Amateur astronomers may have spotted the second interstellar object ever found

Rodiano Bonacci
Settembre 13, 2019

The first was a cigar-shaped comet dubbed Oumuamua - a name of Hawaiian origin meaning a messenger from afar arriving first - that sailed into our planetary neighbourhood in 2017, prompting initial speculation that it may have been an alien spacecraft.

Comet C/2019 Q4, in contrast, is the kind of interstellar candidate that the European Space Agency (ESA) hopes to study via a mission called Comet Interceptor in just a few years. Scout is created to flag any asteroids that may pose a hazard to the Earth, but it can also flag potential interstellar objects, like C/2019 Q4. But it may turn out to be something much more exciting: the second known object to hurtle through our solar system after leaving another system. This will mean that we will have a lot more time to study it. "C/2019 Q4 (Borisov), meanwhile, is still approaching our Solar System and shouldn't reach perihelion until 10 December", the BBC reports.

Do we know what C/2019 Q4 looks like? No. The dust could make C/2019 Q4 simpler to track than 'Oumuamua, since dust brightly reflects sunlight.

This could also allow scientists to more easily study the object's composition, since telescope instruments can "taste" light to look for chemical signatures.

Such a statement is issued on behalf of the International Astronomical Union by the Smithsonian Astrophysical Observatory when observers have registered enough data about an object to begin calculating its path through space. In order to get the most accurate trajectory, astronomers need to have multiple days, ideally weeks, between measurements. But the current measurements of C/2019 Q4's trajectory suggest that such an encounter in the object's past is impossible. "It's the next-best thing to sending a probe to a different solar system", Hainaut said.

Initially, scientists thought C/2019 Q4 could be one of these objects, but with more observations, it's looking more and more like C/2019 Q4 is interstellar. It may pass between the orbits of Jupiter (purple) and Mars (orange) in late October.

The basic plan for Comet Interceptor is that it'll be launched to LaGrange point 2, a point where the gravity of the Earth and sun essentially cancel each other out.

The comet is now 260 million miles (420 million kilometers) from the Sun and will reach its closest point, or perihelion, on December 8, 2019, at a distance of about 190 million miles (300 million kilometers).

Comet C/2019 Q4 as imaged by the Canada-France-Hawaii Telescope on Hawaii's Big Island on September 10, 2019.

Hyperbolic orbits is an eccentric one.

While 'Oumuamua wasn't seen until it was on its way out of the solar system, C/2019 Q4 is still on its way in - and should remain visible for a year. There are over hundreds of known comets with hyperbolic orbits that have originated in the Oort Cloud, an icy group of leftover material on the outer edge of the solar system. C/2019 Q4 is now positioned close to the sun - which places it close to Earth's horizon and gives astronomers a very limited window of time before dawn to study it.

If these objects come every couple of years, on the other hand, astronomers might even be able to get choosy about which object to intercept.

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