A group of Spanish astronomers published a paper in the journal “Monthly Notices of the Royal Astronomical Society” that describes the greatest impact on the Moon ever recorded. It took place on September 11, 2013, when a meteorite the size of a car has caused an impact that generated a flash of light detected by the MIDAS (Moon Impacts Detection and Analysis System) system.
On September 11, 2013 Professor Jose Maria Madiedo of the University of Huelva was working with two telescopes in the south of Spain used to look for impacts of that type. It was early evening in Spain when in the lunar area called Mare Nubium (Sea of clouds) he noticed a flash of light very intense and prolonged.
Those impacts occur at very high speeds on the Moon because the atmosphere is almost non-existent so the meteorites are not slowed down. The consequence is that in the area of the impact the rocks are instantly melted and even partially vaporized. This produces a flash of light, which usually lasts for just a fraction of a second. On September 11, 2013, the flash was far more intense and longer than normal, more than ever observed before.
Professor Jose Maria Madiedo and his colleague Dr. Jose L. Ortiz of the Institute of Astrophysics of Andalusia have specialized in the study of lunar impacts and estimated that the meteorite that hit our satellite on September 11, 2013 had a mass around 400 kg (about 880 lbs.) and a diameter between 60 and 140 cm (between 2 and 4.5 feet). Upon impact its speed was around 61,000 km/h (about 37,900 mph) and created a crater with a diameter of about 40 m (about 130 feet). The impact energy is equivalent to that of 15 tons of TNT.
The video created to illustrate the event brings together images and animations. The Earth has the protection of its atmosphere, which destroys many meteorites before they can do damage and fragments others. However, a few days ago there was the first anniversary of the explosion of a meteorite on the Russian city of Chelyabinsk to remind us that the planet is always in danger.
Studies of lunar impacts are part of an increasing number of initiatives that deal with many more or less dangerous asteroids that cross the Earth’s orbit. Luckily, the one on September 11, 2013 happened on the Moon but the more and more sophisticated instruments we have available are revealing more and more asteroids that pass close to the Earth.
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