Picture: www.imerisia.gr
A new meteor shower, the Leonids, will conquer the skies over Greece in the coming days, in two waves, which is not common. Astronomers expect a peak of "falling stars" in the morning of 17 November, and the second peak is likely to happen at dawn on 20 November.
The Leonids had an impressive peak in 1998-2002, and have since appeared more moderately. This year, a moderate fall of meteorites is expected at a speed of approximately 72 km per second and approximately 10-15 meteorites per hour. Observers will be able to see them if it is not cloudy.
This meteor shower comes from the constellation Leo, after which it is named, although in fact these are dust trails left by the tail of the comet Tempel-Tuttle, which crosses the Earth's orbit periodically. The comet, like almost all other comets, falls apart gradually and thus a moving stream of debris is created which is millions of kilometres wide and hundreds of millions of kilometres long. When the debris of the comet, which often weigh less than one gram, meet the upper atmosphere at an altitude of 80 to 130 km, the friction ignites them. Burning ionizes the surrounding atmosphere, creating a bright orb of 2 to 3 metres, which is seen from the Earth and is called a shooting star or a meteor.
The comet Tempel-Tuttle orbits the Sun every 33 years. The peak of the meteors from 1998-2002 is a result of the fact that then the orbit of the comet approached the Earth, resulting in the appearance of hundreds and even thousands of meteors per hour (a real storm of shooting stars). This year, the comet will be quite far, near the orbit of Uranus, and there will only be 10-15 shooting stars per hour.
According to Dionisis Simopoulos, Director of the Eugenides Foundation Planetarium, more than 100 tons of fine cosmic dust fall on the Earth's surface every day without being felt by people. The biggest storm of falling meteors observed in history was in 1833, when they looked like fireworks at a speed of dozens of meteors per second and lasted for hours. In 1878, a historian notes this shower as one of the 100 most important events in the USA and certain sociologists attribute the following spread of religious obsession in the United States to this celestial phenomenon.
The appearance of the Leonids in 1866 reached 5,000 shooting stars per hour. Temple-Tuttle was lost for an extended period, and it was believed that it had fallen apart. It was discovered back in 1965, when it crossed the Earth's orbit at a distance slightly farther than that of the Moon. On 17 November, 1966 in the central and western states of the United States, tens of thousands of shooting stars filled the sky for at least 20 minutes at a rate of 200,000 to 1 million per hour.