Astronomy and Cosmology

What is the difference between astronomy and cosmology?

So,to start off my disbeliever of your faith. An observation into space is a look into the past.A far distant quasar or whatever object, is but an observing of an event that happened a very long time ago,relative to speed of light or whichever electromagnetic wavelength you observe an event.From that point of view you ablilty to see a structure out of this universe would have the requirement of a selection of a time period to trace to a time all objects that construct this universe.Oh say 2 galaxies,one 400 million light years away another 600 million.To construct a universe correctly you would obviously need to place that 400 million light ago galaxy where it was 600 mi…

most of the galaxies that we will ever be able to see with our telescopes are receding from us at FTL speeds and indeed were recedingfrom us FTL when they emitted the light that we are now receiving from them and Einstein's theory of special relativity does not contradict this because it has nothing to say about recession speeds (the rates at which distances are increasing) but only about speeds of local encounter but some people dont realize this and assume that the galaxies we are looking at cannot be receding from us FTL and they may also think the redshift is a doppler effect which you learn already in basic introductory astronomy courses it is not…

I'm investigating the mechanics behind rotating space stations for a science fiction piece that I'm writing, and I'm curious as to how some parts of it work and hope that maye someone here has links or an explanation of certain parts, or even just advice (like: stop writing fiction and get a real life, you nerd). I'm going to continue looking up on it after I've posted this anyway. I know a lot of people won't be interested by this or consider it irrelevant, but if people here learn something then surely that's a positive use for the forum? Nobody has to respond anyway; I'm getting ideas just from writing this. But the actual problems I have are vague and I'm really just …

I was wondering, how large are the event horizons of black holes? Not any sort of miniature black holes, but ones likely to form from the collapse of very massive stars. Also, is there any easy way to calculate it?

I was wondering, does anyone here know what would happen to a satellite if it were placed at the Earth-moon barycenter, between the two but nearer to the moon, where the gravity of the Eatrh and moon cancel each other out? I'm wondering as I've heard of proposals to build space telescopes and such there, but I could never work out how the satellite would stay there without going out of orbit. As far as I know, the pull of gravity from both the Earth and moon would cancel out and the telescope would carry on in a straight line, but the Earth-moon system would continue to rotate. As soon as the moon was nearer, the telescope would start to be attracted by the moon and then …

http://www.space.com/scienceastronomy/galaxy_filaments_040607.html By Robert Roy Britt New observations of the center of our Milky Way Galaxy have revealed the origin of radio-emitting filaments that puzzled astronomers for two decades. The filaments range from 10 to 100 light-years in length and 1 to 3 light-years across. They occur only in a very narrow area, within about 900 light-years of the galactic center, a region crowded with old and new stars. A light-year is the distance light travels in a year, about 6 trillion miles (10 trillion kilometers). The Milky Way in its entirety spans more than 100,000 light-years. The filaments emerge from pocket…

i know this may seem like a simple question, but i would like to know: if things boil at low temperatures in space due to the low pressure how do comets form? wouldn't the water boil, rather than freeze? wat about the ice around saturn? if i were to shoot water out of a spaceship would it freeze or boil? thanks

Do you think Mercury's surface is made of gold? Like the closer you are to the sun, the heavier the elements?

this is a landmark paper that represents several firsts essentially they programmed the emergence of the universe in a computer simulation and ran it over and over again to get averages the preprint was posted at arXiv in April (arXiv is where you read things first before they have been published in the journals) here's the link: http://arxiv.org/hep-th/0404156 ----- I guess there are several observations to be made about this. Gravity is the geometry of spacetime so a theory of gravity should generate the geometry. You should not have to pick a fixed geometry ahead of time (as is done in string theory---it's the main shortcoming in fact) instead, the…

The linear relationship in hubbles law implies that the universe is uniformly expanding. Knowing this, can astronomers/physicists study the motions of other galaxys and come up with a center point from which everything started? In essence, the center of the universe? Wouldn't this also give us an idea of the approximate age of the universe?

Is Our Universe Too Perfect to be Random? August 14, 2002 08:30 CDT from cosmiverse It's a question as big as the Cosmos itself: could the prevailing theoretical view of the universe be flawed? In order for the cosmos -- as we currently understand it -- to exist, it would have required outside help. In other words, it would have required a miracle to create our view of the universe, or outside intervention from "God". If the universe is ever-more-rapidly expanding as we believe it to be, then it is destined to eventually repeat itself. According to a recent report in the journal Nature, that's the view of Leonard Susskind and his team from Stanford University,…

If an asteroide or any spherical object is found after the pluto, can sun be able to hold this object ?Is gravitational force of the sun extend up to pluto only?

