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34 minutes ago, kerbiloid said:
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Indeed faster, though this is angular velocity (2pi/T), while 1014 is "linear" frequency (1/T), so iirc 2 pi should decrease the difference a little.
But that doesn't matter.

Yeah, this was the error I realized. :-P

But yet, my numbers in Hertz are terribly distant from yours. I'm trying to figure out why...

FOUND THE REASON. I'm a dumb SAS, and did the err TWO TIMES. :D 

I'm fixing the fix.

Edited by Lisias
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1 hour ago, kerbiloid said:

@Lisias, maybe rotation period would be taken sidereal (27.3 d), as 29 is synodic one.

That too. But I forgot to add the Angular Momentum to the equation. :) We have an mathematical agreement now.

I have slightly more precise numbers and explicitly did the work that you simplified due really knowing what you were doing. But that's all. :D 

As a Mathematician, I'm a good Programmer as it appears. :P 

Edited by Lisias
Eternal typos from the Englishless mind...
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5 hours ago, Cheif Operations Director said:

scientifically assuming we are not sucked into the black hole the suns light would be sucked into it causing world wide famine and eventual death

You could have tried reading a bit of the thread to see specifically why none of this would take place. Would have taken you what, ten minutes, perhaps? This is not a particularly high threshold for effort to put in before jumping in with your own assertions, especially ones so plainly based on nothing but bad science fiction.

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2 hours ago, K^2 said:

You could have tried reading a bit of the thread to see specifically why none of this would take place. Would have taken you what, ten minutes, perhaps? This is not a particularly high threshold for effort to put in before jumping in with your own assertions, especially ones so plainly based on nothing but bad science fiction.

If the black holes escape velocity is greater than that of the speed of the light particle then how is what I'm saying wrong.

Also I was only joking around with my first post I did not even want to be here!

Make the World take a joke again!

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8 hours ago, Cheif Operations Director said:

It's a joke.

scientifically assuming we are not sucked into the black hole the suns light would be sucked into it causing world wide famine and eventual death

 

4 minutes ago, Cheif Operations Director said:

If the black holes escape velocity is greater than that of the speed of the light particle then how is what I'm saying wrong.

Only a tiny part of the light emitted from the sun goes towards the black hole. That light gets sucked in, sure, but any other light which goes in other directions, say towards Earth, would continue on unaffected. Earth would also not be pulled towards the black hole any more than it is pulled towards the regular, large Moon because its mass is no greater.

Edited by cubinator
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Just now, cubinator said:

 

Only a tiny part of the light emitted from the sun goes towards the black hole. That light gets sucked in, sure, but any other light which goes in other directions, say towards Earth, would continue on unaffected.

Not really. Any the amount energy hitting earth would be minimal. Assuming the earth was not being "sucked" in, and if the moon was on the dark side of the earth nothing would hit that dark side and nothing would hit the sides of the earth from the suns rays. The light bay even just go over earth like the wind on a wing. In the end though earth would receive much less light

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2 minutes ago, Cheif Operations Director said:

Not really. Any the amount energy hitting earth would be minimal. Assuming the earth was not being "sucked" in, and if the moon was on the dark side of the earth nothing would hit that dark side and nothing would hit the sides of the earth from the suns rays. The light bay even just go over earth like the wind on a wing. In the end though earth would receive much less light

I'm not sure I follow you. This black hole's size is comparable to a fine sand grain. It takes up thousands of times less space in the sky than one of Neil Armstrong's footprints, and any photon that doesn't travel directly into it will continue out into space. 

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Just now, cubinator said:

I'm not sure I follow you. This black hole's size is comparable to a fine sand grain. It takes up thousands of times less space in the sky than one of Neil Armstrong's footprints, and any photon that doesn't travel directly into it will continue out into space. 

I see I thought it was a bigger black hole the size of the moon

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1 minute ago, Cheif Operations Director said:

I see I thought it was a bigger black hole the size of the moon

That would be far more catastrophic. The Sun would have to orbit it to stay around...

Edited by cubinator
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2 hours ago, Cheif Operations Director said:

I see I thought it was a bigger black hole the size of the moon

Ok, I'll bite. Again. :) 

The minimal mass for a back hole the size of the moon can be derived from the Schwarzschild radius formula:

rs = (2*G*M)/(c**2)

So, from my previous calculations:

Python 3.6.6 (default, Jun 28 2018, 05:53:46)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> G = 6.67408 * 10**-11
>>> c = 299792458
>>> rs = 1738.1 * 1000
>>> M = (rs*(c**2))/(2*G)
>>> print ("Minimal Mass:" + str(M))
Minimal Mass:1.1702934158434292e+33

So, our Moon Sized Black Hole should have at least ~1.17 × 1033 Kg of mass.

