Near-Earth Asteroids are Spectacularly Destroyed Before Reaching the Sun

Some strange asteroid observations may just be explained by their destruction. Scientists have created a state-of-the-art model of near-Earth asteroids (NEOs0 and have found that most NEOs are destroyed before they ever get close to the sun.

The vast majority of NEOs originate in the doughnut-shaped main asteroid belt between the orbits of Mars and Jupiter. The orbit of a main-belt asteroid slowly changes as it is pushed by the uneven release of excess solar heat from the asteroid's surface. The asteroid's orbit eventually interacts with the orbital motions of Jupiter and Saturn changing the trajectory to bring the asteroid close to the Earth. An asteroid is classified as an NEO when its smallest distance from the sun during an orbit is less than 1.3 times the average Earth-Sun distance.

In this latest study, the researchers used the properties of almost 9,000 NEOs detected in about 100,000 images acquired over 8 years by the Catalina Sky Survey (CSS) to construct a new population model.

Surprisingly, it seemed as if the model had a problem; it predicted that there should be almost 10 times more objects on orbits that approach the sun to within 10 solar diameters. The scientists then spent time verifying their calculations before realizing that the problem was not in their analysis, but in their assumptions of how the solar system works.

The researchers found that their model would better match observations if NEPs are destroyed close to the sun, but long before actual collision. Calculating this in, the scientists found an excellent agreement between the model and observed population of NEPs when they eliminated asteroids that spent much time within about 10 solar diameters of the sun.

"The discovery that asteroid must be breaking up when they approach too close to the sun was surprising and that's why we spent so much time verifying our calculations," said Robert Jedicke, one of the researchers, in a news release.

The findings are published in the journal Nature.

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