Astronomy and Cosmology

Another hero of mine is Hans Alfven and I just heard on the radio of a report on the solar wind implicating Alfven waves as an acceleration mechanism to get particles up to one or two million miles per hour speed.

I realise that Hydrogen has been around nearly since the very beginning, and the elements up to Iron are all made in stars, and elements Past Iron are Super Nova made. does that include the radioactive Isotopes, or were they made some other way?

This is my first post, so forgive me if this is a stupid question (most of mine are) but I do not understand red giants. A normal star is in equilibrium between radiation pressure pushing out from nuclear reactions in its core, and gravity pulling in. When a normal star, such as our own sun, runs out of fuel, the outward pressure from radiation necessarily stops. Gravity doesn't, of course, so the sucker shrinks. Except it doesn't. It expands into red giant first, flings off lots of stuff, and only then becomes a white dwarf. Dumb star.

Hi. When estimates are made concerning the number of galaxies in the Universe, such as 100 billion, are these estimates of the total number using some sort of calculations (that are beyond me) which take into account expansion rates, density, age, shape, and so on.... or are these estimates only regarding the number of galaxies in the observable Universe? In other words, have scientists essentially ruled out the possibility that the Universe has an infinite number of galaxies at this point in time?

so i was looking online for info into this question and there wasnt really a whole lot. most of the stuff i found was a bit old and more of speculation. i suppose its mostly speculation anyways but i was curious if there was any newer info about them. how would something millions and sometimes a billion times the mass of the sun come into being? My obviouse guess would be that the occasional planet or star would get to close and get pulled in, along with all the gas around and such. but how often is this? i suppose over millions or billions of years it happens. But the biggest black hole im aware of is about 4 billion times the mass of the sun. that means that in…

Hello all, I serendipitously found this science community while searching for info about Jupiter's largest moon, Ganymede. I am a sci-fi writer and I am hoping to learn much from this intellectual community and hopefully offer constructive ideas for your edification, as well. In my current novel, Ganymede has an industrial colony established upon it. I have researched the potential of terra-forming Ganymede and have found complications that will require imaginative solutions - possibly the suspension of some of the laws of physics and thermodynamics. However, in spite of that, as much as I can, I want my speculative fiction to be based on as much sound or innovati…

Is there not the possibility of traveling from one point in three dimensional space to another within a period of time lesser than that which would be required in the three dimensional universe by entering, for example, a four dimensional universe, and ?bypassing? the curve or other indirect 'passage' from a to b as we could two ends of a curved two dimensional surface in 3D space?

Well, first I'll start out by saying that I love cosmology and relativity (ever since I learned about it) - granted I dont have a very good... er cross that out, non existent handle on the mathematics behind it, I like the theories and such. Anyways, my question is that how can we possibly know the shape of the universe? If its so large, how would we be able to tell the difference between a flat and curved system? or a curved and closed system? thanks

(Wasn't sure where this topic would fit). I used to be keenly interested in the prospects of Life on Mars (or anywhere else in our system). I thought that the discovery of life on Mars would be a major indication of what we could plug into the Drake Equation. But things changed when it was realistically proposed that planets could ‘seed’ each other via impact ejecta. Now, as far as Drake and its implications, life on Mars (or anywhere in your Solar system) means nothing. Right?

In a binary system, when one star has a type Ia-II super novae the partner star in that system is still there, so would the black hole and star just continue to orbit? What if the supernovae star surpasses a type II and becomes a supermassive black hole, will the other star gets pulled in, but then what would happen to the black hole, would it just continue sort of spinning by itself, but don't singularity's not spin? Sorry if that's phrased sort of confusingly.

