Newbie Questions

[sammyooba]

What makes less dense things orbit denser things continuualy?

 

Like if you get a bowling ball and a pingpong ball. You settle the bowling ball in the middle of the bed. Then you lightly toss the pingpongball and it'll orbit the bowling ball for awhile then itll get sucked in because it runs out of forward energy.

 

What makes it so earth continuualy orbits earth and not get sucked into the Sun?

 

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And how do dust clouds form in space. The one that makes galaxies.

 

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[swansont]

Things orbit around the center of mass of the system; the COM will tend to be close to or within a more massive object, depending on the relative numbers. Density, by itself, isn't the relevant quantity. The earth is almost 4 times denser than the sun.

 

Orbits continue because the forward momentum is enough to keep them in perpetual freefall.

[Janus]

What makes less dense things orbit denser things continuualy?

 

Like if you get a bowling ball and a pingpong ball. You settle the bowling ball in the middle of the bed. Then you lightly toss the pingpongball and it'll orbit the bowling ball for awhile then itll get sucked in because it runs out of forward energy.

 

What makes it so earth continuualy orbits earth and not get sucked into the Sun?

 

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The ping pong ball runs out of energy because it loses it to the friction between it and the bed. The Earth orbits in the vaccuum of space where friction doesn't come into play.

 

If your bed sheets were made of a fricitionless material and you sucked all the air out of the room to remove air friction, the ping pong ball would also continually orbit the the bowling ball.

[Klaynos]

The ping pong ball runs out of energy because it loses it to the friction between it and the bed. The Earth orbits in the vaccuum of space where friction doesn't come into play.

 

There is friction because it's really not a very good vacuum. But it is very very very small compared to a ping pong ball on a bead...

[sammyooba]

thanx for the replies, i understand orbit now.

 

Still have 2 questions:

 

1) what makes the cloud of dust (The one that makes galaxies).

 

and

 

2) the gravity become weaker as you are farther from the source. Like is Pluto less affected by the sun? And can anyone direct a link to the experiment that was done to prove this?

[iNow]

1) what makes the cloud of dust (The one that makes galaxies).

The dust particles each, being a source of mass, pull things toward them gravitationally. As dust particles get closer and closer, they start to lump together (or, aggregate). This aggregate then has a higher mass than any of those dust particles alone, so the "lump's" gravity gets increasingly stronger, hence attracting more dust particles, hence increasing it's strength of gravity again, hence attracting more dust particles... and sooner or later, many of these "lumps" become galaxies.

 

2) the gravity become weaker as you are farther from the source. Like is Pluto less affected by the sun? And can anyone direct a link to the experiment that was done to prove this?

 

Yes, Pluto is effected by the Sun's gravity (that's why it orbits around it). However, the strength of the Sun's gravity is much less at Pluto than on Earth (or, in fact, anywhere closer than Pluto is to the sun... like Neptune, Jupiter, Mars, Venus, etc.). As the distance increases from the strong gravitational source, the strength of gravity drops by 1 over that distance squared. ... [math]\frac{1}{d^2}[/math] ... where d = distance.

 

It's called the inverse square law.

 

http://www.discoveryofpluto.com/newton.html

[Newton] went so far as to calculate the strength of this force at the distance of the Moon. In doing so, he determined that gravity falls off as one over the square of the distance to the center of the Earth.

This relationship is known as the inverse-square law of gravity, and is expressed

 

Force = G m1m2 /d2.

 

Here, m1 and m2 are the masses of the two objects, and d is the distance between them. G is called the gravitational constant.

 

 

Here is a link with a mathematical visual and some formulaic demostrations:

 

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html#isqg

 

 

The link below has a much more approachable explanation of the same:

 

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/circles/u6l3b.html

[sammyooba]

The dust particles each, being a source of mass, pull things toward them gravitationally. As dust particles get closer and closer, they start to lump together (or, aggregate). This aggregate then has a higher mass than any of those dust particles alone, so the "lump's" gravity gets increasingly stronger, hence attracting more dust particles, hence increasing it's strength of gravity again, hence attracting more dust particles... and sooner or later, many of these "lumps" become galaxies.

 

 

 

Yes, Pluto is effected by the Sun's gravity (that's why it orbits around it). However, the strength of the Sun's gravity is much less at Pluto than on Earth (or, in fact, anywhere closer than Pluto is to the sun... like Neptune, Jupiter, Mars, Venus, etc.). As the distance increases from the strong gravitational source, the strength of gravity drops by 1 over that distance squared. ... [math]\frac{1}{d^2}[/math] ... where d = distance.

 

It's called the inverse square law.

 

http://www.discoveryofpluto.com/newton.html

 

 

 

Here is a link with a mathematical visual and some formulaic demostrations:

 

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html#isqg

 

 

The link below has a much more approachable explanation of the same:

 

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/circles/u6l3b.html

 

 

wow, thanx truely, will be a big help.

