I think “15 times further from the Sun than Pluto” is more meaningful for most readers than “700 times further from the Sun than Earth.” If it exists, it’s way way way out there.
I dunno, '700 AU' gelled for me instantly, '15 times the distance to pluto' doesn't even make sense given pluto's orbit isn't anywhere near circular.
New horizons launched 9.5 years before it reached Pluto, and your average reader who has an interest in Planet 9 will likely know it took New Horizons about that long.
15x means no one alive today will see a mission that reaches the planet, and that's more accessible for most readers per above.
I think “15 times further from the Sun than Pluto” is more meaningful for most readers than “700 times further from the Sun than Earth.” If it exists, it’s way way way out there.
I dunno, '700 AU' gelled for me instantly, '15 times the distance to pluto' doesn't even make sense given pluto's orbit isn't anywhere near circular.
The length of 2.1 trillion Olympic swimming pools.
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.
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…
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.
Isn't this exactly how Pluto was discovered? Due to an innacurate estimate of the mass of Neptune (not corrected until Voyager I think), people were hunting for a large planet to explain the discrepancy. After a bunch of searching they happened to find Pluto, but it was not the Planet X they were looking for. The mass estimates for Pluto were gradually downgraded from many Earth masses to 1/500, which is the true rea…
Yeah. If Pluto had been slightly heavier, we’d probably have ended up with a definition of a planet that included its mass instead of clearing its orbit to keep Pluto a planet. But Pluto was cooked when we figured out it’s not really heavier than Ceres.
> But Pluto was cooked when we figured out it’s not really heavier than Ceres.
You mean Eris? Pluto is ~10 times the mass of Ceres.
I think “15 times further from the Sun than Pluto” is more meaningful for most readers than “700 times further from the Sun than Earth.” If it exists, it’s way way way out there.
Most readers probably know Pluto is the... well... it's not the farthest dwarf planet. But they know it's far, but don't realize just how far it is. I certainly didn't until I watched a video about it.
700 further from the Sun than Earth is tangible as "really really far" though.
I think “15 times further from the Sun than Pluto” is more meaningful for most readers than “700 times further from the Sun than Earth.” If it exists, it’s way way way out there.
I think both work. The average reader doesn't need to conceptualize these distances. They just need to know they're reallllly far away and realllllllly realllllllly (9x) far away. You can use the earth or pluto distances as relative scales.
I dunno, '700 AU' gelled for me instantly, '15 times the distance to pluto' doesn't even make sense given pluto's orbit isn't anywhere near circular.
New horizons launched 9.5 years before it reached Pluto, and your average reader who has an interest in Planet 9 will likely know it took New Horizons about that long. 15x means no one alive today will see a mission that reaches the planet, and that's more accessible for most readers per above.
New horizons is hardly the fastest possible probe over the next 30 years.
(9.5 * 15 / 3 = 47.5) + 30 years = 77.7 so some teenagers could live to see a probe reach it even without hypothetical life extension technology.
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.
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 disc…
> 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.
Correct, but my point is you don't need to lose energy to enter orbit. You don't need complex reverse slingshot interactions. You just need a low enough relative velocity to not shoot off the other side. I would expect this to be the norm for capture, not some exotic phenomenon. A ball doesn't need to lose energy to be captured in a valley either. You just apply a radial force to turn a line into a circle. Anything t…
Anything that approaches the sun will do so with faster than escape velocity because the gravitational potential energy gets converted into kinetic during the approach. Newtonian mechanics is time-reversible - just like it's impossible for an object in orbit to spontaneously escape without gaining energy from somewhere first, it's impossible to enter orbit without losing energy to another body.
Small nit: this is for objects approaching from infinity in a two body system. Otherwise the object can be in orbit and already be “captured” there. For example, the moon also approaches earth slightly over the month while speeding up, then slows down while moving away. Or it could just be a 3 body system, which is chaotic and can’t be modeled accurately and can have objects spontaneously eject from the stable system (even though the physics is indeed reversible)