It is not every comet that causes detectable meteor showers from Earth. But in recent years, NASA’s low-light video camera network, CAMS (Cameras for Allsky Meteor Surveillance), which specializes in observing the night sky has been expanded and, along with other video networks, has increased the orbit database of meteors to more than 2.2 million. This increased the cataloged number of meteor showers associated with long-term comets.
The meteor stream from comet Thatcher.Source: P. Jenniskens / SETI Institute / Reproduction
How meteor showers form
Meteor showers are the result of the accumulation of debris from comets along paths that repeat themselves through the solar system and then burn in the Earth’s atmosphere when we cross this dust trail. Many occur annually and are already part of the annual sky watcher calendar. Long-term comets, on the other hand, take more than 250 years to orbit the sun – an average of 400 to 800 years.
Typically, a shorter orbit means that a comet retraces its path more regularly, scattering meteors that can become more “shooting stars” when the Earth drags them into the orbit. This means that it is difficult for sky watchers to notice meteor showers caused by comets with orbits beyond 250 years.
“Until recently, we knew that only five long-period comets were the parent bodies of one of our meteor showers,” said Peter Jenniskens, meteor astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute and lead author of the new research, in a statement. . “But now we have identified nine more, and maybe even 15,” he said.
This kind of long-period comet can be linked to a specific meteor shower, as scientists did with Comet C / 2002 Y1 Juels-Holvorcem and the rain UY Lyncids, who spend only once every 3,967 years in the sun’s orbit. To give you an idea, the comet C / 2002 Y1 Juels-Holvorcem made an approximation of the sun in 2003 – which means that his last visit was around 2,000 BC and that his next passage near the sun will not occur until almost 6,000.
Meteor showers and their parents
The longest-known comet most likely to trigger a meteor shower is the C / 1861 G1 Thatcher, which causes the meteor shower Lyrid, in April. The rains of other long-term comets are less dramatic – even those that have been identified previously, such as Aurigids (comet debris C / 1911 N1 Kiess) and Leonis Minorids (from comet C / 1739 K1 Zanotti).
The team behind the new study wanted to find more such connections – that was when the partnership with the CAMS project appeared, which includes observation stations in the United States and around the world, in places like New Zealand, Namibia, Chile and the Emirates. United Arabs – totaling more than 500 individual cameras, all looking for meteors.
“These are the shooting stars that you see with the naked eye,” said Jenniskens. “Tracing their direction of approach, these maps show the sky and the universe around us in a very different light,” he said. With such a large catalog of meteor sightings, scientists can now identify subtle meteor showers based on tracking just a few shooting stars at similar points of origin in the sky – called radiant.
Map of some meteor showers.Source: Space.com/Reprodução
Astronomers combined the analysis of a decade of observations with NASA’s database of comets and their orbits and found at least nine new combinations between meteor showers and long-term comets – and identified six other potential combinations. The survey also tracks comets responsible for meteor showers like Sigma Virginids December and Pegasids July, caused by debris from C / 1846 J1 Brorsen and C / 1979 Y1 Bradfield respectively.
Although most of the surveyed comets pass through the Sun every 400 to 800 years, scientists have linked some other long-period comets to specific meteor showers – but have not been able to define their orbital periods.
Among the meteor showers studied, an intriguing trend was found: long-term comet displays tend to last for several days, and the radiant appears to move like a spot in the sky. Scientists believe that the effect may be caused by the orbit of a comet changing between loops, so that the debris fields do not line up as clearly as in short-term comets.
“It was a surprise for me,” said Jenniskens. “This probably means that these comets have returned to the solar system many times in the past, while their orbits have gradually changed over time,” he concluded.