Astronomy and Cosmology

Does anyone know? I know that sailors used to use compasses to navigate but does anyone know who actually identified the field surrounding Earth? The person who found out what caused the compasses to actually work in the way they do? Thanks in advance

It's 5am and I've spent all night woundering about the shape of light. I 've decided that it COULD be a disk that when travelling forward gets an indent to it's centre making it a small cone from where the light emminates. this may explain why you cannot see a beam of light from any angle other than from the front, unless it contacts with a medium say a gass or solid object. Any thoughts??

is it just me or does dark matter (and dark energy) seem like a way of fudging a theory in order to make it work? personally the idea of some mystical dark matter keeping our galaxy together is reminiscent of the concentric circles model of the solar system, add to that the fact that the dark matter models keep on becoming more and more complex as new observations remove possible sources of dark matter. I've been starting to think that the entire problem rests on our own incorrect view of gravity, and that some other theory like modified newtonian dynamics is where the real solution lies. This also got me thinking that black holes may also be a relic of an inco…

If I have a spacecraft that has only so much conventional fuel for a conventional rocket and also has an ion engine, could I have it burn the rocket fuel off, and then continue in acceleration with the ion engine? I know that ion engines can accelerate until they run out of fuel or reach near the speed of light, and I don't see any reason why the above scenario couldn't happen... But I wanted to see what everyone else thought. Thanks in advance.

http://www.smh.com.au/news/national/friday-13th-asteroid-a-close-call/2006/07/01/1151174439124.html So on July 3 a 400 meter wide asteroid is to pass within 430,000 km of earth and another is predicted pass within 35,000 km in 2029. There's been a lot of speculation as to what would happen if such an object hit the earth. My question is...what would happen if such an object hit the moon? Given that the moon has a smaller mass and does not have an atmosphere to protect it, would the mass of such an asteroid be sufficient to change the moon's orbit, cause a large loss of mass or severly fracture the surface? Maybe we'd just get a really cool show... Thanks,…

Well, I've been browsing around and ran across Meade's refurbished site. Can anyone give me some advice here? I'm considering the.... TeleStar DS-114AT Meade DS127EC , Polaris DS-2114ATSA Telestar DS-2114ATSA TeleStar DS-2130AT Are these scopes worth considering or should I just save up? I'm not looking to find new galaxies, just the local poop. http://stores.ebay.com/Meade-Factory-Outlet_W0QQcolZ2QQdirZ1QQfsubZ0QQftidZ2QQpZ2QQtZkm Thanks, Rich

Although the motions of galaxies toward or away from us will indeed cause a shift in the light we observe, nothing has so far been demonstrated that directly relates this to the full extent of the shift, and measurements based on this may be erroneous. Our own sun is not moving toward or away from us but it nevertheless produces a redshift of about one part in a million billion. Extremely far away galaxies show a redshift that is smaller for their distance than nearby ones. If the entire redshift were a result of pure motion, then this would mean that the universe is not only expanding, but that this expansion is accelerating, although the mechanism which would cause such…

This is too awesome not to be put here. These instruments were launched before I was born, and one of them is over 6 billion miles from our sun and still has power. Bee http://www.cnn.com/2005/TECH/space/05/25/voyager.space/index.html

Hi guys I've heard that it's possible to listen to the communication going back and forth from NASA Astronauts in space and to their base on earth. If this is true.. please explain where and how this can be done? It's very intriguing.. ~moo

Hi again guys, I have a question that's been bothering me for a while. I can't seem to find a definitive answer - a lot of sites explain about the fact that we are aware light is being twisted and curved on its way through the universe and towards our eyes, but none really explains how we manage to - despite that fact - figure out WHERE exactly the original object really is. I know that the color spectrum of a star visible to us tells us the curvature of its lightwave -- so that we can "uncurve" it.. or, at least this is what I could understand. What happens, however, if something goes through a few curvings? Light curves when it approaches space objects (other st…

