Astronomy and Cosmology

Here's my video from China! Got very lucky with weather when I hear what happen to others who made the journey!!!!

Hi. one of the main goals nowdays is accelerating space shuttles in speed so we could travel even while exploring the vast milky way galaxy one thing is not clear to me, and thats why do we have to be limited with the shuttles speed at all? let me explain: since there is no friction in space, and since our shuttles have their own engines to accelerate - how come , speed isnt accumulating to greater values? take a normal shuttle that is packed with alot of fuel turn the engines on, lift off, after a while it leaves the earth atmosphire, and from this phase every ounce of fuel burnt accelerates the frictionless shuttle more and more as she gains speed.. with su…

is there any proof? actually gravitational force is attractive so it should be shrinking by the way if it had to. pls explain where i was wrong.

Heres my theory about the moon. Keep in mind it's just a theory and maybe a stupid one. Ok the moon is kind of like a shield to Earth because of all the asteroids hit the moion all the time. Now if the moon wasn't there we would be would be getting hit with all the asteroids and maybe some we cant take and there would be millions of deaths. I know it may be stupid, but I was pondering it the other day. This is probably a stupid one, who knows? Well if the moon was a part of the Earth before, then why does it have a core like the Earth? If it's just a chunk of rock that detached then went into Earths orbit then why does it have an atmosphere? What I think is that when …

See the story below. I heard on the radio it was moving between 50 to 100 Kilometers per second. They said crashing into gas clouds created a greater explosion than if it hit a solid surface. http://news.cnet.com/8301-19514_3-10291824-239.html

I'm writing an article on the 1859 event of a direct hit on Planet Earth of a solar flare, triggering aurora all across the North Hemisphere, observed as far south as Cuba (!) and Rome (!!) http://science.nasa.gov/headlines/y2008/06may_carringtonflare.htm So I'm reading through the archive of the American Science Journal for 1859-1860, which contain the direct observations from countless astronomers and observatories across the August 28th - Sept 2nd period when the Aurora were at their maximum. http://diva.library.cmu.edu/ajs/browse.jsp?n1=6 And something jumps out at me from all the various reports - the predominance of the colour red in the prominence a…

Has any entity theorised about what Earth would be like now IF the moon had never become detached ? I know the moon is essential for how life originated & survived on earth but would the added gravitational field of Earth changed much on its own

http://news.bbc.co.uk/1/hi/uk/8113627.stm

i mean like we have dozens of rockets tested each year, but nobody is really interested in going to the moon or to mars, right? so if we can get some rockets into space then in space where there's no air resistance, an extra gallon of fuel should create the inertia needed to send a rocket like 50 galaxies away, see if there's anything interesting there...

btw i was just on google.com and their "google" logo is embedded in some lunar terrain. apparently today is 40th anniversary of lunar landing... btw this is highly off topic but i never did get it: how come like jupiter and saturn and stuff (which has very large gravity and is very cold) a "gas giant" with ammonia and hydrocarbons or whatever... shouldn't the gases condense, be liquid or solid under all that gravity?

I was reading an article about the properties of light and it was stated that light does not react directly to a gravitational field but instead reacts to the space-time curvature associated with the field. Since light from distant galaxies (or even close ones) does not travel in a straight line from the source to our observations and instead travels through the expanding space of a hypersphere in a curve varying with the distance from us, is this not a de facto curvature of space and could it have implications for speed and wavelength (specifically the red- shift) variations ?

hi, it seems as though I have read claims that we can see a galaxy or star form, but how deceptive is it to say that when it takes tens of millions of years at the very least for an event like this to happen, yes? so, how would we have any idea what we are actually looking at, that is to say if we have never seen a star being born how do we know we are looking at one of the stages in the birth of a star when the amount of time we have to view the process wouldn't even be equivalent to watching one still frame of a movie. they say we have seen a star being formed as if it's like watching a video of the event, but as I just explained we are basically watching a stil…

Has anyone used the Sky Server (SDSS) for conducting astronomy experiments? I really like the facility, but I have a question of anybody who has used it. The data dictionary they publish is nice, but it is shy on details regarding the definition of each data element. For example, the sample 20 SQL queries provided to new users are straightforward in structure, but in terms of how the fields are used, more in-depth knowledge seems to be required. Has anyone else figured out where to get more detailed scientific background info? Thanks!

On Earth, Methane is primarily produced by Biological processes*. So strong is that link, that Methane in Mars' atmosphere strongly suggests the presence of sub-surface Methanogen micro-organisms: Methane is a product of Biology. For Methane to be in Mars' atmosphere, there has to be a replenishable source... The most obvious source of Methane is organisms. So if you find Methane in an atmosphere, you can suspect there is Life**.And, Methane is commonly observed across the Cosmos. * Martin Ince. [Rough Guides] Earth, pp. 256-257. ** http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/4243321/Mars-methane-discovery-hints-at-presence-of-life.html;…

Hello everybody, I have been watching the history channel's show "The Universe" . In one of the seasons "Most Dangerous places on the universe" they say our galaxy is moving towards our neighboring galaxy Andromeda and they will collide after some billion years. But in another season "Dark matter and Dark energy" they say that the universe is expanding due to the presence of some dark energy and the galaxies are continuing to move apart. I find both these information conflicting each other. How can galaxies collide, if they are moving apart?. Any ideas ?

