if all the planets aligned....

[Dough1397]

would it?

 

[Fricardo]

All of the planets have aligned (although it's pretty rare) and no, gravity pwned nothing. The gravitational effects of the planets on each other and the sun are tiny compared to the gravity well created by the sun itself. Everything continues as normal.

 

[plastick]

*HAW HAW HAW!!!*

"...would gravity pwn us..."

LMAO

 

[DrPizza]

The pull on Earth from the other planets does cause some variation in our orbit around the sun... hence the orbit is considered a chaotic one (although very closely approximating an ellipse) However, consider this: rather than have them *all* line up with the earth, the net effect would be greatest if Mars and beyond all lined up with the earth, then the other 2 were on the opposite side of the sun... (well, I suppose they'd still be lined up....) It still wouldn't effect us much though. Also, if you know the orbital periods of the planets, they'll all be lined up approximately once per the lowest common denominator of their periods.

 

[DCypher]

Technically yes, noticably no.

The reason is that a gravitational field corresponds to an inverse square law. Meaning every unit you move away, your effective gravitational pull is equal to F=1/r^2.

Actually, if a black hole was placed where are sun is now, it would not suck us or the solar system in at all, because the inverse square law makes the event horizon much less than expected.

 

[DrPizza]

Originally posted by: DCypher
Technically yes, noticably no.

The reason is that a gravitational field corresponds to an inverse square law. Meaning every unit you move away, your effective gravitational pull is equal to F=1/r^2.

Actually, if a black hole was placed where are sun is now, it would not suck us or the solar system in at all, because the inverse square law makes the event horizon much less than expected.

wouldn't that depend on the mass of the black hole?

 

[DCypher]

Sorry, forgot to include that in that case the mass of the black hole would be the mass of our sun.

Thanks for the correction bro.

 

[Calin]

The gravitational influence of the Sun (which contains like 90% or more of the mass of the solar system) is inferior to the gravitational effect of the moon (less than half). This is the reason why tides differ between full/new moon and quarter moons. Why high tides and low tides differ in a smaller degree? Simply because the Sun's influence (gravitational influence) is smaller than the moon's

Calin

 

[SagaLore]

I think they all ligned up in 2000. At most, didn't it cause a problem with our magnetosphere?

 

[SagaLore]

Originally posted by: DCypher
Sorry, forgot to include that in that case the mass of the black hole would be the mass of our sun.

Thanks for the correction bro.

However that would be impossible, because if it were the mass of our sun then it wouldn't be a black hole. I know you're just making a point though.

 

[DCypher]

Yes, thats right, or else it would be a hella small black hole.

 

[cquark]

Originally posted by: DCypher
Yes, thats right, or else it would be a hella small black hole.

Actually, not that small. Any post-fusion star with more than 1.4 solar masses will collapse into a black hole. Of course, stars shed a great deal of their mass during their giant phase and during supernovae, so stars generally have to be much larger than 1.4 solar masses during their main sequence phase to eventually become a black hole.

 

[DCypher]

ah, thats right, good call. Your bringing back my memory.

 

[DrPizza]

Originally posted by: Calin
The gravitational influence of the Sun (which contains like 90% or more of the mass of the solar system) is inferior to the gravitational effect of the moon (less than half). This is the reason why tides differ between full/new moon and quarter moons. Why high tides and low tides differ in a smaller degree? Simply because the Sun's influence (gravitational influence) is smaller than the moon's

Calin

IIRC, isn't the sun's effect on the tides about 30% of the amount of effect the moon has? Definitely smaller, but not insignificant. I know I looked it up once before... if I search I might find it.

 

[Calin]

I thought something like that, about a quarter of the moon's effect. And this is from a mass that is over 90% of the entire solar system, closer to the Earth than every other signifiant mass except Venus, Mars and Mercury.

 

[DrPizza]

Originally posted by: SagaLore

Originally posted by: DCypher
Sorry, forgot to include that in that case the mass of the black hole would be the mass of our sun.

Thanks for the correction bro.

However that would be impossible, because if it were the mass of our sun then it wouldn't be a black hole. I know you're just making a point though.

Hmmm... If it were the mass of our sun, it wouldn't collapse into a black hole... but does that necessarily mean that there couldn't, at least for a brief amount of time, be a black hole with that mass?

 

[Jeff7]

Originally posted by: Calin
I thought something like that, about a quarter of the moon's effect. And this is from a mass that is over 90% of the entire solar system, closer to the Earth than every other signifiant mass except Venus, Mars and Mercury.

More specifically, the Sun contains over 99% of the mass in the solar system.

 

[SagaLore]

Originally posted by: DrPizza

Originally posted by: SagaLore

Originally posted by: DCypher
Sorry, forgot to include that in that case the mass of the black hole would be the mass of our sun.

Thanks for the correction bro.

However that would be impossible, because if it were the mass of our sun then it wouldn't be a black hole. I know you're just making a point though.

