Perseids Peak Brilliantly Aug. 12 to 13, 2015, Thanks to Darkened Moon

Summary: The 2015 Perseids peak brilliantly Aug. 12 to 13 in the Northern Hemisphere's northeastern skies, thanks to the darkness of the new moon.

two Perseid meteors and their radiant (crossing of dotted line) in Perseus, with nearby constellation Andromeda: Brocken Inaglory, CC BY SA 3.0, via Wikimedia Commons

With its luminous designation as the second brightest celestial object -- after the resplendent sun -- in Earth’s skies, the moon tends to rule the night. Exceptions to nighttime supremacy include cloud cover and moon phase.

The new moon, which heralds the beginning of the eight-phase lunar cycle, is cloaked in invisibility for Earthlings. Only illumination by earthshine (earthlight reflected onto the moon’s night side) during a solar eclipse reveals the darkened silhouette of the new moon.

Earthshine also spotlights the edges of the waning and waxing crescent moons that respectively precede and follow each new moon. August 2015’s waning crescent decreases from 10 percent visibility on Tuesday the 11th to a scant 5 percent illumination on Wednesday the 12th. The new moon emerges Friday, Aug. 14, at 10:53 a.m. Eastern Daylight Time (2:53 p.m. Coordinated Universal Time), playing a stealthy game of hide-and-seek with a bare 1 percent visibility.

The phase of the moon frames or disrupts viewing of nighttime events such as meteor showers. In late July 2015, the full moon phase, in which the lunar surface presents full illumination for Earthlings, coincided with peak viewing of the Delta Aquarid meteor shower. Unable to compete with lunar brilliancy in clear skies, the Delta Aquarids faded into the night’s vastness.

Meteor showers are named according to the radiant, the point in space from which they seem to originate. The Perseids appear to come from the constellation Perseus, namesake of Greek mythology’s first hero, in the northern sky.

Cometary debris entering Earth’s atmosphere at extremely high velocities of over 35 miles (60 kilometers) per second, create meteor showers. Perseid debris forms a cloud stretching along the short-period, elliptical orbit of 133 years traced by its parent body, Comet Swift-Tuttle. Comet Swift-Tuttle was discovered independently, three days apart in 1862, by two American astronomers: on July 16 by Lewis Swift (Feb. 29, 1820–Jan. 5, 1913); on July 19 by Horace Parnell Tuttle (March 17, 1837–Aug. 16, 1923).

The Perseids occur annually between mid-July and late August. In 2015, peak activity, which prolifically showers meteors at 60 to 90 meteors per hour, is slated for overnight as Wednesday, Aug. 12, transitions to Thursday, Aug. 13.

The prominent shower starts around 9:30 p.m. EDT Tuesday evening (1:30 a.m. UT Wednesday), with the Northern Hemisphere favored for best viewing, especially from midnight to predawn hours.

When Jupiter passes closest to Comet Swift-Tuttle’s orbit, the solar system’s planetary behemoth nudges, via its mighty gravitational field, the comet’s meteoroid stream closer to Earth. Closeness injects a bloated swath of debris into Earth’s atmosphere within about 22 months and enhances the Perseid display.

Jupiter closed in on Comet Swift-Tuttle’s orbit in November 2014. While 2016’s Perseid shower is expected to achieve spectacular peaks estimated at possibly 120 meteors per hour, August 2015 easily may deliver above-normal fireworks as well.

Apart from cloud interference, the Perseids live up to annual reliability for shooting noticeably across the sky during peak viewing. Although binoculars, cameras with telescopic lenses and telescopes may not be rivalled for increasing immediacy, the Perseids provide an enjoyable, generous spectacle for naked-eye viewing.

All that is required for witnessing one of the most popular meteor showers is to look up, with or without optical aids, at the northeastern nighttime sky.

Perseid meteor shower as viewed from International Space Station, Aug. 14, 2011, over an area of China about 400 kilometers from Beijing: Ron Garan/Expedition 28, Public Domain, via NASA

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

two Perseid meteors and their radiant (crossing of dotted line) in Perseus, with nearby constellation Andromeda: Brocken Inaglory, CC BY SA 3.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Labeled-perseids.jpg

Perseid meteor shower as viewed from International Space Station, Aug. 14, 2011, over an area of China about 400 kilometers from Beijing: Ron Garan/Expedition 28, Public Domain, via NASA @ https://www.nasa.gov/mission_pages/station/multimedia/gallery/iss028e024847.html

For further information:

Kronk, Gary W. Meteor Showers: An Annotated Catalogue. The Patrick Moore Practical Astronomy Series. 2nd ed. New York: Springer Science + Business Media, 2014.

Rao, Joe. "Perseid Meteor Shower Gets a Boost from Dark Moon, Jupiter." Fox News > Air & Space. Aug. 11, 2015.
Available @ http://www.foxnews.com/science/2015/08/11/perseid-meteor-shower-gets-boost-from-dark-moon-jupiter/