Shooting Stars to Set Your Clock By

The Perseids Meteor Shower only comes around once a year and it is quite a sight to see. Usually. The Perseids Shower will reach its height on August 12th and 13th this year (2022) under rather unappealing circumstances for most viewers, casual or otherwise. The moon will be full.

The moon is the brightest object in the Earth's night sky. When full it obscures nearly everything with its glow. Only the biggest and brightest stars manage to outshine the moon. This means that only the biggest and brightest meteors will be able to outshine it unless you watch for them with a powerful telescope.

A full moon means that viewing the Perseids will be less exciting, but not a complete bust altogether. Viewers will still be able to see an average of 10-20 "shooting stars" per hour according to NASA researchers at the Marshal Space Flight Center in Huntsville, Alabama. While this may not be quite as exciting as the usual 50-150 meteors per hour that the Perseids promise for viewing each year, it will still make for a spectacular show.

So, how exactly do these meteor showers work? What exactly are they made of? How long do they really last? How often do "shooting stars" reach the ground? Do we ever see the actual comet that the meteors come from?

Well, the Perseids are the product of a comet called Swift Tuttle. This particular comet takes roughly 130 years to make one orbit around the sun. That is a long enough period that many people will live and die without ever seeing it! So how do the Perseids happen once per year if we never actually see the comet you might ask? In that 130-year journey that Swift Tuttle embarks on, Earth crosses paths with it, and more accurately the debris field from it, once every year. After all, the Earth orbits the sun every 365 days. The debris then passes through and burns up in Earth's atmosphere, creating what we know as the Perseids Meteor Shower. If one were ever to somehow reach the surface of the Earth, we would have ourselves a Perseids Meteorite!

Try to imagine the tail of the comet, the debris field, as a river the Earth has to wade through each year. The Earth begins its journey in late July, just getting its toes wet on the banks of the river. Then, as mid-August approaches, the Earth wades deeper into the water, moving towards the center of the river, the peak of the Perseids Shower. This is when the most meteors can be seen, up to 150 per hour most years! The true peak nearly always falls between August 11th and August 14th, although meteors can be seen sparingly throughout the entire traversal of the Perseids. As the end of August approaches, the Earth reaches the end of its treacherous journey through the river and emerges on the other bank as the meteors slow, coming to a complete halt by the beginning of September.

We haven't actually seen the Swift Tuttle since it last rounded the sun in 1992, and we won't see it again until it comes back around in 2125. The Earth simply passes through the comet's trail of debris as their orbital paths cross each year. But don't worry, scientists don't think Swift Tuttle will ever hit Earth, though they do predict several close calls in the distant future. Scientists predict that Swift Tuttle will come within one million miles of Earth, a near miss by space standards, in the years 3044 and again in 4479. If any one of us is still alive by the time Swift Tuttle comes by for a close up, a comet ought to be the least of Earth's worries!

So, what exactly is a meteor? The simple answer, it is a shooting star. The long answer, a meteor is a piece of debris from space, usually from a comet or asteroid, that has entered Earth's atmosphere and is illuminated due to high amounts of friction as it tries to push its way toward the surface of the Earth. It is a meteoroid that is streaking across the Earth's atmosphere and usually burns up before ever reaching the surface, creating the brilliant streak of light we call a shooting, or falling, star. Meteors are shooting stars and shooting stars are meteors.

The Perseids Meteors are no different from other meteors, they are debris flung down into the Earth's atmosphere and burnt up, creating a brilliant light show. The meteors that fall during the Perseids Shower are a little different from others in some ways though. They are made up of dust and ice, making them much more fragile than most meteors that are made up of heavy metals. Their fragility is due to their parent being a comet instead of an asteroid. Comets produce meteoroids that consist of mostly dust and ice, while asteroids produce more dense meteoroids due to their composition of heavy metals and other carbide materials.

It is estimated that several thousand meteorites make contact with the Earth's surface each year, though most go unnoticed due to their remote landing sights. Most land in vast expanses of forest or find their way into the depths of the ocean. Even with this seemingly massive number of touchdowns, about 95 percent of meteors burn up in the atmosphere. The Perseids are no exception. They will actually produce no meteorites due to their fragility. Dust and ice are simply no match for the Earth's atmosphere.

So now you know. The Perseids are one of the most viewed, and most visible, meteor showers of the year. The moon may make them a little hard to see this year, but they are still there, like clockwork in the sky. They are also one of the most predictable. The Perseids tie with the Geminid Meteor Shower for first on predictability. The Geminid Meteor Shower peaks like clockwork in mid-December each year. Each shower is so predictable you could nearly set a calendar, or your clock, by them. Which shower do you prefer? Or will you watch both diligently?