky & Telescope Magazine picture below.

The annual Perseid meteor shower occurs when the Earth passes through a stream of dust from the Comet Swift-Tuttle, as shown in this orbit diagram. Credit: Sky & Telescope Magazine
The annual Perseid meteor shower occurs when the Earth passes through a stream of dust from the Comet Swift-Tuttle, as shown in this orbit diagram. Credit: Sky & Telescope Magazine

While the title of the “most prolific” annual meteor event is no longer held by the Perseids, the title having gone to the December Geminids meteor shower, Perseids’ popularity remains undiminished, simply because they happen to occur during pleasant summer nights, as opposed to freezing conditions at the time of Geminids shower.

Although the Perseid show begins at around 9 pm Eastern Time on August 12 this year, the best time to witness the awe-inspiring event is between midnight and pre-dawn – that’s when the show will be at its spectacular best, with the frequency of the streaking Perseids typically reaching 60-80 an hour.

What’s of special significance this year is the fact that the event will be happening at a time when the moon will be a crescent in the sky and will set before the real show begins at midnight, making the conditions ideal for viewing.

The 2018 Perseid Meteor Shower can be best witnessed in the northern hemisphere, although people living as far down as the mid-southern latitudes will also be able to see the heavenly fireworks.

For the best viewing experience, experts advise you to plan ahead by choosing a location that allows you to take in as much of the sky as possible.

Ideally, you should find yourself a vantage point that does not have too much of illumination or obstructions around it; so, the farther you’re away from bright city and town lights, the better your viewing experience is likely to be.

You are also advised to carry a sleeping bag, an air mattress, or even a folding chair if you can because you will need to wait it out for at least half an hour to get your eyes accustomed to the surrounding darkness before you get to enjoy the show.

Make it a point to desist from looking at your bright smartphone display during the wait, if at all you can avoid it, as it will only delay your vision from adapting.

Of course, there is that element of luck that you will also need on your side for a cloudless night, or at least as few clouds as possible during the peak period.

However, if all goes according to plan, you can, practically, guarantee yourself the best Perseid Meteor Shower experience that is sure to stay with you for a long time to come, in the form of memories and pictures you capture of the event.

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