Free Astronomy Magazine November-December 2023

21 NOVEMBER-DECEMBER 2023 T his video shows the paths through our Solar System of the two confirmed interstellar objects, 'Oumuamua (formally known as 1I/2017 U 1 ), discovered in 2017, and the comet 2I/Borisov, discovered in 2019. The paths of these objects are markedly different than the orbits of objects in our Solar System, making them easy to differentiate as inter- stellar objects. Rubin Observatory and the Legacy Survey of Space and Time will provide data that enables scientists to identify many interstel- lar objects early in the survey. [Rubin Observatory/NSF/AURA/J. Pinto] our Solar System right now,” said Ban- nister. “We just can’t find them yet be- cause we aren’t see- ing faint enough.” Rubin Observatory will change that. Using an 8.4-meter telescope equipped with the highest res- olution digital cam- era in the world, Rubin will detect fainter interstellar objects than we’ve ever seen before. “It’s as though you suddenly go from being on a little boat bobbing around in the beautiful shal- lows just off the shore, to now you’re out over the big deep ocean and you can see into all that expanse for the first time,” said Bannister. Additionally, Rubin’s fast-moving tele- scope can scan the entire visible sky ev- ery few nights, capturing a time- lapse view of interstellar objects on “We calculate that there are a whole lot of these little worlds in their fast journeys through our Solar System. While we call both ‘Omua- mua and 2I/Borisov interstellar ob- jects, they differ in just about every way we can measure. What will the third, or the twentieth, interstellar object look like? Within the first year of Rubin Obser- vatory’s 10-year LSST, scheduled to begin in 2025, scientists expect to get a good idea. “We’re going to go from a study of two individual ob- jects to a population study of at least dozens,” Bannister said. As interstellar objects could come from stars all across the Milky Way, this increase will allow scientists to directly study how planetary systems form at distant stars throughout our galaxy’s history — including at an- cient stars that no longer exist. For now, scientists can only make loose predictions of how many inter- stellar objects Rubin will reveal. Ban- nister playfully places her bet on 21, but says we really have no idea yet. Whatever the outcome, Rubin is poised to revolutionize Solar System studies — along with many other areas of astronomy and astrophysics. “It’s going to be one of the gifts that Rubin provides,” she said, “a new history of the Solar System and a greater understanding of where we come from.” !