Neptune’s mysterious, far-flung moon Nereid may be the last of the planet’s original companions. Scientists at the California Institute of Technology reported Wednesday that they used NASA’s Webb Space Telescope to study the moon in 2024. Their observations suggest Nereid is no party crasher like Neptune’s jumbo moon, Triton, which barged in from the solar system’s frigid outskirts billions of years ago. Triton’s arrival scattered the planet’s original moons and wrecked everything, but these researchers believe Nereid survived by escaping into its extreme, elliptical orbit around Neptune. Their findings appear in the journal Science Advances.