Astronomy and Cosmology

I posted this in another thread without response, so I'll try again: What is the current explanation for why random particles within a nebula would in fact be drawn together towards an empty spot in space to eventually form a planet? What is the "motivation" so to speak for random particles to form together at some arbitrary point?

I want to know whether or not the universe has a center of mass. Is there any experimental fact that dictates that the universe must have one? Thank you

The universe is expanding in all directions. It is not the galaxies that moves away from each other, but space itself who is expanding. Space is created between the galaxies. What was a million light years long is a million and one light year long. (You can use Hubble constant to know how long it takes) Here on earth we don't feel this expansion and we have no clue that this expansion is happening in our galaxy. Why ? Is it possible that is because the earth and all other masses in the milkyway "eat up" that space created by the expansion ? Let suppose that's the case: The universe is expanding and all masses eat up that space. The bigger the mass the more it ca…

The March '05 issue of Scientific American has an interesting article about misconceptions regarding the Big Bang and the expanding universe. The full article is now available on their web site at: http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=0009F0CA-C523-1213-852383414B7F0147 Here are some of the more interesting bits: Question: What kind of explosion was the Big Bang? Wrong Answer: The Big Bang was like a bomb going off at a certain location in previously empty space. Right Answer: It was an explosion in space itself. The space we inhabit is itself expanding. There was no center to the explosion; it happened everywhere. T…

Most scientists agree that if any aliens visit us, they would be more advanced than us. The scientists also say that they aliens would probably not be hostile. However, humans have a long history of being hostile to civilizations that are less advanced than them. When Europeans first started going to Africa, they found African tribes with less technology. As a result, the Europeans took the Africans, and made them slaves. When Europeans first started going to America, they began killing the Native Americans. Then they took their land, and made them live on little reservations. As you can see, humans have had a long history of being hostile to civilizations…

How do we know that Galaxies aren't smaller and therefore require less "dark matter" to hold them together? What factors are taken into account? Distance (redshift) angle subtended (is that the correct term) How much stronger (percentage wise) would gravity have to be to not require dark matter?

The question is pretty much self explanatory. Total energy=? Total mass=? Temperature=? Volume=? Density = ? Also, while I'm on the subject, what is the escape velocity of the universe, way back in time when all the matter was concentrated near the center of the universe? Thank you

The fundamental construction of the universe is bi-seasons' whole including state-varying organization,state-forming organization and control ogranization.The earth,the Solar System,galaxies,clusters of the galaxies,organisms and societies are bi-seasons' whole. Big Bang of the universe is nonsense. from Zero Space-Time Theory:Grand Unified Cosmologgy email:yjzh273@tom.com

Most of us know Saturn is the 6th planet from the sun & that is encircled by a broadband of rings. Astronomers in the 1600's were mystified now they have been studied by telescopes & space probes. In 2004,the Cassini space probe arrived at Saturn to study the giant gas planet it's rings & moons. It carried a mini-probe,called Huygens,to investigste Saturns moon..."Titan" Scientists believe Titans atmosphere was similar to the air here that existed billions of years ago.....has this been proven? & are we any closer to learning the make-up of Saturns rings? have we learnt anthing from these investigations?...Has this been a wasted enterprise or are we ben…

http://www.marsdaily.com/news/marsexpress-05d.html Courtesy from Quantum's "Space-Daily"....us.2u

In 1974 the Arecibo radio telescope transmitted a coded message towards the M13 star-cluster. M13 contains 300,000 stars & lies near the edge of our Galaxy, 21,000 light years away. The message consisted of 1,679 bits of info. If intelligent beings recieve the code,they should be able to re-arrange it into 73 lines of 23 bits. In this form it shows a series of shapes, including the "Arecibo-Dish", our solar system. & a human, if life forms do work it out, a return message would take about 48,000- years to get here from M13. .....To me that seems such a pointless excercise! ...us.2u

http://www.spaceflightnow.com/news/n0502/19grb/

I came across this bit of information the other day...I thought I'd share it. Did you know the word "Milky Way" is named after the Greek word "galactose" - a milk sugar, and sharing the root as the word "galaxy."

http://www.space.com/businesstechnology/technology/rocketplane_050224.html http://www.rocketplane.com/spaceplane/spaceplane.html Finally somebody has the right idea. A single stage spacecraft that is completely reusable. And since it is designed around an already exisiting jet it should be pretty cheap to build.

