Passionate observers watching the January "super-blood wolf" may have observed two rare events for the price of one: a brief flash when a meteorite hit the surface of the Moon.
- Scientists believe the object was a comet weighing 45 kg and measuring up to 60 cm in diameter
- The energy of the impact of the comet was equivalent to 1.5 tons of TNT
- Monitoring the impacts of meteorites on the lunar surface helps scientists understand the risks they present to astronauts
Spanish astronomers reported that a space rock struck the Moon at 61,000 kilometers during the eclipse, digging a crater nearly 15 meters in diameter.
It was the first so-called "flash impact" ever observed during a lunar eclipse, according to the results published in the monthly announcements of the Royal Astronomical Society.
Scientists – who run a lunar shock-sensing system using eight telescopes in Spain – believe the object was a fragment of a comet weighing 45 kilograms and measuring up to 60 centimeters in diameter.
The impact energy was apparently equivalent to 1.5 tons of TNT.
One of the authors of the study, Jose Maria Madiedo, said it was "really exciting" to capture the brief flash after many previous attempts.
Unlike the Earth, the Moon has no atmosphere to protect it, so even small rocks can hit its surface.
These rocks often hit at enormous speeds and are instantly vaporized, producing a flash of light debris that can be detected by the Earth.
While the detection system – dubbed MIDAS – has captured numerous lunar impacts since the end of the 1990s, this was "the first time ever that an impact flash was unequivocally recorded during an eclipse lunar and discussed in scientific literature ".
Multiple wavelengths of light were captured, producing a high-fidelity view of the impact of the meteorite on the surface of the Moon.
People watch the rise of the "super moon" behind the skyline of Los Angeles in central January. (AP: Ringo HW Chiu)
"The flash lasted 0.20 seconds and its peak brightness in the visible band was equivalent to the brightness of a star of magnitude 4.2," the report states.
Because it was easy enough to see, the impact "was also noticed by casual observers who were taking pictures of the eclipse," the study said, some of whom published their observations online.
The user of Reddit, ahecht, said at the time: "I saw a bright glow on the moon in front of the remaining fragment of the sunset … just before the beginning of totality.
"I ran inside and checked (a Moroccan webcast of the eclipse) and it was visible there too, so it wasn't an airplane or something else.
"Could it have been a meteor impact on the moon?"
YouTube user Clifton Kern has posted a video recorded in Pennsylvania during the eclipse – the flash is visible in the lower left corner on the Moon at 2:11:01.
According to the study, the Earth and the Moon are constantly affected by meteorites and the collision analysis provides valuable data for scientists.
It can often be difficult however to see the impact flash, depending on the brightness of the light emitted during the collision of a meteor with the surface of the Moon.
Since most flashes are very weak, they must be recorded against a dark background, so scientists try to capture them happening on the "dark side" of the Moon.
The Moon is seen rising behind the Empire State Building before the eclipse. (AP: Julio Cortez)
Supermoon or superbuzz?
This lunar eclipse occurs more than a day after the Moon has approached the Earth in this orbit. This simply makes it a "supermoon" – the third in three months – based on a loose definition coined for the first time by an astrologer.
But it's hard to tell the difference between a supermoon, even at its closest, and a regular full moon, says Tanya Hill of the Melbourne Planetarium.
"C & # 39; it's a small difference, but it's not something we can see or relate to the night sky.
"The & # 39; supermoon & # 39; is just a little 'superbuzz," he says.
Find out more in our Beginner's Guide to the Moon.
There are only about 10 days a month in which it is possible to capture lightning, during the rising and falling phases of the Moon – or during lunar eclipses, such as that occurred on January 21st of this year.
But lunar eclipses do not last long, and it can be difficult to pinpoint the impact of the dimmer, depending on how bright the eclipse is.
These and other factors may have contributed to the fact that, although several researchers have previously attempted to capture impact flashes during lunar eclipses, none have succeeded so far.
Professor Madiedo said in a statement that he was impressed when he observed the event because it was so bright and added "something inside me told me this time it would be now".
"It would be impossible to reproduce these high-speed collisions in a laboratory on Earth: observing flash is a great way to test our ideas on exactly what happens when a meteorite collides with the Moon," he said.
The team will continue to monitor the impacts of meteorites on the lunar surface to help them understand the risk they face astronauts intending to return to the moon over the next decade.
ABC / wires
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