Astronomy and Cosmology

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.

About 10-15 years ago we had a family holiday. My father and I were lying in a dark room in 2 seperate single beds talking about the day. Just as we said goodnight, there was an intensely bright white/silver flash that started at a point just off centre from the middle of the room and grow to the size of grapefruit. It dissapeared instantly (the whole thing lasted but a split second). We BOTH saw this and my dad was amazed and said "what the hell was that" We did not know. Could this have been a cosmic ray? Do they reach us here on earth? Has anyone else seen anything like this? Interested in your views.

Okay, I know the universe is expanding faster then the speed of light, so I have a few questions. Is it possible that there are galaxies out there that even when they emit light since they are traveling faster away from us then light is traveling toward us that we never see them. Also, is ALL of space expanding at this rate or just the edges? I really don't understand how that works either. And since space is expanding when we measure the distance from one place to another using light sources are we taking into account the expanding universe? Thanks, from a n00b.

"But that leads to a question — are we sure that gravitons wouldn't be emitted at the event horizon?" Indeed, and would someone be wrong in assuming that the event horizon signifies the edge of the black hole? Or is it just the central point of a greater structure in which all the stars and planets fit into (that structure)? For instance, we do not observe any bodies spherically orbiting our sun, (within the inner solar system) rather the bodies orbit upon the plane. And one would be rightly entitled to think that if any bodies did occupy a spherical orbit, that orbit would need to be close to the sun (ie the spherical orbit of a satellite orbiting Jupiter, say, wou…

About 3-4months i bought my first telescope (Celestron Firstscope 90 EQ) and ive been trying to grasp how to make my way around the stars using star charts. I can't make much sense of it. I know the main constellations and I'm familiar with the night sky in London. I understand about star brightness and their symbols but could someone please outline simply and orderly how exactly star charts work with coordinates. Also with my new telescope how do i apply the star chart coordinates to my telescopes equatorial mount.

http://www.sciam.com/article.cfm?id=information-may-leak-from Read the article, and tell me, couldn't we use these black holes as a sort of time capsule were we would drop in information (somehow) and it would be continuously streaming out of the black hole?

Can you guys help me figure out how long it would take for a radar signal to travel to mercury and back when Mercury is at its closest point to Earth?

http://news.bbc.co.uk/2/hi/science/nature/5388690.stm 1 billion euro project to build the most sophisticated radiotelescope system in the world (Square Kilometre Array (SKA))will be built in either South Africa or Australia. Which do you think it will be? Some of the factors to consider include astronoical, geographic, socioeconomic and political.

This is my first post on the science forums. I think it's wonderful that I now have somewhere to discuss science related topics in a forum designed for such a thing. I posted here first as I will probably do most of my posting here and in the genetics forum. I am relatively new to learning about Astronomy and Cosmology. I am reading through Carl Sagan's books as well as Stephen Hawkings. Loving every moment of it. I am probably by far not the most knowledgeable person here but I will do my best to learn, discuss and maybe even teach at some point when I get more comfortable. See ya around

I was always tought that all the planets in our solar system were orbiting the sun because of gravity, but after learning a bit more about the fabric of space from a book, I was thinking that maybe the planets are kept in orbit around the sun because of the enormous indent made by the sun's mass. Am I correct? But if that were true, wouldn't all the planets eventually sort of slide down into the sun like a...flushing toilet...

I've been playing with the Drake equation by applying it to each individual star and only progressing the equation to the next stage if the previous stage allowed for it. My reason for doing this is to see what difference it makes when each star is treated as an individual that doesn't know that the intelligent communicating life quota has allready been met. I ran the program a number of times for each set of values and each number of years to get a minimum, maximum and average. In fact the first values at 10000 years quite often produced a result of no civilisations but I restricted the minimum to one since we know there is at least that many. I used the followin…

Great reading. quantum cosmology.pdf

When we look into the night sky we are looking back in time, for we do not see the Universe as it is but as it was. If, for example, we look at the Andromeda Galaxy - I believe it is something like 2.2mil Ly away - the light from Andromeda takes 2.2million years to reach us. Thus we see an apparent universe. Because it takes light time to travel the Andromeda Galaxy may have exploded 1million years ago but we wouldn't know for another 1.2million years. Consider: Six billion years from now we receive a communication from a region of the universe six billion light years away. The communication is a map of the Universe and the apparent distribution of galaxies as see…

Cosmology is based on General Relativity, which allows distances to expand and many times the speed of light. Do you believe this? Show your opinion on the poll.

I read an article on the New Scientist magazine, and in this article an astronomer/cosmologist by the name of Laura Mersini-Houghton claims to have found evidence for the existence of another universe. I'm not sure how well known this is among you guys, but a little while ago astronomers discovered a huge void, about 1 billion light years across in the constellation of Eridanus. So far, it remains the biggest known void in the universe, with very few stars and galaxies in that region. The reason I brought up the void is because this astronomer believes it to be actual evidence of another universe. Indeed, this seemingly large void even shows up on WMAP and on th…

I know her mainly from her book "A Madman Dreams of Turing Machines," but hey, she's a physicist, and is now publishing a podcast on cosmology called "Reports from the Cosmos": http://www.jannalevin.com/podcasts.html

Anybody going to see the total solar eclipse in Shanghai July 2009? More than six minutes of totality! Anyone know of a group of Americans or other English speaking groups that are going? I am interested in joining or organizing a group for travel to Shanghai for the event. Jerry jerrywickey@comcast.net

I remember reading a theory (but unfortunately I forget where) that the Big Bang could have been kick-started needing only about a kilogram of matter, and all the resulting matter and energy in the Universe is the result of an equation between matter and energy and zero-point energy not actually being zero. Is anyone familiar with this idea? I'll have to try and find which book I found it in to explain it a little better, but can anyone expand (heh, pun) on this concept?

Does anyone know where I can find the info to this: How many degrees of arc does a star move in an hour? Also, does it matter how far north or south the star is.

Not really sure if this is the right place for this question but im sure you guys can answer it. For the question im going to use a hypothetical situation: say you have two small objects, like two apples, out it the middle of space very close to each other, and very far from any other object. because the closest objects are so far from these two apples, there would not be much other force (like gravity) effecting these two apples (right?). So my first question is would the gravitational pull from these two apples pull the apples together, or perhaps cause them to start orbiting or something? Or would Inertia prevent these two apples from pulling together? i Asked…

That's what it says here. This is kind of old news, 2004. Interestingly, they don't mention anything about superfast inflation, just the aggregate growth exceeding light speed. Then again, this is 2004. I checked out the WMAP website, and while it did not confirm this conclusion, it did offer another good resource for explaining everything related to expansion. http://www.space.com/scienceastronomy/mystery_monday_040524.html http://map.gsfc.nasa.gov/

Is it correct to say that" if we reduce the normal forces acted upon us nd other bodies to zero,than the whole universe will reduce to small lump?