Before dawn on August 30, an amateur astronomer named Gennady Borisov spotted an alien visitor: a comet from beyond the confines of our solar system. That object, now named 2I/Borisov, is just the second confirmed interstellar object ever detected inside our cosmic neighborhood.

Now, as large telescopes around the world turn their gaze toward Borisov, astronomers are beginning to glean tantalizing clues about the comet’s composition and its track through the heavens. Each new data point reveals a bit more about the chemistry of Borisov’s home star system and, in turn, how unique our own solar system is within the cosmos.

The first known interstellar interloper, a comet called ‘Oumuamua discovered in 2017, wasn’t found until it was already headed