Asteroids Are Destroyed Much Farther From The Sun Than Previously Thought

A new study finds asteroids blow up much farther away from the Sun than originally thought. The surprising conclusion helps explain puzzling results from a state-of-the-art model of 9000 near Earth objects (NEOs).

An international team of scientists lead by researchers at the University of Helsinki, created a first-of-its-kind model of NEOs using over 8 years of data from the Catalina Sky Survey (CSS). Upon completion, researchers realized there was a big inconsistency – the model predicted about 10 times more objects that reach within 10 solar diameters of the Sun. Scientists spent a year verifying their model showing it was consistent with the laws of physics as we know them. The team was simply stumped.


Artists impression of an unstable asteroid as it approaches the Sun. Image credit: Lauri Voutilainen

That is until Dr. Mikael Granvik, who is lead-author of the study published in the journal Nature, hypothesized that the asteroids were being destroyed much further away from the Sun than was commonly thought. Researchers tested the idea by tweaking the model and found it to be in almost-perfect agreement with actual observations of NEOs in our solar system.

“The discovery that asteroids 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 team member Dr. Robert Jedicke at the University of Hawaii Institute for Astronomy.

The study explains the mystery of lonely “streams” of debris astronomers have found in the past. A meteor usually consists of the main object followed by a stream of material. In the past decade, astronomers have observed several streams, but were unable to identify a parent object for many streams close to the Sun. The study suggests that the parent objects were destroyed all-together because they were too close to the Sun, leaving the lonely streams of debris behind.

But how are these asteroids being destroyed you might ask?


A map of the known asteroids of the inner solar system. Image credit: UK Space Guard Center/ Keck/ Caltech

The actual mechanism causing the destruction of asteroids close to the Sun is still unknown. Scientists think its likely that volatile materials inside the asteroid expand enough at moderate temperatures to blow up the body of the object.

Researchers also discovered that darker asteroids are destroyed further from the Sun than lighter asteroids. The fact that darker objects are more easily destroyed implies that dark and bright asteroids have a different internal composition and structure – and there’s likely more of the volatile material that causes the blow ups in the darker asteroids.

“Perhaps the most intriguing outcome of this study is that it is now possible to test models of asteroid interiors simply by keeping track of their orbits and sizes. This is truly remarkable and was completely unexpected when we first started constructing the new NEO model,” Dr. Granvik said.

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