The astronomy community has been buzzing since astronomer Gennady Borisov, from Crimea, made the remarkable discovery of the second known interstellar object to have passed into our solar system – a comet labeled C/2019 Q4 . This object has left scientists surprised, yet satisfied with how easy it was to uncover its identity. Although some questions still have yet to be answered, such as the object’s size and shape, recent follow-up images taken by the Gemini Multi-Object Spectrograph at the Gemini North Telescope located in Hawaii, reveal that this cosmic visitor is most definitely a comet from another solar system.
The Gemini image, along with similar observations from other telescopes, show that the comet is moving at a very fast speed, which indicates that it is a long way from home, as objects residing in our solar system follow a set trajectory at much slower speeds. More concrete data shows that the comet has an eccentricity of 3.7. A higher eccentricity means a more elliptical orbit, but any eccentricity above one indicates that the body in question is not orbiting the sun, confirming that it is definitely out of the ordinary.
But how do we know whether this lone traveler even is a comet? First we must think about what comets actually are. They are essentially the fragments left over from the birth of stars and planets. These cosmic rejects, if you will, are released during the formation process and can sometimes travel as far as other solar systems. Through observational data we can tell whether or not the object is a comet by looking for a gas and dust halo around it which is illuminated by the sun. Telescope images of C/2019 Q4 clearly depict this.
This discovery is all the more interesting when compared to the first one made in 2017. The discovery of the object ‘Oumuamua goes down in history as the first time scientists had seen an object from another solar system. However, despite the excitement surrounding this fortunate sighting, astronomers caught the object as it was leaving our solar system. It was thus fading away which had scientists scrambling to obtain any useful data from it. Unlike ‘Oumuamua, we managed to catch C/2019 Q4 as it was entering our solar system. It will gradually get brighter as it gets closer to the sun, which is great news because it gives scientists ample time to extract observational data from the object.
Now that scientists have made this remarkable discovery, they have their hopes set on attaining valuable information from it. Researchers aim to measure the chemical composition of C/2019 Q4 and compare it with that of comets in our home solar system, to spot any striking similarities or differences in composition. Additionally, astronomers hope to obtain better images of the comet as it gets closer to Earth, to get a clear path of its orbit and confirm that it does, in fact, come from another system.
This comet is an ephemeral existence here in our solar system; before we know it our visitor will have left us in search of its next destination. Though while it is still here, we will take the opportunity to learn as much from it as we possibly can.
Written by Carli Smith and edited by Tara Wagner-Gamble