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Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

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Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#201

Post by juped »

db48x wrote: post #92
juped wrote: post #9

Earlier quoted context omitted.

Yes, Pluto is the tenth planet. To discover Planet 9, simply open your ephemerides and look for "Neptune".

Back in the day Mercury, Venus, Earth, Ceres, Pallas, Vesta, Juno, Mars, Jupiter, Saturn, Uranus, and Neptune were the 12 planets. You could kinda consider Pluto to be the 13th planet, but in 1930 when it was discovered there were already over 1000 named asteroids. So Pluto is the 1146th planet.

Pallas and Vesta aren't gravitationally rounded, though. But then again, the Moon is (being much larger than Ceres). (It's just better numbered as planet 3-1.)

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#202

Post by goku12 »

rvz wrote: post #152
Qem wrote: post #87

Earlier quoted context omitted.

With current spaceships you would die of old age long before arrival.

Even before that since the food on the spaceship is finite and once it runs out; you would stave to death before the first year during the journey.

Any such ship is going to grow its own food. They may need to carry some extra matter to compensate for accidentally or inevitably lost biomatter. But otherwise they would be able to recycle the same biomatter repeatedly to create food. The only limiting factor is energy. You'll need to add energy in every cycle. Recycling isn't going to happen for it.

Of course, all of this comes with the caveat that nothing like this may exist yet. Sealed mass ecosystems exist in glass jars, but something on the scale of a ship is going to be an entirely different ballgame.

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#203

Post by K0balt »

colonial wrote: post #165
K0balt wrote: post #127

Earlier quoted context omitted.

Aside from research, it could be used to provoke time dilation, though I’m not sure how much you could get out of a basketball sized black hole.:8

If you're interested in creating time dilation, then a planetary mass black hole unfortunately won't get you any further than, well, a regular planet with the same mass. (Aside: time dilation already occurs on and around Earth. GPS satellites have to account for the fact that time runs ever so slightly slower on the ground.)

So, it’s not the local strength of the gravitational field, but the overall mass that matters? How does that work? I mean, if distance/ intensity doesn’t matter, than distance is irrelevant? That seems extremely counterintuitive.

I thought that since you could get into areas where the field was arbitrarily intense, that it would be able to provoke significant relativistic effects.

I had assumed that the small mass would make tidal forces more problematic than with a larger one, but if the distance/intensity of the field isn’t a factor, but only the overall mass… wouldn’t that mean that we could utilize black holes at arbitrarily long distance to provoke those effects, so it would just be a universal constant based on the mass of the universe, and there would be no relativistic effects on a relative basis?

What am I missing here?

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#204

Post by choudharism »

interludead wrote: post #191
K0balt wrote: post #24

I hope this turns out to be wrong. I’m still holding out for a primordial back hole Planet X. That would be soooo cool and unbelievably useful.

Not only would it be insanely cool, it'd give us a once-in-a-lifetime chance to study something that might've formed in the first moments of the universe

I mean, if it's there, we can study it as many times as we want in our lifetime.

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#205

Post by alex_duf »

700 times further => isn't it farther rather than further?

Non native english speaker here, but last I checked further was a metaphorical distance, when farther was a literal distance. You can push a concept further, but you walk farther right? Or did I miss something?

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#206

Post by williamdclt »

alex_duf wrote: post #205

700 times further => isn't it farther rather than further? Non native english speaker here, but last I checked further was a metaphorical distance, when farther was a literal distance. You can push a concept further, but you walk farther right? Or did I miss something?

You’re right in theory, but in practice further is used a lot for literal distance. I don’t think I ever hear farther used at all actually

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#207

Post by dmos62 »

alex_duf wrote: post #205

700 times further => isn't it farther rather than further? Non native english speaker here, but last I checked further was a metaphorical distance, when farther was a literal distance. You can push a concept further, but you walk farther right? Or did I miss something?

If these words have identical etymology (do they?), then the distinction adds no value, in my eyes.

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#208

Post by philistine »

jcranmer wrote: post #144
philistine wrote: post #91

Earlier quoted context omitted.

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.

Yeah that one!

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#209

Post by ben_w »

LeifCarrotson wrote: post #107
AIPedant wrote: post #98

Earlier quoted context omitted.

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.

And Neptune orbits at 30 AU with very low eccentricity, "of course." https://xkcd.com/2501/

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?

Re: Evidence of controversial Planet 9 uncovered in sky surveys taken 23 years apart

#210

Post by smolder »

goku12 wrote: post #198
randomtoast wrote: post #6

I find one theory regarding Planet 9 especially interesting, and that is that it could be a primordial black hole with a Schwarzschild radius on the order of just a few centimeters. So basically, just a golf ball-sized black hole. This would explain why we can see the gravitational effects on the other objects as described in many papers, and it would also explain at the same time why we have no direct observation of…

It would be extremely difficult to observe something that far away from the sun, no matter how voluminous it is. I'm not going to scorn at the idea of a blackhole, but I wonder what process can crush that much mass into such a volume. I don't think it's massive enough to suffer a gravitational collapse.

Primordial black holes can theoretically be much smaller than those formed in the usual way from collapsed stars or neutron star mergers, etc, because the early universe was dense with matter already and perturbations could have caused gravitational collapses for arbitrary volumes. I don't think we've observed any directly, which would be hard as small low-emission masses. They're still a potential piece of the dark matter missing-mass puzzle.
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