Neptune's hidden trailing Trojans just doubled — they photobombed a telescope's test run

Some asteroids travel with Neptune around the sun, gathered in two loose clouds — one ahead of the planet, one behind it, each holding its place 60 degrees away. Astronomers had found 30 in the leading cloud but only two in the trailing one, which has spent 15 years crossing the bright star fields of the Milky Way, hiding its faint members like, in one researcher's words, needles in a sequined dress. Now a team led by Meg Schwamb of Queen's University Belfast has picked through test images from the Vera C. Rubin Observatory in Chile — taken while engineers were still commissioning the telescope — and found two more trailing Trojans, plus a third candidate, doubling the known trailing group. The newcomers look similar in makeup to the leading group, just as theories of how the solar system formed predict, and the team expects hundreds more of these ancient building blocks to turn up over Rubin's ten-year survey.