On the heels of the strange asteroid 'Oumuamua, comes another visitor to our solar system. This guest has been here for awhile – quite awhile in fact. The "exo-asteroid" known as 2015 BZ509 (seen in yellow circles in this negative image) is estimated to have arrived in the salad days of our solar system-- some 4.5 billion years ago.
Unlike the weirdly shaped 'Oumuamua who was just passing through, 2015 BZ509 became a permanent resident after being captured in Jupiter's orbit. The "interstellar immigrant," the subject of a new study, has a puzzling retrograde orbit, moving around the sun in the opposite direction of Jupiter, Space.com reports.