Well, apparently NASA found one, with pictures from the orbiting Mars Express. The theory goes that a catastrophic event released a great deal of liquid water at some point, which flooded the basins and formed pack ice. Later, dust drifted down and covered the pack ice, preventing sublimation. I think this is rather interesting, personally. I mean, if the first step towards life were prions, viruses, and viroids, what about endospores of primitive microorganisms in this frozen sea? Possible, certainly. There's a link below with the full article. http://news.bbc.co.uk/1/hi/sci/tech/4285119.stm

Here comes my assumption: Imagine, there is an additional gravity force which increases proportional to the distance: F = c m M r c: constant m: small mass (star) M: big mass (galaxy) r: distance between m and center of M equal of centripetal and centrifugal force: c m M r = m r w^2 w: angular speed division by m and r : c M = w^2 This is what can be observed: the angular speed inside a galaxy is just a function of its mass. Maybe this force is nothing else than the bending of the space by the time. e.g. gravity also bends the space. IMHO this formula is not more fantastic than worm holes, dark enery and matter, multiple univer…

OK--I understand that due to the Earth's rotation, that someone standing on the equator is moving 1000 MPH West to East. And I even understand that the Earth is going around the Sun, so we are moving at a speed that could be discribed as "just a hellin'." Now I got this kid who want's to know how fast the solar system is moving in the galaxy. Can any of you smart fellers help me on this? And while you are at it, you might as well figure out how fast the Galaxy is moving through space, because that is prolly what he's gonna want to know next. By the way, how many directions are we moving in at the same time? Any why doesn't that make us dizzy?

hello. i'm new to this site and i have a very passionate interest in cosmology. however there is one thing that i cannot get my head around. The universe is defined as all time, space and matter. everything. If the universe is expanding, then what is it expanding in to, because technically it would be the universe anyway...

Hope this brings Hubble up to date http://hubblesite.org/

Does anyone know the most accurate measure of the circumference of the earth in miles? I have found: 24,902 miles. How accurate is that?

After watching a sort of documentry in my geology class I was wondering 2 things about gravity: 1. how do we measure gravity? 2. how do we detect gravity and changes in gravity? any feedback on this would be nice, since no matter how well my teacher tries to explain it...he still cant explain it. thanks

(Sorry if I posted this in the wrong section) What is the longest day on Earth? I know it's different depending on where you live but my friend was telling me that tomorrow as in 22nd February (I'm from Australia by the way) is the longest day because the moon's gravitational pull is slowing the Earth's spin at the moment. Is this true? I always thought that the longest days were when the Summer Solstice occurs (Approx. 22nd December in Southern Hemisphere and approx. 21st June in Northern Hemisphere) Confuzed plz help

http://spaceflightnow.com/news/n0502/19grb/ What a story

Sean Carroll tries to explain it all in an hour talk. He is a wellknown cosmologist at U Chicago who happens to have attractive slides and a popular style. http://pancake.uchicago.edu/~carroll/universelab05/universelab.pdf it is 3 MB so it takes a little while (maybe 3 minutes?) to download

Fishing for a theoretical spell check, that is, I've got a theory that I think is neat and I'd like it kicked around a bit. At least I "think" it's original, havn't seen it elsewhere, but if you have - be a pal and link me. Specifically I was thinking that there was the potential for false perception accounting for both missing mass and apparent acceleration of universe expansion situations, based on the assumption of certain stable states that we have no true evidence for, specifically volume/mass. My primary thought here is that the volume/mass of any part of the universe need not be a constant to be true to our observations so long as the volume/mass is co…