What’s Up? Meteor Showers
By Adam England
One of the most widely anticipated meteor showers of the year is always the Perseids, culminating this week with their peak on 13 August.
However, with the next full moon just days away on the 15th, many of the normally visible trails of burning rock will be washed out. Even so, the astute observer could still see 10-20 bright outbursts per hour. The rate will increase from about 10PM on to dawn by looking eastward between the constellations Cassiopeia and Orion, best viewed around 3AM.
But what is a meteor, or shooting star?
Ancient cultures attempted to describe these celestial events, but the irregularity of meteor showers proved to be more difficult to predict than the orbits of the planets and seasonal migrations of the stars. Plutarch likened this unpredictability to that of experiencing pleasures, writing, “…Like gales of soft wind, move simpering, one towards one extreme of the body and another towards another, and then go off in a vapor. Nor are they of any long durance, but, as so many glancing meteors, they are no sooner kindled in the body than they are quenched by it.”
The Maya predicted meteor showers and timed significant cultural events to coincide with their arrival. By 900AD, Asian cultures were accurately predicting the annual return of the Perseids.
The first modern study of meteor showers was after the Leonids event in November 1833. Estimates give 200,000 meteors over the 9 hours of the storm that blanketed Western North America. Speculation as to why this was only visible in a specific location and the point in Leo from where they appeared to emanate created a new science of attempting to estimate when and where we would experience showers.
We now know that comets and asteroids leave clouds of debris in their wake, and the orbit of Earth takes us annually back through these trails. It is when we pass through these streams that we experience small grains of dust burning as they enter the atmosphere, and provide us was a natural display unlike any other.
The Perseids is one of these comet trails, left in the cosmic wake of Comet Swift-Tuttle which last passed through the inner Solar System in 1992. Swinging out as far as the orbit of Pluto, it’s orbit is 130.48 years, with the next close approach to the Sun in July 2126.
If you would like to learn more about the sky, telescopes, or socialize with other amateur astronomers, visit our website at www.prescottastronomyclub.org or Facebook page @PrescottAstronomyClub to find the next star party, Star Talk, or event.
Adam England is a local insurance broker and small business consultant who moonlights as an amateur astronomer, writer, and interplanetary conquest advisor. Follow his rants and exploits on Twitter @AZSalesman or at Facebook.com/AdamEfromAZ