I was thinking about the asteroid "Apophis" recently thats scheduled to be a NEO in 2036 and was wondering if it was actually going to hit us how could we prevent it? I've heard a lot of mention that we might use nuclear devices to divert the course of a rock bound for earth, then it hit me. Space is a vacuum. How on earth would a nuclear explosion transmit it's energy into the asteroid efficiently enough to divert it? My only guess is we would have to land the device directly on the service. I know there are other methods of diversion but I guess the real question is are what are the effects of nuclear weapons in the vacuum of space? An EM Pulse is going to be th…

I know that this is enevitably an obvious question, however I myself have no competence in physics, and thus curiosity has compelled me to ask: Why is it that despite a relatively uniform distribution of gravitational force, due to the sun's (somewhat) spherical shape, planets' orbits are elliptical, and not spherical? Or, in simpler terms (as I seem to have inadvertently confused myself): Why do planets have elliptical orbits? Any thoughts? (or answers:D; those are even better!)

i'm confused about how COBE (the Cosmic Background Explorer) measured the frequency peak of the Cosmic Microwave Background (CMB). the following seems clear to me and relatively straightforward: for black body radiation, i.e., for an ideal photon gas in local thermodynamic equilibrium with matter, e.g., the surface of last scattering of the CMB, the spectral radiance, I_nu (T) = [2h/c^2][nu^3/(exp(h nu/[k T])-1)] or I'_lamba (T) = [2hc^2][1/lamba^5(exp(h c/[lambda k T])-1)] <forgive my clumsy notation, i don't know how to do LaTeX notation>, peaks at nu_max or lambda_max, respectively, such that c/lambda_max = 1.76*nu_max. although the lambda_max peak is th…

There is a logical way to split the singularity of the BB theory, using basic observations within physics. It only requires a single extrapolation from an old experiment. If you look at photons, these behave as both particles and waves. The double slit experiment helped to demonstrate the wave nature of photons because only a wave could go through both slits at the same time without considerations like binary pairs. Mass particles are also particles and waves but they act more like particles than waves. A rock thrown at a double slit will can only go through one at a time. It wave is rather small in relative energy. All we need to do to expand a mass based sin…

Just wanted to know if anyone had any suggestions for cosmo/phys books that are a little past leymans versions. Something that goes more in depth with the math and beyond just the concepts. Thanks

http://www.astronomy.com/asy/default.aspx?c=a&id=8337 M87 is one of the larger galaxies in the Virgo cluster----the nearest major cluster of galaxies near us. M87 is estimated about three times the mass of Milky. It has been known for a long time to contain a supermassive black hole, but they did not have an accurate estimate of how massive. The black hole at the center of our galaxy is only about 3-4 million solar. So that puts it in perspective. The one in M87 is estimated 6.4 billion solar. Basically they observe the rates that stars are orbiting the center, and estimate the total mass, and the mass of the dark matter halo, in several ways, and then…

Yes I call it the ( M & M ) star system. So we have the big dipper in our sky that points to the Polar Star. So what about the M & M star system ?. The oposite side of the Big Dipper and our polar star are ( Two Large M & M ) star systems. So now we have candy in our sky and I imagine the M & M' s candy stars will come apart to j:doh:ump over the polar star and make it into the Big Dipper dureing the ( Arrora Borealis ) display of lights. John T.

Please ponder the Gravitational Potential Well of a massive central body: [math]U = - \frac{G \; M}{R}[/math] Crucially, Gravitational Potential Energy is negative. Thus, other bodies placed into this Gravity Well will lose Energy -- and, hence, by Einstein's Mass-Energy Equivalence (E = m c2), they should lose Mass, equal to: [math]\Delta M = \frac{U}{c^{2}} = - \frac{G \; M}{c^{2} \; R}[/math] Plugging in appropriate numbers, this yields Fractional Mass Loss effects of order: At Earth's surface -- 10-9 At Earth's orbit -- 10-8 At Sun's surface -- 10-5 At Neutron Star's surface -- 10-2 At Black Hole Event Horizon -- 1 Thus, by these admittedly pri…

Just how do multiple stars from? Alpha Centauri, for instance. Where they three proto-stellar disks that got caught in their gravitational fields and began to orbit; or, did they form in one proto-stellar disk that had enough mass to form two additional stars?

Take a look at Space Weather for impact info. Not much detail for now...