Rosetta Comet was shaped from two different bodies with an appearance similar to a rubber ducky

From the time the Europe’s Rosetta probe landed on the surface of a comet last year, experts have been perplexed on the rubber duck shape of the comet. So far researchers were able to conclude that the bizarre shape appeared due to localized erosion on the surface of Comet 67P/Churyumov-Gerasimenko or perhaps the merger of two comets.

However, a study in Nature on Monday deduced that it was actually a collision that caused the comet’s unique, double-lobed appearance. The European Space Agency’s Rosetta probe surfaced on the comet in November 2014. Therefore, the mission is considered to be the first successful attempt to land on a frozen remnant of the solar system’s birth.

With the means of high-resolution pictures shot between August 6, 2014 and March 17, 2015, researchers were able to study the layers of material which was visible all over the nucleus. It displayed that the shape arose from a low-speed collision within the two fully fledged, separately formed comets.

How the comet acquired its probing shape has been the foremost query since we first saw it,” stated Holger Sierks, of the Max Planck Institute for Solar System Research in Göttingen and principal investigator with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), the main imaging system of the Rosetta mission. “As of now, we are grateful for this detailed study, through which we can assert with certainty that it is a contact binary.”

To get to their conclusion, scientists initially used imageries to categorize over 100 terraces seen on the surface of the comet, and parallel layers of material clearly viewed in bare cliff walls and pits. A 3D shape model was then applied to regulate the guidelines in which they were sloping and to visualize how they spread over the subsurface.

“We infer that the gentle, low-velocity collisions took place within the two fully formed kilometre-sized cometesimals (mini-comets) in the early stages of the Solar System”, which was formed nearly 4.6 billion years ago, the scientists said. The evidence which the scientists detailed was found in the differences between the onion-like layers of the two lobes.

“These two bodies must have collided very sluggishly and merged very slowly otherwise we would not be able to see this ordered (onion-like) structure,” team member Matteo Massironi stated in a webcast press briefing on Monday.

As the collision rooted the shape, the team originated that erosion might have played a minor role, and it is definitely a significant one.

Local variations observed in the structure of the surface mostly resulted from the different rates of sublimation - when ice directly converts into a gas - of frozen gases surrounded within the individual layers that are not necessarily dispersed evenly throughout the comet.

“This effect enhances our growing knowledge of the comet — how it is formed and its evolution,” Rosetta project scientist Matt Taylor said.

He concluded by saying, “Rosetta will keep observing the comet for another year in order to receive the maximum amount of data on this celestial body and its place in the history of our solar system.