Now I know you have no idea what that means. The radius of WHAT?
Well, over the past year, two NASA probes have been sending data from both approximate ends of the radius of the Solar System. I find this to be totally cool and…oh yeah. I know what you’re thinking: “What the hell are you talking about?”
On new years’ day of 2019, the New Horizons’ probe flew by what was then called Ultima Thule. (the name was changed to ‘Arrokoth” because “Ultima Thule” was too European sounding) We’ve never going to come close to anything that far until we invent warp drive, so it’s literally as far as we’re going to get even if that plucky little robot manages to make it to interstellar space alive. Symbolically, this is the far end of the solar system’s radius.
The other end. Last September, the Parker Solar Probe had its second perihelion, getting as close to the Sun as any spacecraft has ever been. This was one of those major events that nobody noticed.
The reason is obvious, it’s going to be years before it manages to actually “touch the Sun” in 2024, (which could be only a few thousand miles from the actual barycenter of the solar system!!!!) and this means that what happened last month is only the beginning.
But approximately and symbolically, Parker hit the end of the stick. So in the old year, between it and New Horizons, we’ve done the entire radius of the Solar System.
This is totally cool.