Does our Oort Cloud overlap with Alpha Centauri’s?
Carles Martinez
Barcelona, Spain
About 2,000 to 5,000 astronomical units (AU; where 1 AU is the average distance between Earth and the Sun) from the Sun lies the beginning of the Oort Cloud. For context, the Voyager spacecrafts — the human-made objects that have traveled farthest from our Sun — will cross this inner edge of our solar system in about 300 years. From there, the Oort Cloud stretches to about 10,000 to 100,000 AU (0.16 to 1.6 light-years), according to NASA. But keep in mind this outer boundary is pretty nebulous, so there is no hard line where the Oort Cloud ends.
All this is to say that it isn’t clear how close the Oort Cloud actually gets to the Alpha Centauri system, which is about 4.3 light-years away. Even if the Oort Cloud does stretch halfway to the other system, scientists aren’t sure whether it has its own Oort Cloud.
Despite searching, astronomers have seen no direct evidence of extrasolar Oort Clouds (and they’ve been looking since 1991). Because these clouds would be so far from their stars and aren’t very dense, spotting them would be exceedingly difficult.