A question about outer space properties

[NoStateofMind]

I was watching the science channel about our universe and how it works (ignorant of most things in space.). They made mention about an astronaut who experimented with salt inside a bag to see what would happen. He discovered that salt clumped up instead of repelling each other. I suspect they were implying a low level gravitational pull. They went on to mention that when planets were developed it was this clumping that took place until the matter compacted into the rock we live on. Could have missed something but I don't think I'm too far from the theory. However when you think about the asteroid belt and then try to apply the above you have to question why they haven't become some sort of planet by now. Anyone have an explanation of why not?

Also how in the hell do we know what the Milky Way galaxy looks like?

 

[T_Yamamoto]

The title was misleading. Thought op was going to be able buildings in space.

 

[NoStateofMind]

The title was misleading. Thought op was going to be able buildings in space.

I've got a nice moon dust front property for sale if you're looking

 

[Crono]

- Constant speed relative to one another in orbit (like race cars keeping distance around a track)
- We are on the edge of a spiral arm. We have a good view of our galaxy (basically we can observe around). Images of our galaxy aren't photographs, just renderings or composite.

 

[NoStateofMind]

- Constant speed relative to one another in orbit (like race cars keeping distance around a track)
- We are on the edge of a spiral arm

So centrifugal force is the reason why the asteroid belt isn't a planet? Essentially?

Even if we are on the edge it still seems quite a stretch to paint the whole picture right? I mean me standing on the beach in Florida with a telescope doesn't show me the whole earth. Am I correct in my analogy?

EDIT: I see you edited. Hmm

 

[IronWing]

I'm not familiar with the salt experiment but I am certain that gravitational attraction between salt grains is not what caused them to clump. The masses are simply too small to act over the time frame of a space trip.

 

[SsupernovaE]

Tidal stress from Jupiter's gravity.

 

[Crono]

So centrifugal force is the reason why the asteroid belt isn't a planet? Essentially?

Even if we are on the edge it still seems quite a stretch to paint the whole picture right? I mean me standing on the beach in Florida with a telescope doesn't show me the whole earth. Am I correct in my analogy?

It's not force, just velocity and distance. If they were moving slowly close together and at different speeds, they would eventually ball up together. Gravity is weak at distance, though. Other objects passing through the asteroid belts (like comets)would probably impact and lose/gain debris with those asteroids. Orbits (stable) generally keep asteroids, planets, moons, etc. from colliding unless they are in decaying orbit.

Your analogy isn't perfect because on earth we are on a single spherical object. It would be more like being on the edge of a crowd of people and drawing a picture of what's around you while people slowly move in the crowd. You can paint a fairly accurate picture of the crowd, even if you are technically part of it.

EDIT: I'm not an expert or even close, so I'm sure someone will l tell me I'm completely wrong and my analogy stupid.

 

[Mr. Pedantic]

So centrifugal force is the reason why the asteroid belt isn't a planet? Essentially?

Not really. In the early Solar System it was thought that the gravitational force from Jupiter's presence prevented the formation of a single body. Since orbits were quite unstable at the time, there would be periods where the orbits of the planets would criss-cross, and Jupiter would dip into the asteroid belt and disturb the orbits a bit. This was only while the bits of rock were liquid, after they cooled whether Jupiter was there or not doesn't matter anymore.

Even if we are on the edge it still seems quite a stretch to paint the whole picture right? I mean me standing on the beach in Florida with a telescope doesn't show me the whole earth. Am I correct in my analogy?

EDIT: I see you edited. Hmm

We can see Andromeda quite well, we can see the core, and we can see the speeds at which stars move in the galaxy as well as their densities in certain volumes in space. That should get us to the idea that we are in a spiral galaxy to start with.

There's actually quite a lot of controversy over the exact structure of the Milky Way.

 

[Fritzo]

Tidal stress from Jupiter's gravity.

This is correct. Jupiter's gravity it enormous. If it weren't there, the asteroids most likely would have clumped together by now.

BTW- It is believed that this clumping phenomenon also explains the formation of dust bunnies under your bed (not kidding).

 

[SaDiZTiKStyLeZ]

It's bad to divide by zero.

 

[Pulsar]

OP, can you quote where you read the salt stuck together?

Pure salt will, but most table salt has anti-caking agents that prevent it from sticking. I was unable to google what you were talking about.

Quick someone LMGTFY

 

[Northern Lawn]

Yep. Same with the rings around Saturn, gravity keeps them mostly in orbit and dispersed.

 

[The Boston Dangler]

http://en.wikipedia.org/wiki/File:ESO-VLT-Laser-phot-33a-07.jpg

this is our view of what the ancient greeks called the milky way - where the "gala" in galaxy comes from

here is the salt experiment:
http://videos.howstuffworks.com/discovery/40910-how-the-universe-works-the-power-of-dust-video.htm

 

[Northern Lawn]

http://en.wikipedia.org/wiki/File:ESO-VLT-Laser-phot-33a-07.jpg

this is our view of what the ancient greeks called the milky way - where the "gala" in galaxy comes from

here is the salt experiment:
http://videos.howstuffworks.com/discovery/40910-how-the-universe-works-the-power-of-dust-video.htm

Did they rule out static electricity?

 

[Braznor]

Here is a riddle few can answer, but everyone can ask.

Why does the gravitational field of an object attracts all other objects of varying mass at the same rate? A feather does not accelerate downward any slower than a rock on Earth in vacuum conditions.

 

[randomrogue]

Also how in the hell do we know what the Milky Way galaxy looks like?

Are you asking how we know it's a spiral or if we've ever seen it? Go out on a dark night, especially during the winter, away from light pollution and you can see the Milky Way. You can also see the Andromeda Galaxy with the naked eye if you know where to look. The Milky Way and Andromeda are the same kind of Galaxy except that Andromeda is bigger (although possibly not more massive).

 

[Triumph]

Here is a riddle few can answer, but everyone can ask.

Why does the gravitational field of an object attracts all other objects of varying mass at the same rate? A feather does not accelerate downward any slower than a rock on Earth in vacuum conditions.

Because F=ma. Newton's law of gravitation says that the attractive gravitational force between two objects is related directly to the product of their masses and inversely related to the square of the distance. Drop two different masses from the same height, the attractive force between each of them and the earth is different. But that doesn't tell you their acceleration, for that you need F=ma. When you solve for their acceleration in F=ma, you take into account the larger mass again. What happens when F goes up on the left side of the equation, but m also goes up proportionally on the right side? "a" has to remain the same. In purely mathematical terms,

m1 = mass of the feather, or the rock

F=G(m1)(m2)/r^2 = (m1)*a

Solving for "a", you can see that m1 (the mass of the feather, or the rock) drops from both sides of the equation, so the acceleration due to gravity depends only on the weight of the earth and the distance from the center.

a= G(m2)/r^2

 

[DrPizza]

Here is a riddle few can answer, but everyone can ask.

Why does the gravitational field of an object attracts all other objects of varying mass at the same rate? A feather does not accelerate downward any slower than a rock on Earth in vacuum conditions.

I *hope* that anyone who has taken a high school physics class can answer that question. Refer to Newton.

 

[silverpig]

Did they rule out static electricity?

Sounds like a consequence of random motion, inelastic collisions, and van der waals forces.

 

[IronWing]

Sounds like a consequence of random motion, inelastic collisions, and van der waals forces.

Yeah, the leap the narrator makes from clumping in small particles in close proximity to gravitation between asteroids is unwarranted and I don't think that was what the astronaut was getting at. I think the astronaut was trying to explain the very early stages of aggregation, why the smallest dust particles get together.

 

[rbV5]

outer space properties

what?