The 2I/Borisov comet, the second interstellar object ever observed, will make its closest approach to Earth on Saturday, December 28, on its way through our solar system, according to NASA.2I/Borisov is the first comet ever observed from outside our solar system and only the second interstellar object every observed. The first observed interstellar object was Oumuamua, a rod-like object which was only briefly observed. 2I/Borisov was observed early, allowing astronomers to study the interstellar visitor in depth.“Nothing about Borisov is weird,” said Dr. Gregory Laughlin, a Yale astronomer, to The New York Times. “With Oumuamua, everything was weird.”The comet will pass through the constellations Crater and Hydra as it passes 180 million miles from Earth. As a reference, that's twice the distance between the Earth and the Sun. The comet will be too dim to see without a telescope, and will even be a challenge in fairly large amateur instruments, according to NASA.2I/Borisov was named after the Crimean amateur astronomer who first spotted the comet on August 30, Gennady Borisov. Observations of the comet have found that the nucleus is over 15 times smaller than earlier investigations suggested, with a radius of less than half a kilometer (0.3 miles). The chemical composition of the comet is similar to comets found within our solar system. The comet's tail is 100,000 miles (160,000 kilometers) long, about 14 times the diameter of Earth.As the comet is moving at around 100,000 mph, the sun cannot capture it in its orbit. It will reach Jupiter by the middle of 2020.