Meteors, fireballs and satellites will share an unusually dark sky tonight. Knowing what to look for — and what to record — can help distinguish the identifiable from the genuinely unexplained.
The sky is offering a second spectacle following Wednesday’s solar eclipse: The annual Perseid meteor shower reaches its peak overnight Wednesday into Thursday morning, Aug. 13, under unusually favorable viewing conditions.
The American Meteor Society says the Perseids peak Aug. 12-13, with the Moon at 0% illumination. The organization says observers at rural locations typically see roughly 30 to 50 Perseids per hour around maximum, although actual numbers depend heavily on darkness, weather and observing conditions.
The International Meteor Organization places the shower’s expected traditional maximum between Aug. 12 and 13 and lists a theoretical zenithal hourly rate of 100. That figure describes idealized observing conditions and should not be interpreted as a promise that an individual observer will see 100 meteors in an hour.
The timing is especially favorable because Wednesday’s New Moon is the same Moon that produced the Aug. 12 total solar eclipse, visible in totality from portions of Greenland, Iceland and Spain and as a partial eclipse from parts of the United States.
Perseids are produced when Earth encounters debris left by Comet 109P/Swift-Tuttle. The American Meteor Society says the particles enter the atmosphere at approximately 59 kilometers per second, or about 37 miles per second.
For Unknown Country readers, tonight also presents an unusually useful exercise in sky identification.
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A meteor generally appears suddenly, moves rapidly and disappears quickly. Perseids can also produce conspicuously bright fireballs; NASA has described the shower as particularly rich in bright meteors and fireballs.
Satellites behave differently, according to Space.com. They generally move much more slowly and can remain visible across a substantial portion of the sky. Reflected sunlight can also cause a satellite to brighten and fade, occasionally producing an initially puzzling sight.
Bright planets, aircraft and artificial satellites should therefore be considered before an observation is classified as genuinely anomalous.
But identification is easier when observers preserve more than an impression.
If you see something that does not behave like a meteor, satellite or aircraft, record the exact time, direction, duration, apparent motion and weather conditions, along with whether anyone else independently saw it. Note changes in brightness, direction or speed. Video can help, but contextual observations can be just as important when investigators later try to reconstruct what occurred.
August 12, the known sky should be unusually active. Knowing what belongs there may make whatever does not fit considerably more interesting.
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