Comet's 2014 Mars Flyby Caused Most Intense Meteor Shower Ever Recorded

By Mike Wall, Space.com Senior Writer | September 21, 2017 

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An artist’s illustration of the Martian meteor shower caused by Comet Siding Spring’s flyby of the planet on Oct. 19, 2014. The comet has passed Mars in this view and is shown heading back toward the outer solar system. Mars’ atmosphere is exaggerated in this illustration to highlight the presence of a coherent group of meteors due to the comet’s debris stream.The annual Perseid meteor shower may be great, but it's got nothing on the brief sky show a comet gave Mars a few years back.Comet Siding Spring produced the most intense meteor shower in recorded history when the object flew by the Red Planet in October 2014, according to newly analyzed data collected at the time by NASA's Mars Atmosphere and Volatile Evolution (MAVEN) orbiter.

MAVEN'S observations suggest that the Siding Spring shower boasted about 108,000 meteors per hour at its peak and lasted up to 3 hours, scientists led by Matteo Crismani, of the University of Colorado Boulder, reported today (Sept. 21) in a presentation at the European Planetary Science Congress 2017 (EPSC 2017) in Riga, Latvia. 

For comparison, viewers with dark skies can usually count on seeing about 80 meteors per hour during the mid-August peak of the Perseid meteor shower, which is perhaps the most famous and reliably impressive of Earth's annual showers.The Perseids and other such showers occur every year when our planet plows through streams of debris shed by comets over the eons. Each shower is caused a particular debris stream. (In the Perseids' case, this debris comes from Comet Swift-Tuttle.)

The Siding Spring Martian shower, however, was a one-off event. The comet zoomed within 87,000 miles (140,000 kilometers) of the Red Planet's surface on Oct. 19, 2014, sending huge numbers of particles careening into the thin Martian atmosphere.

"This is one of the most exciting planetary events that we'll see in our lifetime," Beatriz Sanchez-Cano, of the University of Leicester in England, said in a statement. "Mars was literally engulfed by the coma, the comet's outer atmosphere, for several hours."

Scientists therefore observed the flyby using a number of instruments, including the spacecraft orbiting the Red Planet and roving across its surface. (MAVEN arrived just in time for the show, entering orbit around Mars in September 2014.)

Reproduced from space.com