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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

#251

Post by d0mine »

AIPedant wrote: post #98
NikkiA wrote: post #70

Earlier quoted context omitted.

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.

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.

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...

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

#252

Post by Ylpertnodi »

tcmart14 wrote: post #156
jiggawatts wrote: post #102

Earlier quoted context omitted.

A black hole reachable in a human lifetime with ordinary chemical rockets would be an amazing laboratory for extreme physics.

What's the first thing we throw in?

>What's the first thing...

Naah, boring. Who's the first person we throw in?

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

#253

Post by bobmcnamara »

colechristensen wrote: post #154
bobmcnamara wrote: post #139

Earlier quoted context omitted.

Hawking radiation does not require an accretion disk. Edit: with an accretion disk, I'd assume we'd have noticed it by now. Outside of that, as a black hole gets smaller, the hawking radiation wavelength should go down. It is rather weak overall, but it would be rather close. I haven't actually done the math, and, this is not my area of expertise. Would a relatively close by small black hole's hawking radiation be br…

The hawking radiation of a 9x earth mass is somewhere in the neighborhood of 0.01 K where the cosmic background is 2.7 K. It would appear to be a very tiny very cold ball. The break even point for hawking radiation vs the cosmic background is about the mass of the moon. I'm not going to do much more searching or calculation but I would be willing to bet a black hole small enough to emit xrays would have a remaining l…

So if a big one emits IR, and a small one emits x-rays is there a certain mass range that would have visible light as its peak emission?

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

#254

Post by juped »

db48x wrote: post #229
juped wrote: post #201

Earlier quoted context omitted.

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.)

That wasn’t a requirement in 1930.

It is required by me, now!

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

#255

Post by munksbeer »

nandomrumber wrote: post #143
zamadatix wrote: post #126

Earlier quoted context omitted.

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.

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.

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

#256

Post by StopDisinfo910 »

halgir wrote: post #225
StopDisinfo910 wrote: post #220

Earlier quoted context omitted.

> And we know that Pluto is the furthest away planet (sue me) I don't need to sue you. It's just entirely incorrect by any sane definitions of a planet. It's not the further if you include similar bodies or not a planet. As I have no interest in saving American misplaced pride (because let's not kid ourself it's about anything else), I don't see the point of spreading misinformation. > Because more people know about…

I know it's not a planet, hence my sarcastic "sue me". I suppose the self-irony didn't work too well over text. My point was that many people still know about Pluto as a body that's at the edge of many people's everyday conceptualizations of the solar system, and I argue that makes it a more useful tool for helping people intuitively understand the particular distances involved. > Only if you were born before it was…

> I don't understand how this ties into American pride (nor am I American), what did I miss?

Pluto was the only planet discovered by an American and most of the people who are extremely attached to it tend to feel that removing Pluto as a planet is somehow taking something away from the USA.

As far as I know, the topic barely exists at all in other countries.

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

#257

Post by halgir »

StopDisinfo910 wrote: post #256
halgir wrote: post #225

Earlier quoted context omitted.

I know it's not a planet, hence my sarcastic "sue me". I suppose the self-irony didn't work too well over text. My point was that many people still know about Pluto as a body that's at the edge of many people's everyday conceptualizations of the solar system, and I argue that makes it a more useful tool for helping people intuitively understand the particular distances involved. > Only if you were born before it was…

> I don't understand how this ties into American pride (nor am I American), what did I miss? Pluto was the only planet discovered by an American and most of the people who are extremely attached to it tend to feel that removing Pluto as a planet is somehow taking something away from the USA. As far as I know, the topic barely exists at all in other countries.

Thanks for explaining, I've never heard about this. In my social circle, nobody would seriously try to argue that it should still count as a "real" planet, but we still refer to Pluto-as-planet in an affectionate, nostalgic way.

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

#258

Post by nandomrumber »

munksbeer wrote: post #255
nandomrumber wrote: post #143

Earlier quoted context omitted.

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.

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.

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.

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

#259

Post by jeffhuys »

ednite wrote: post #82
ednite wrote: post #20

Earlier quoted context omitted.

Honestly, if there is a golf ball–sized black hole out there chilling in the outer solar system, I'm all in. Let’s fire up a replica of TARS, load up ChatGPT inside (TARS-GPT, patent pending), and yeet it straight toward the Schwarzschild golf ball. It’ll narrate live. Imagine the livestream: “Approaching event horizon. Spaghettification at 3%. Mood: stretchy.” “Entering gravitational lensing zone… wow, even my token…

Not sure why the downvotes—if I came off wrong, my apologies. I genuinely meant it in a humoristic way. I'd honestly love to see a probe launched into a black hole.

It’s because you either type like an LLM or because you use an LLM. We don’t like that. At least, I don’t.

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

#260

Post by manwe150 »

Dylan16807 wrote: post #169
manwe150 wrote: post #150

Earlier quoted context omitted.

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…

Your first nitpick only makes sense with a weird definition of "approaches" for the context, so I think it just adds confusion. They're pretty clearly talking about something that is headed in the direction of the sun and not already in orbit . And the comment you're responding to already mentioned that other bodies can make a capture happen. Nobody was saying capture is impossible.

I thought the context is orbital mechanics, for which the term approach is the common term for a portion of the trajectory where the bodies move towards each other. Take any Wikipedia article for an orbiting solar body and search approach eg: https://en.m.wikipedia.org/wiki/Halley%27s_Comet
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