According to new research, all comets might come from the same place. Astronomer Christian Eistrup from Leiden University used chemical models on fourteen widely known comets only to find a clear pattern.
Comets move through the solar system and they are made of dust, ice, and small rocks. Their nuclei can span as wide as several kilometers. Some of them have strange orbits around the Sun and have also hit Earth in the past. Eistrup said that the composition of comets is very well known and are usually considered as icy balls. So he wanted to find out if they actually belong to one group or are divided by several subsets.
Eistrup’s research team also included Ewine van Dishoeck, Kavli Prize winner who created models for predicting the chemical composition of protoplanetary discs, which are flat discs made of dust and gas encompassing younger stars. These discs help in knowing about the formation of stars and planets. These were now applied to comets. Ewine along with Eistrup used statistics to understand if there was a particular place in the solar system where the models meet the comets’ data. It turned out that all the fourteen comets showed the same result. Each comet could be described by only one model indicating that their common origin. The work can be found here.
The origin is near to our Sun at a time when a protoplanetary disc encircled it while the formation of the planets took place. The model suggests a zone that is farther from the Sun’s nucleus and where the temperature varies in the range of 21 to 28 Kelvin, a very low temperature where CO (carbon monoxide) turns into ice. There are several reactions that are taking place in the ice phase in the time frame of a hundred thousand to million years. This explains different comets with different types of compositions.
The orbits of the comets vary since some of the comets might have been disturbed by planets like Jupiter, which explains the varied nature of the orbits.
Eistrup wants to test the hypothesis on many more comets as the current sample size is pretty small, only fourteen. He hopes that astronomers studying the solar system and its origins can use his results which can provide them with new insights, hence he is interested to discuss this model with other comet researchers.
We still do not how life started on our planet. However, the chemistry of the comets could be responsible for some of life’s building blocks. Life could start with the right comet hitting the right planet accompanied by a suitable environment. Understanding comets could lead to understanding the origin of life on our planet.