In 2019, amateur astronomer Gennadiy Borisov discovered a comet, which now bears his name. There’s a long history of amateur astronomers discovering comets, as they approach our inner Solar System on their elongated orbits. But this one was different: it was moving much too fast to be gravitationally bound to the Sun.
It was an interstellar comet. And now, it looks like it has split into two chunks.
When it comes to the challenges posed by interstellar travel, there are no easy answers. The distances are immense, the amount of energy needed to make the journey is tremendous, and the time scales involved are (no pun!) astronomical. But what if there was a way to travel between stars using ships that take advantage of natural phenomena to reach relativistic velocities (a fraction of the speed of light).
Already, scientists have identified situations where objects in our Universe are able to do this – including hypervelocity stars and meteors accelerated by supernovae explosions. Delving into this further, Harvard professors Manasvi Lingam and Abraham Loeb recently explored how interstellar spacecraft could harness the waves produced by a supernova explosion in the same way that sailing ships harness the wind.
On August 30th, 2019, astronomers with NASA, the ESA, and the International Scientific Optical Network (ISON) announced the detection of the interstellar comet C/2019 Q4 (2I/Borisov). News of the object was met with a great deal of excitement since it was only the second interstellar object to be detected by astronomers – the first being the mysterious object known as ‘Oumuamua (which astronomers are still unsure about)!
After a lot of waiting and several follow-up observations, 2I/Borisov is about to make its closest approach to Earth. To mark the occasion, a team of astronomers and physicists from Yale University captured a close-up image of the comet that is the clearest yet! This image shows the comet forming a tail as it gets closer to the Sun and even allowed astronomers to measure how long it has grown.
For over a century, proponents of Panspermia have argued that life is distributed throughout our galaxy by comets, asteroids, space dust, and planetoids. But in recent years, scientists have argued that this type of distribution may go beyond star systems and be intergalactic in scale. Some have even proposed intriguing new mechanisms for how this distribution could take place.
For instance, it is generally argued that meteorite and asteroid impacts are responsible for kicking up the material that would transport microbes to other planets. However, in a recent study, two Harvard astronomers examine the challenges that this would present and suggest another means – Earth-grazing objects that collect microbes from our atmosphere and then get flung into deep-space.
When the mysterious object known as ‘Oumuamua passed Earth in October of 2017, astronomers rejoiced. In addition to being the first interstellar object detected in our Solar System, but its arrival opened our eyes to how often such events take place. Since asteroids and comets are believed to be material left over from the formation of a planetary system, it also presented an opportunity to study extrasolar systems.
Unfortunately, ‘Oumuamua left our Solar System before any such studies could be conducted. Luckily, the detection of comet C/2019 Q4 (Borisov) this summer provided renewed opportunities to study material left by outgassing. Using data gathered by the William Herschel Telescope (WHT), an international team of astronomers found that 2I/Borisov contains cyanide. But as Douglas Adams would famously say, “Don’t Panic!”
When ‘Oumuamua passed through our Solar System two years ago, it set off a flurry of excitement in the astronomical community. Here was the first-ever interstellar object that be observed by human trackers, and the mysteries surrounding its true nature and composition led to some pretty interesting theories. There were even some proposals for a rapid mission that would be able to rendezvous with it.
And now that a second interstellar object – C/2019 Q4 (Borisov) – has been detected traveling through the Solar System, similar proposals are being made. One of them comes from a group of scientists from the Initiative for Interstellar Studies (i4is) in the UK. In a recent study, they assess the technical feasibility of sending a mission to this interstellar comet using existing technology, and found that there were a few options!
On August 30th, amateur astronomer Gennady Borisov spotted a comet of extrasolar origin passing through our Solar System. This is the second time in as many years that an interstellar object has been observed (the last being ‘Oumuamua 2.0 in 2017). Thanks to the Gemini Observatory, we now have pictures of this comet, making it the first object of its kind to be successfully imaged in multiple colors!
In 2017, astronomers and the world were surprised to learn that an interstellar object (named ‘Oumuamua) passed by Earth on its way to the outer Solar System. After multiple surveys were conducted, scientists were left scratching their heads as to what this object was – which speculation ranging from it being a comet or an asteroid to comet fragment or even an extra-terrestrial solar sail!
But one of the greatest takeaways from that event was the discovery that such objects pass through our Solar System on a regular basis (and some stay). And as it turns out, astronomers with NASA, the ESA, and the International Scientific Optical Network (ISON) announced the detection of what could be a second interstellar object! Could this be ‘Oumuamua 2.0? And if so, what mysteries might it present?
When ‘Oumuamua crossed Earth’s orbit on October 19th, 2017, it became the first interstellar object to ever be observed by humans. These and subsequent observations – rather than dispelling the mystery of ‘Oumuamua’s true nature – only deepened it. While the debate raged about whether it was an asteroid or a comet, with some even suggesting it could be an extra-terrestrial solar sail.
In the end, all that could be said definitively was that ‘Oumuamua was an interstellar object the likes of which astronomers had never before seen. In their most recent study on the subject, Harvard astronomers Amir Siraj and Abraham Loeb argue that such objects may have impacted on the lunar surface over the course of billions of years, which could provide an opportunity to study these objects more closely.
The ESA has announced a new mission to explore a comet. The Comet Interceptor mission will have a spacecraft wait in space until a pristine comet approaches the inner Solar System. Then it will make a bee line for it, and do some ground-breaking science.