Hi I was just wondering why we always keep looking for water as a sign of life. Couldnt there be any chance that there could be life without water or oxygen or anything else we labled as necassary for life? I just find it that it kinda limits our view of the universe. I just keep wondering if somewhere out there, there is an intelegint life form that relies on lets say iron for survival. Just a thought. P.S. Sorry about spelling. :banana: hehe banana hehe

Now, this is another one of my crazy schemes, but I figured I have to ask. I saw a show not too long ago on how we plan to colonize Mars. They said that we'd have to thicken and heat the atmosphere. One of the main plans for how was to extract carbon from the soil and release it into the atmosphere, then, once it warmed enough, begin the process of bringing plants. If this carbon plan is true, then can't we make it twice as fast? I was searching before and I came across this site. It says: So, why can't we put machines on Mars that heat up the CO2 enough to seperate the carbon from the oxygen, and do two things at once? Not only do we heat the atmospher…

Niel Cornish is an Australian who has a monkey for a pet http://www.physics.montana.edu/faculty/cornish/ and he studied at Cambridge with StephenHawking and at Princeton and is now in the physics department at Montana State U. and he and co-authors have a paper in Phys Rev. Lett. 21 May 2004 saying that whereas cosmologists generally allow the U might be infinite because it looks spatially flat nevertheless there is enough uncertainty about the curvature that it might be just slightly positive in which case the U would be finite but very very large Cornish et al have determined that it could be no smaller than 78 billion LY (halfway round as I unders…

what is dark energy why does it have negative pressure how does negative pressure accelerate the universe's expansion does anyone want to offer some explanations? I will try to give some partial answers for a start, which can be elaborated or disagreed with The key to the whole discussion of dark energy is the Friedmann equation (a simplified version of the basic Einstein equation of GR gotten from the Einstein equation by assuming a kind of uniformity to the universe that makes things easier to calculate) [math]\frac{a''}{a}= -\frac{4\pi G}{3}(\rho + 3p)[/math] a is the scale factor, so expansion corresponds to a' positive and acceleration corre…

I write this post in regard to the essay in support of Intelligent Design having the title, "Was There Ever Nothing?" and found at http://everystudent.com/journeys/nothing.html The essay is nonsense. In particular,

MOND or modified newtonian dynamics serves as an alternative to dark matter. I think that most of you guys here at scienceforums believe in dark matter, but it has much evidence to support it. here are some web pages http://members.rogers.com/mercy/ http://www.worldhistory.com/wiki/m/modified-Newtonian-dynamics.htm http://www.astro.umd.edu/~ssm/mond/mondvsDM.html EDIT: poll should say which theories explain better the inconsistencies of newtonian physics?

Consider that the maximum separation for keeping the binary planet bound can't be more than Dmax = (1/3) R { ( Ma + Mb ) / Ms }^(1/3) In words: The components (both of them habitable planets) must have a maximum separation not greater than one third of the cube root of the ratio of the sum of the planets' masses to the mass of the star, multiplied by the distance between the star and the barycenter of the binary planet. Consider that R must be always within the liquid water temperature region around the star. Consider that, to a good approximation when 0.8 < (M/Msun) < 2.5 the luminosity of a star may be found from its mass by the relation: …

Well my America girlfriend (she comes from Cleveland) reackons that she can see the big dipper from our night sky (in New Zealand) as well as a couple of other constallations, i was just wondering if this is true or not? because the northern hemisphere is looking at the night sky in a different angle to the southern hemisphere although there will be a region of overlap. So is this the same constallations seen in the northern hemisphere?

If there was no time before the big bang occur, how did it start? Could the enormus energy of matter broke trough time, hmm... this doesnt sound to logical to me?!

i'm in a process of making one myself and though someone else might want the info. the most expensive thing you'll require are the mirrors, but everything else is pretty cheap. http://members.aol.com/sfsidewalk/dobplans.htm

What do you think, what's the maximum size of solid planet. Earth is yet the greatest known solid body in the universe. In what situation and around what kind of star would a giant solid planet be born.

They had a couple of really good shows on, but to my disappointment i only saw portions of them. One was the Elegant Universe. It had some really cool computer graphics. The other was about String Theory, wow was that some weird stuff. If you dont know about these check out NJN's website for tv schedule, they will probably be re-airing them.