For comparison, Earth has 5.972 × 1024 kg, and the Sun has 1.989 × 1030 kg

2 hours ago, cubinator said:

That would be far more catastrophic. The Sun would have to orbit it to stay around...

Catastrophic is an understatement. That thing would be heavier than everything else in this Solar System. Together. (The Sun accounts for 99.86% of the total mass of the Solar System)

Edited by Lisias
yeah. more typos.
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Just now, Lisias said:

Ok, I'll bite. Again. :) 

The minimal mass for a back hole the size of the moon can be derived from the Schwarzschild radius formula:

rs = (2*G*M)/(c**2)

So, from my previous calculations:

Python 3.6.6 (default, Jun 28 2018, 05:53:46)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> G = 6.67408 * 10**-11
>>> c = 299792458
>>> rs = 1738.1 * 1000
>>> M = (rs*(c**2))/(2*G)
>>> print ("Minimal Mass:" + str(M))
Minimal Mass:1.1702934158434292e+33

So, our Moon Sized Black Hole should have at least ~1.17 × 1033 Kg of mass.

For comparison, Earth has 5.972 × 1024 kg, and the Sun has 1.989 × 1030 kg

Catastrophic is a understatement. That thing would be heavier than everything else in this Solar System. Together. (The Sun accounts for 99.86% of the total mass of the Solar System)

So it would its escape velocity is greater or less than that of light

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2 minutes ago, Cheif Operations Director said:

So it would its escape velocity is greater or less than that of light

It would depend of how close you are from the thing.

At the Event Horizon, when the escape velocity would be greater than c and, so, impossible, everything will be sucked by the sucker.

Above the Event Horizon, things work as we know - you will need a giganourmous amount of dV , but is theoretically possible.

Keep in mind that Earth's mass is so puny compared to this, that we can use a over-simplified orbital mechanics where the Escape Velocity is constant for a body. When we are dealing with such an incomprehensible amount of mass and velocity (c), we have no choice but to use Relativistic Mechanics, and near a Black Hole, every inch affects dramatically the Escape Velocity.

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  • 8 months later...

Learnt something new today.

Space is not limited by speed of light. Only matter and energy are.

How gravity would be affected by this?

https://www.forbes.com/sites/startswithabang/2019/04/20/ask-ethan-how-can-a-black-holes-singularity-spin/amp/

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On 7/2/2018 at 9:04 PM, cubinator said:

Good, then we're on the same page. It might be helpful to enumerate those in the OP.

Well, since the thread got bumped, and likely to bring in some more comments, I've updated the OP as requested. 

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Why it would create a bunch of worm holes, that we can use without being crushed into a singularity, that lead to a bunch of Earth like planets we can move to so we don't have to worry about global warming so we can just relocate 7 billion people and their pets and exploit the new planets until their moons collapse and we can move on again...queue the movie in 5...4...3...

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  • 1 year later...

Got to thinking about this on my drive home this morning..... Would there be any lensing around what would basically be the point source of the black hole?     Would there be a nice and slow "windows screen saver" lens slowly traveling across the sky every night?   And day too... but you can't see background stars during the day.......... although......  there would have to be some lensing going on.... what effect on "eclipses" (more like transits now) would there be???  

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44 minutes ago, Gargamel said:

Got to thinking about this on my drive home this morning..... Would there be any lensing around what would basically be the point source of the black hole?     Would there be a nice and slow "windows screen saver" lens slowly traveling across the sky every night?   And day too... but you can't see background stars during the day.......... although......  there would have to be some lensing going on.... what effect on "eclipses" (more like transits now) would there be???  

This is a surprisingly tricky question, actually. The best way I know to handle it would be to take into account the hypothetical gravitational lensing effects of the sun. The sun's radius is 232,000 times its Schwarzschild radius, and we have been able to make weak gravitational lensing observations during solar eclipses.

So I'm going to make the baseline assumption that visible gravitational lensing is negligible at the edge of a disc 232,000 times the Schwarzschild radius of an object. Since the Schwarzschild radius of the moon is 0.1 mm, that means the "lensing disc" of the moon would be about 23 meters, which is of course far too small to see any distortion with the naked eye.

Then again, one of the proposals for a space telescope would be to place a satellite at 542 AU, where gravitationally-lensed rays converge. Applying the same linear approach to the lunar black hole, the ideal place to put a space telescope would be about 2,681 km away. The effect diminishes with distance. The lunar-black-hole gravitational lensing visible from the surface of the earth would be comparable to viewing the sun from about 1.2 light-years away, which I believe would be too far for any meaningful lensing effects.

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9 hours ago, Gargamel said:

Got to thinking about this on my drive home this morning..... Would there be any lensing around what would basically be the point source of the black hole?     Would there be a nice and slow "windows screen saver" lens slowly traveling across the sky every night?   And day too... but you can't see background stars during the day.......... although......  there would have to be some lensing going on.... what effect on "eclipses" (more like transits now) would there be???  

