[AIPedant]

It makes even less sense for Earth because Earth's orbit is near-circular, whereas Planet 9's hypothesized orbit is highly eccentric, more so than Pluto.

Most people don't know off-hand that Pluto is ~40-50AU from the sun, so 700AU is hard to conceptualize.

[zamadatix]

They're all horrible to conceptualize because people don't commonly deal with how far even something like the Earth to the Sun is, I don't think there is any winning answer here - at least an AU is consistently defined and maybe slightly more likely to be familiar, but it's still just about as crap to be honest.

Side note: Apart from AU already being defined as average distance and not current distance, the distance referenced is how far out the proposed object is now, not its general orbital parameters. At that orbital distance 23 years of motion isn't going to be much change in distance even if it's in a hyperbolic orbit.

[AIPedant]

My point was not about intuiting the distance, it's about what the solar system looks like qualitatively, as a cartoon with orbits drawn around the sun. Most people have no idea if 700AU is closer than Pluto, a little further than Pluto, or much further than Pluto. 15x the distance of Pluto is much more direct.

[zamadatix]

What's the benefit of communicating something is 15x the distance of Pluto if people are expected to have at least a ~15x error in how far away Pluto is supposed to be? At that point it's all nonsense, nothing is relevant anymore. Might as well say something useful for those who do have a clue about the solar system.

Hell, it's been nearly 2 decades since Pluto was itself planet 9. Just bringing the name up in a discussion about planets is going to cause more confusion.

[setr]

15 time further than the furthest once-planet is fairly intuitive to say really freaking far; you don’t need to know how far pluto is, just that it’s the furthest.

[AIPedant]

> Might as well say something useful for those who do have a clue about the solar system.

The source we are discussing is space.com, a website which frequently mentions Star Wars and whose stated mission is to "transport our visitors across the solar system and beyond through accessible, comprehensive coverage of the latest news and discoveries." My comment was about communicating this research in a way that better fits "most readers" of space.com. If you think qualitative orrery models are beneath you and want to exclude those people, then you are not the target audience. Just go read the actual paper.

[nandomrumber]

700 AU is 4 light days.

Or four days travel at the speed of light, to an outside observer. Or instantaneous for anyone travelling at the speed of light.

[lolc]

Thank you. When I want to know astronomical distances, I use the speed of light to get a sense. Moon? One second. Sun? Eight minutes.

Time units are more approachable than distances I will never cross.

[munksbeer]

When you put it this way it depresses me (). It just illustrates just how unimaginably big space is, considering something that might be considered part of our own star's solar system can be four freaking light days away. We'll never get out of our solar system will we?

() Not really, I'm using artistic hyperbole.

[nandomrumber]

The most distant Voyager probe is about 167 AU out, or one light day, and it’s been travelling for 48 years.

If we are going to get anywhere in space it’s looking like we’re going to need some kind of technological leap. Would be wild to see that happen this lifetime.

[d0mine]

To give perspective to 700AU: the nearest star is ~270 kAU i.e. the object is at ~0.26% (close to the Sun)

https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_i...

[dragonwriter]

> Most people don't know off-hand that Pluto is ~40-50AU

~30-50AU if you are referring to the range of orbital distance.

[AIPedant]

No, I was referring to the range of my recollection when I read Wikipedia earlier this morning while writing the parent comment :)

[LeifCarrotson]

And Neptune orbits at 30 AU with very low eccentricity, "of course."

https://xkcd.com/2501/

[ben_w]

I was just thinking of this XKCD comic specifically.

Most people won't even have the slightest idea what 1 AU is. Most people know less about most topics (including space) than the original ChatGPT (3.5) did — probably only people who at least started a degree with a space sciences module are likely to know more than 3.5, and I expect plenty of space.com readers to be enthusiastic amateurs rather than professionals.

That said, I do I expect the average reader of space.com to know what an astronomical unit is, but even so I don't expect them to know the average orbital distance of Pluto.

But is even that assumption my quartz?