American astronomers have discovered that long-period comets, whose core in diameter reaches at least a kilometer, is about seven times larger than previously thought.

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Specialists also calculated that the long-period comets (that is, the period of revolution around the celestial body of 200 years) are on average twice as large as similar celestial bodies, whose motion is determined by the gravitational influence of Jupiter. The last objects revolve around the Sun with a period of about 20 years.

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Specify the number of authors succeeded after the data obtained by the infrared telescope WISE were analyzed. Specialists were the first to estimate the size of the nuclei of long-period comets, which, as a rule, are hidden by a coma - the foggy gas-dust envelope of the celestial body.

The chemical composition of comets has practically not changed since the formation of the solar system. Part of the water hit the Earth, probably from these celestial bodies. Their research allows us to understand the early history of the planet.