8 hours ago, sevenperforce said:

Schwarzschild radius of the moon is 0.1 mm

Yeah, that thing's going to be basically invisible. And before you ask about Hawking radiation, take a look at my sig. Moon's about 30 times heavier, so the light emitted is going to be infrared and power output is going to be in nanowatts. The only way you'd be able to tell that the Moon...hole(?) is still there is by its gravitational effects on tides, near-Earth asteroids, etc.

 

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Apologies if this is already covered somewhere in the preceding 5 pages... But:

If instead of the moon being a black hole - or rather the black hole being a moon (in orbit), what would happen to the earth if a lunar mass black hole were falling in in toward the sun, traveling at 32,000 mph and on a direct collision course with the planet?

 

Is the earth solid enough to collapse into the BH - or would it bore a pinprick hole through the diameter? 

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It will rip clean through, but it won't be a tiny hole. The radius in which such a black hole is going to be shredding matter is going to be a lot larger than its Schwarzschild radius. Some of that matter will end up falling into the black hole, releasing enormous amounts of radiation. Most will just pick up a lot of velocity via gravity boost fly-by slamming into matter that was far enough to remain otherwise intact. The net effect will be not unlike shooting a watermelon, where the hole is a lot bigger than the bullet. I don't think that there will be enough energy transfer to stop the black hole or destroy the planet, but it won't be pretty. Huge chunks will be blown out and surface will end up getting liquified at a minimum.

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On 7/4/2018 at 7:44 AM, GoSlash27 said:

HMV,

 No, at least not in our solar system. There's only a couple targets that have a gate orbit anywhere near the moon, and you don't need to get close to the lunar surface to hit it. Farther targets are more efficiently reached by a LEO burn and simple slingshot.

What is HMV?

Quote

K^2,

 Again, that's not how it works. You don't actually pick up "extra" DV, even if you do your burn scraping an event horizon. The depth of the gravity well itself doesn't help or hurt you, it merely determines how far you can bend your trajectory at a high inbound velocity.
 This is the illusion of the Oberth effect; you get the idea that you get a DV payoff by burning at higher velocity. You don't. The payoff comes from making the transfer more eccentric. The energy of an orbit is equivalent to the area it contains. A long skinny orbit contains less area, but reaches the same Ap. Therefore requires less energy to achieve. *That's* how the Oberth effect actually works.

Best,
-Slashy

https://en.wikipedia.org/wiki/Hyperbolic_trajectory

I know tis is an old post that somehow got necro'd, but a change in velocity at Pe has a big effect in the change in velocity at a given distance from a body, and of course, a big effect in the change of the hyperbolic excess velocity when the trajectory becomes hyperbolic.

"

Velocity

Under standard assumptions the orbital speed (v\,) of a body traveling along a hyperbolic trajectory can be computed from the vis-viva equation as:

v=\sqrt{\mu\left({2\over{r}}-{1\over{a}}\right)}

where:

Under standard assumptions, at any position in the orbit the following relation holds for orbital velocity (v\,), local escape velocity ({v_{{esc}}}\,) and hyperbolic excess velocity (v_\infty\,\!):

v^{2}={v_{{esc}}}^{2}+{v_{\infty }}^{2}

Note that this means that a relatively small extra delta-v above that needed to accelerate to the escape speed results in a relatively large speed at infinity. For example, at a place where escape speed is 11.2 km/s, the addition of 0.4 km/s yields a hyperbolic excess speed of 3.02 km/s.

{\sqrt  {11.6^{2}-11.2^{2}}}=3.02

This is an example of the Oberth effect. The converse is also true - a body does not need to be slowed by much compared to its hyperbolic excess speed (e.g. by atmospheric drag near periapsis) for velocity to fall below escape velocity and so for the body to be captured."

Ignoring tidal effects, being able to reach a black hole of lunar mass in lunar orbit means that for the dV required to reach the moon plus an arbitrarily small amount of dV, you can get anywhere in the solar system, with an arbitrarily high speed (arbitrarily close to c).

Of course, tidal forces will prevent you from getting arbitrarily close to the event horizon, and thus from getting arbitrarily close to c before your burn.

Still, if you want a trajectory that gets to Mars in a week, you can get that... don't know how you would plan on stopping, but for a more moderate speed boost, you could have pretty quick outbound journeys with just a few hundred m/s more spent on the capture burn (while you'd be saving a few hundred m/s, at least, since a Mars intercept trajectory takes 480 m/s more than a lunar intercept trajectory)

We could send a probe to Sedna real easy, and get it there real fast...

Edited by KerikBalm
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