Free Astronomy Magazine March-April 2025

25 MARCH-APRIL 2025 ASTRO PUBLISHING T his UHD image shows several ALMA antennas at the Llano Chaj- nantor. Above them, the bright Milky Way is visible. [ESO/Y. Beletsky] straightforward to find. And yet, the new observations indicate that they are infrequent. This means that ei- ther most belts form further out or smaller belts are less massive and, in fact, more complex to detect. The team also confirmed previous findings: as belts evolve, collisions within them smash their large ob- jects into smaller ones. If this process were to happen faster in belts closer to their stars, it could also explain why the team didn’t find small belts. Belts are more extensive than pre- viously thought and extend more widely. Think of a doughnut with a small hole rather than an onion ring. Narrower belts — called “rings” — are uncommon in the survey. One possibility is that belts broaden as time passes. The first results from this survey, though, found that older belts are not necessarily broader, in- dicating that this is probably not the case. Another possibility is that wide belts have gaps within them that would split them into narrower rings, but we can’t see this yet. This is not the end of the story of belts, though. Researchers think fu- ture telescopes can uncover sub- structures within belts, like gaps and rings. Belts could even hide dwarf planets, much like Pluto, ready to be discovered. But studying these belts is more than just searching for space treas- ures; it is also learning about the his- tory of our solar system and planet. Earth is always watching the Kuiper Belt, a significant source of aster- oids and comets. Since an asteroid caused a major extinction 66 million years ago, it is understandable why we would be concerned. However, one theory suggests that some of Earth’s water may have also arrived from the Kuiper Belt, a giant repos- itory of frozen water. Large far-away planets like Neptune or Uranus may have had a crucial role in propelling water-carrying comets toward us, providing an ele- ment that would otherwise be rare on the primitive Earth. Only time will tell whether we owe our lives to space rocks. As we learn more about exocomet belts, we may finally be able to understand the role that belts play in the formation and evo- lution of planetary systems. !