Fragment Believed To Be Part Of The Earth's Formation Came Back After Billions of Years

First Posted: May 02, 2016 06:30 AM EDT

Astronomers have found a unique object that might be from an inner solar system material from the time of the Earth's formation billions of years ago. According to experts, C/2014 S3 (PANSTARRS) is the first object to be discovered on a long-period cometary orbit that has the characteristics of a pristine inner solar system asteroid. It may help understanding how the solar system formed.

The study's lead author, Karen Meech of the University of Hawai'i's Institute for Astronomy and her colleagues have concluded that C/2014 S3 (PANSTARRS) was formed in the inner Solar System at the same time as the Earth itself, but was ejected at a very early stage.

Science Daily explained that the researchers' observations show that it is an ancient rocky body rather than a contemporary asteroid that strayed out. It is one of the potential building blocks of the rocky planets, such as the Earth, that was expelled from the inner Solar System and preserved in the deep freeze of the Oort Cloud for billions of years.

Karen Meech explained the unexpected observation saying, "We already knew of many asteroids, but they have all been baked by billions of years near the Sun. This one is the first uncooked asteroid we could observe: it has been preserved in the best freezer there is."

C/2014 S3 (PANSTARRS) was originally identified by the Pan-STARRS1 telescope as a weakly active comet a little over twice as far from the Sun as the Earth. It's current orbital period (860 years) suggests it was nudged comparatively recently into an orbit that brings it closer to the Sun.

According to, the team immediately noticed that there was something different about C/2014 S3 (PANSTARRS). It does not have the characteristic tail that most long-period comets have when they approach so close to the Sun. Because of this, it has been known as a Manx comet, after the tailless cat. Within weeks of its discovery, the team obtained spectra of the very faint object with ESO's Very Large Telescope in Chile.

After careful study of the C/2014 S3 (PANSTARRS), the research team found that it is normal for asteroids known as S-type to have a light reflected in the inner asteroid's main belt. It does not look like a typical comet, which are believed to form in the outer Solar System and are icy, rather than rocky. It looked like the material has undergone very little processing, showing that it had been kept frozen for a very long time.

The authors conclude that this object is probably made of fresh inner Solar System material that has been stored in the Oort Cloud and is now making its way back into the inner Solar System. Co-author Olivier Hainaut (ESO, Garching, Germany), concluded saying, "We've found the first rocky comet, and we are looking for others. Depending how many we find, we will know whether the giant planets danced across the Solar System when they were young, or if they grew up quietly without moving much."

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