 

About the cloud of dust, what makes it?

[iNow]

About the cloud of dust, what makes it?

Again, the individual particles of dust, when they get close to one another, pull on each other with their gravity. As I understand it, anything with mass exerts a gravitational pull. So, the individual dust particles begin to aggregate (come together), and form larger lumps. These larger lumps are just a big collection of dust particles which have come together.

 

Then, as the lumps get larger, it has more mass, so it exerts a stronger gravitational force on the things around it. Through lots and lots of years, this process continues, and the lumps get bigger with every dust particle that "hooks up." Also, other lumps will then pass by each other, and they too will be attracted gravitationally and join together.

 

That's about as detailed as I've got though. I've only read this type of informatoin for personal enrichment, and have never actually been formally educated in the topic.

 

 

This page may be of use to you (there are actually more than one, so if you become interested, be sure to click "Next" and keep reading).

 

http://amazing-space.stsci.edu/resources/qa/galaxies.php.p=Astronomy+basics%40%2Ceds%2Castronomy-basics.php&a=%2Ceds

[sammyooba]

ok, I get some parts of it, except where all that dust comes from.

 

3 more q's

 

these are all incorrect right?

 

1. the centers of gravity of Earth and Moon are fixed (do not move) with respect to the corresponding planetary/lunar surfaces

2. the speed of light is constant (it doesn't change with time)

3. Light beam between Earth and Moon travels through media that do not change with time

 

and in correlation with those 3 q's, are these true?:

 

1. Neither Earth, nor the Moon are rigid bodies. Their interiors are partly liquid and semi-solid. Hence, observations of our scientists can be explained by slight changes in mass distribution inside Earth/Moon interiors. Incidently, some notorius and unexplained errors in satellite positions can be expained this way too.

2. Recently, our scientists noticed that the speed of light seems to decline slightly. When light becomes slower, it takes more time for it to reach the Moon and come back. Whoever assumes that the speed of light is constant is bound to conclude that the distance between Earth and the Moon increases.

3. The moon seems to develop its atmosphere. If you look at a new moon, you will be able to see its entire outline. In the past, this was not possible. Observing the entire lunar outline is only possible if the moon has an atmosphere. As you know, light travels through atmosphere slower than through vaccum. Hence, thickening of the lunar atmosphere would contribute to a conclusion that the Moon drifts away from Earth. Increase in pollution/composition of Earth's atmosphere (CO2) has a similar effect.

 

thanks

[swansont]

2. Recently, our scientists noticed that the speed of light seems to decline slightly. When light becomes slower, it takes more time for it to reach the Moon and come back. Whoever assumes that the speed of light is constant is bound to conclude that the distance between Earth and the Moon increases.

 

To whom do these scientists belong ("our scientists")? And to what studies do they refer? i.e. where did you get that quote?

 

That and explanation #3 would seem to imply that the recession of the moon is thought to be an illusion.

 

The single Google hit I get is http://www.thiaoouba.com/faq.htm

Crap, crap and more crap.

[sammyooba]

My q's were from that site, I was wondering that if any info. in that site is plausible.

 

The books on that site was an interesting read so I thought that if some info. on that site was realistic, so could the other.

 

There is 1 interesting thing, it claims that this book was written around 1980s, and said 'electrons store information', and the site claims that this was discovered in 2000. Anybody know if this is true?

 

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I'm guessing Australian scientists, I did a quick search on 'light slowing', and I got http://www.rense.com/general28/erin.htm

 

First paragraph "A team of Australian scientists has proposed that the speed of light may not be a constant, a revolutionary idea that could unseat one of the most cherished laws of modern physics -- Einstein's theory of relativity."

[swansont]

My q's were from that site, I was wondering that if any info. in that site is plausible.

 

The books on that site was an interesting read so I thought that if some info. on that site was realistic, so could the other.

 

There is 1 interesting thing, it claims that this book was written around 1980s, and said 'electrons store information', and the site claims that this was discovered in 2000. Anybody know if this is true?

 

So much on that site is wrong, it would be a chore to sift through and find the stuff that's right.

 

I'm guessing Australian scientists, I did a quick search on 'light slowing', and I got http://www.rense.com/general28/erin.htm

 

First paragraph "A team of Australian scientists has proposed that the speed of light may not be a constant, a revolutionary idea that could unseat one of the most cherished laws of modern physics -- Einstein's theory of relativity."

 

 

That was from 2002. If there was anything to support that proposal, they would have announced it.

[Jacques]

3. The moon seems to develop its atmosphere. If you look at a new moon, you will be able to see its entire outline.

Completely false. The moon as no atmosphere. At new moon, you can se the entire moon because the earth reflect some light from the sun into the dark part of the moon. And it is not a new thing. It's been observed since man started to observe the sky. http://en.wikipedia.org/wiki/Planetshine#Earthshine