An enormous planet containing 10 times the mass of the Earth could explain the unusual orbit of a newly discovered asteroid. If found, the giant world would represent the first discovery of a planet in our solar system since Pluto in 1930, and before that Neptune in 1846. (Pluto was subsequently downgraded from planet to “dwarf planet” in 2006.)
The asteroid in question is called 2015 BP519. It was discovered three years ago at fifty-five times the Earth’s distance to the sun. Since that time, a group of astronomers led by Juliette Becker of the University of Michigan have been tracking it.