Hi: Yes, I realize this is probably just a "news advertisement blurb," but I heard briefly on the news yesterday that a 1/2 mile wide asteroid was coming towards the Earth ("Will it hit Earth? Stay tuned to channel 25 news..."). Anyone heard anything about this? What sort of path is projected? JM

http://hubblesite.org/discoveries/black_holes/home.html this has some similarity to a computer game it involves different kinds of black holes (from stellar mass to galaxy-mass size) you get to scan the sky and observe different stuff from earth with various instruments (see what they look like at radio wavelengths, at Xray, at optical) then you get to travel (at exagerated speeds that you choose) to various destinations that you select the visuals of what you see while traveling, and when you get there are animated. on the whole, from what I saw, they did a good job---fun to play around with and not just one possible experience if you find mistakes in …

I've been reading up on quasars lately. I remember learning, a long time ago, that quasars have been observed to exhibit anomolies or natural law violations. However, I can't find anything in the current literature that suggests this. Am I remembering correctly?

Would it be at all possible to create some sort of hole in the magnetic field around the planet? Maybe using a highly magnetic mesh at some distance, opposite to that at which the field is flowing? Could you create some sort of pocket where UV could get in? Just curious

Guys! One of my pals told me that when we go to space our height will be increased by about 2 inch! Is is so? Is true, plz tell me the reason! Thanks!

Figured I'd make some connections nobody else had. Black Hole Inflation Hypothesis

I don't know of any evidence of a singularity existing in nature. AFAIK singularities exist in physical MODELS and it has happened that by improving the model so it fits the data better, you get rid of the singularity. A singularity is a BROKEN PLACE in somebody's model of nature. Is everybody OK with this? Anybody want to object? Offer an example of a singularity that is known to really exist in nature? I'd be glad to hear of such a thing! OK, what this thread is about is the following: THERE IS NO EVIDENCE OF A SINGULARITY at the beginning of the universe expansion. It would be very peculiar because in the real world we dont see infinities, so why should …

I am planning to make Computer Controlled telescope. Where can I get the step by step information about it? Please, give me the links and information

rather small meteor impact on moon caught in video http://science.nasa.gov/headlines/y2006/13jun_lunarsporadic.htm?list45222 4 tons of TNT brief picture of the fireball looks tiny on the face of the moon

Why don't the constellations change every six months? Surely at one part of the year the stars you would see overhead are in the exact opposite direction to the starts you would see 6 months difference, because those same stars would be in daytime and the night sky is facing the opposite way.

The ChristianAnswers web site attempts to explain how we can see light from stars that are millions of light-years away if the universe was only 10,000 years old. Visit http://www.christiananswers.net/q-aig/aig-c005.html to see their explanation. I don't want this thread to turn into any type of religious debate, so I just want everyone to look at this scientifically and tell me if it's possible. Can the speed of light or time change? It seems to me that this theory would cause some type of conflict between light and time. How can you change one and have the other one remain constant?

I've heard that they are entropic, but it doesn't seem that way, have scientists twisted the idea of entropy so it seems to apply here. Here's how I understand entropy: Light from the sun hits a surface on earth, gets reradiated at room temperature. Visable light is degraded into less useful, less powerful infrared. Now to our black hole: After a septillion years, background radition is radio waves, that get sucked into a black hole, which explodes into gamma rays. How is entropy preserved?

This may sound stupid but if a perpetual energy machine is imposable(due to the laws of thermodynamics) does that not mean that the universe will eventually run out of energy?

this survey covers what has been observed so far and what people think causes them http://arxiv.org/abs/astro-ph/0605208 Gamma-Ray Bursts P. Meszaros To appear in Rep. Prog. Phys., 74 pages, 11 figures "Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma ray burst and its afterglow is reviewed." …

If anyone has a subscription they might want to check this and see what it says. i dont know if the article is any good. http://www.newscientistspace.com/article/mg19025541.800.html there is what looks like some new development here including a Moffat paper just this past week the impressive thing is the first paper here is NOT ABOUT PIONEER BUT ABOUT GALAXY ROTATION CURVES, Moffat started by inventing a modification of Gen Rel that would GET RID OF DARK MATTER as something needed to hold galaxys from flying apart from the observed spin. He made gravity a little stronger way out where it is usually very weak (like out at the edges) and then it fit the observed …