I heard about the setna planet.Explain about it

So I'm taking the trash out to the curb at approximately 0225 PDT (Las Vegas) and I look up at the moon and I see the weirdest flickering object at about the 11 o'clock position (if the moon were a dial on a clock). It's flickering like white and what looks like red and all things considering, looks like it's a pretty goos size object. What the heck is that thing??? -Shawn

This is what I've been wondering. I got some answers from this web page http://www.damninteresting.com/?p=741 But, there are some other things I'm wondering about. It says you won't freeze immediately in space because of the vacuum, but why would you freeze at all? I thought vacuum is basically the ultimate insulator. Heat always moves from something hotter to something colder, but if there's nothing for it to move to, there's nowhere for the heat to go and it would stay hot. I can also see why something could get hotter because it is exposed directly to the sun's rays, but wouldn't that depend on how far away you are from it? Why is it that there are cold things…

Hey. I am new here. Have red wikipdia and other sources from one end to other. Didn't find answere to this. How exactly does light get through any medium. I now about the reflection and refraction all the angles etc. what I care for the most is... weather a photon dies when encounter any phisical body or not. The best answere I got in internet is that when photon encounters any atom it dies and gives extra energy to the atom, so since atom has too much energy it must spred it further (suspiciously) it creates new photon in the same direction and emits a wave in the same frequency as received photon-wave. this has a logical mistake 1. Why does atom…

Just found this article, which could be another stepping stone in bolstering GR. What I particularly liked about this approach, was that professional and amateur astronomers were involved in taking measurements, please see the Physicsworld article below... http://physicsworld.com/cws/article/news/33818;jsessionid=BE7D6AE627411F98A30D168DA0F28777

guys please help im presently in 12 grade n want my carrer in astorphysics..as im in india der are no undergraduate courses offered so to get into this field of science i gotta do my bthec in any field frist n den go for mtech in astrophysics. now for that i have to clear xms afteron sowhich field in bTech. should i take so i'll be helped latter?

In standard cosmology, matter is assumed to be distributed throughout all space more or less uniformly. So if space is infinite volume, the amount of matter is infinite. If space is a boundaryless finite volume then the amount of matter is finite as well. In neither the finite or infinite case is there any edge or boundary to space, and since the region occupied by matter coincides with the whole of space there is no edge or boundary to the occupied volume either. the question of space infinite or finite has not been resolved yet. What is your opinion? Do you think space volume could be infinite?

Is it possible that the Universe is no larger now than it was the instant it came into existance so instead of space expanding it is in fact matter that is shrinking? So an outside observer, presumably a 4D fellow, would see no real difference.

THE ESSENCSE OF A BLACK HOLE Everyone states a black hole is the death of a galaxy or a wormhole to another universe--- BUUUTTT what if it is actually the big bang therory being played out, can we say this is not the way life first started eons ago the central collection of universal matter to be comprosed for the creation of life and new planets again. and yes we do have a Black hole in the center of our galaxy also. so is this galaxy going to reborn anew or totally destroyed?

Hi guys, I'm new to the Forums, and have an interesting question for you. So I was wondering what do you guys think would happen here on earth if the moon had a sudden shift in it's orbit. I have heard some interesting ideas, but just wondering what you think... Shmoo

This idea came to me the other day. From a practical point of view, gravity is more effective at lower temperature. This is not to say that the gravitational force is a function of temperature, just that the same amount of gravity is more affective at lower temperature. For example, if we could switch off the fusion core of the sun, so it cools, gravity can make it smaller. If we switch it back on and increase the temperature it fluff out against the same amount of gravity making gravity less effective. The coldness of space actually helps out gravity making its impact more effective. It doesn't change the force but makes the force more effective. Ironically, using t…

Can you guys point me in the right direction on how to figure this out. How many comets would have to strike the Earth in order to account for the roughly 2x10^21 kg of water presently found on our planet?

As part of the Decadal Survey, which marks plans for future research in astromomy and astrophysics (every ten years, as the name suggests) a lunar telescope is one of the ideas put forward, to study the 'Dark Ages' of our universe, please see the sciencedaily article below... from the article EDIT: May help if I provided a link... http://www.sciencedaily.com/releases/2008/03/080311124548.htm

Is it possible to have a planet made out of water, like Jupiter and Saturn are made of gas? I don't mean like Earth which is just covered by water, but one that is completely liquid, or a gas planet with a liquid core?

Can someone point me towards some links or sources that would help me explain how to estimate the relative age of galaxies and how to estimate the adjacent galaxy's ages. Thank you.