Hmmm... If it were the mass of our sun, it wouldn't collapse into a black hole... but does that necessarily mean that there couldn't, at least for a brief amount of time, be a black hole with that mass?

I don't think so. The only reason it's a "black hole", is because the gravity is so great that light cannot escape it. Mass is responsible for gravity. There could never be a black hole with the mass of our sun.

 

[cquark]

Originally posted by: SagaLore

Originally posted by: DrPizza

Originally posted by: SagaLore

Originally posted by: DCypher
Sorry, forgot to include that in that case the mass of the black hole would be the mass of our sun.

Thanks for the correction bro.

However that would be impossible, because if it were the mass of our sun then it wouldn't be a black hole. I know you're just making a point though.

Hmmm... If it were the mass of our sun, it wouldn't collapse into a black hole... but does that necessarily mean that there couldn't, at least for a brief amount of time, be a black hole with that mass?

I don't think so. The only reason it's a "black hole", is because the gravity is so great that light cannot escape it. Mass is responsible for gravity. There could never be a black hole with the mass of our sun.

It's possible to have black holes of *any* mass.

Gravitational attraction is not dependent solely on mass; it also depends on distance. After all, large stars don't start as black holes, right? Whether an object becomes a black hole or not depends on its density, not simply its mass. If you could compress the Sun to increase its density so that light could not escape it, then you would have a solar mass black hole.

We do not know of any physical process that would make a small black hole, outside of the Big Bang, but we are looking at the possibility of producing nano-black holes in new particle accelerators.

 

[JonB]

Now I'm curious. I checked, and Jupiter has 0.1% of the Sun's mass. (the Sun is 1000 times more massive). In another thread a few weeks back, someone discussed the Barycenter of the Sun/Jupiter combination and that the mass of Jupiter was large enough that the barycenter of the Sun was actually outside of its own heliosphere. I'm afraid I can't quite agree with that now, seeing the difference in mass. Does anyone know better?

see - "What would happen if the moon disappeared" - http://forums.anandtech.com/me...id=50&threadid=1477884

 

[JediJeb]

As to the OP original question, the planets did align in May 2000 and nothing happened.

As to the solar mass black hole, not sure what the limiting mass for formation is, but if one formed with that mass it would only have and event horizon of inches or maybe feet, but not very large at all.

 

[pakigang]

A little out of topic

I read somewhere that the gravitational forces of the planets also generate some specific types of hormones in us i.e. like the moon has tidal effects, it also affects us. Anyone has some detail info on this or this is just a theory? I read in some astronomy book.

 

[gsellis]

There was some disaster nut who wrote a book called "The Jupiter Effect" a decades ago. We were all supposed to die in all of the floods and earthquakes or some such drivel. Never read it, just remember the laughter. That was supposed to happen in 1982? Dogpile/Google is your friend now that you have a search key.

 

[Rebel Nugget]

Originally posted by: Calin
The gravitational influence of the Sun (which contains like 90% or more of the mass of the solar system) is inferior to the gravitational effect of the moon (less than half). This is the reason why tides differ between full/new moon and quarter moons. Why high tides and low tides differ in a smaller degree? Simply because the Sun's influence (gravitational influence) is smaller than the moon's

Actually, the sun's gravitational influence is incredibly greater then that of the moon. If what you said is true, then we would orbit around the moon instead of the sun. That is obviously not the case. However, there is a germ of truth in what you said about tides.

The reason that the moon is the primary influence on tides is not because it has a greater gravitational effect then the sun on the earth but because since it is closer to the earth the change in relative position between different sides of the earth. I'm not very good at clearly explaining things, but here I go. On the side of the earth that the moon is closest to there is a signicantly greater attraction the on the opposite side of the earth (gravitational force is inversely proportional to the distance between the two objects squared). In terms of numbers, the moon is 384,400 km away. The diamtereof the earth is about 12,600 km. What this means is that there is that on the side furthest from the moon, there is a difference in gravitational attraction (compared to the other side) of about 5%. That makes it so there is a resulting tidal bulge in the oceans.

The sun doest not have that effect because the distance between the sun and earth is so great already that the gravitational effects on each side of the earth are nearly equal. So even though the sun has more of a gravitational effect on the earth then the moon, the moon has more of an effect on the tides because it is closer and there is a greater disparaity of gravitational force on each side of the earth.

Like I said, I'm not so hot at explaining stuff... so if this is a pretty ambiguous explanation, let me know and I can try to find a webpage that does a better job of explaining.

Edit: Oh yeah, in addressing the original post question. I think that something around 5 of the planets aligned a few years ago, back in 1990's and there were a bunch of cults and dooms-dayers freaking out about it. But even if all the planets aligned there would be only like a .01% change in gravitational force on the Earth.

 

[kindest]

screw gravity what if some way some how the earths orbit changed signficantly enough that everyone on earth had vertigo.

how scary would that be.