A particularly bright meteor seen in Earth’s skies on July 31 was tracked from a comet that created a debris field as it began to break apart thousands of years ago.
Scientists believe that the fragment, which ended its life as a fireball over Madrid, Spain, began as part of comet 169P/NEAT, which formed at the same time as the solar system, about 4.6 billion years ago. The comet, an icy body that sheds debris as it travels, is responsible for the annual Alpha Capricornis meteor shower, which first occurred between 3,500 and 5,000 years ago when about half of comet 169P/NEAT broke apart.
Although the small fragment and the light show created as it disintegrated in Earth’s atmosphere posed no danger, the European Space Agency (ESA) said in a statement. (will open in a new tab) that the meteor is a “cautionary tale.” This is because streams of tiny fragments are left by larger bodies that once passed close to our planet and may do so again.
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When a comet’s near-icy body passes the Sun, its ice immediately begins to turn into gas in a process called sublimation. Sublimation ejects into space a stream of ancient material—unchanged since the dawn of the solar system—that lingers in space.
On July 31, this particular fragment, thought by astronomers to be about 4 inches (10 centimeters) across, began burning brightly in Earth’s atmosphere about 60 miles (100 km) above Madrid. It burned out by the time it reached about 48 miles (77 km) over the province of Guadalajara.
Scientists tracked the fireball’s trajectory using footage captured by the ESA-operated AllSky7 camera network in Cebreros, Spain, as well as cameras operated by the Southwest European Meteor Network (SWEMN) and other ground-based cameras throughout Europe. These observations allowed the SWEMN researchers to trace the meteor back to its origin, showing that it originated from the same source as the Alpha Capricornida meteor shower.
This meteor shower can usually be seen in the sky between July 7 and August. 15 every year. Although Alpha Capricornids produce only infrequent meteors—at their peak, about five meteors per hour—they can be very bright, often turning into fireballs.
However, this season, future skywatchers will be able to catch more fireballs. Scientists expect the Alpha Capricornis meteor shower to get stronger in the coming centuries as more of the material left behind by the comet drifts into Earth’s orbit. By 2220, Alpha Capricornids will be stronger than any current annual meteor shower the Earth experiences, according to the ESA.
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