Astronomy and Cosmology

i have heard that sunspots are colder. does anybody know how cool are they and are they different from each other(in their coolness)does their coolness depend on the stars???

The cover of the October 2008 Scientific American says Forget the Big Bang! The cover story inside is by my namesake, a top quantum cosmologist named Martin Bojowald, and is titled Big Bang or Big Bounce? http://www.sciam.com/article.cfm?id=big-bang-or-big-bounce At the moment it is available free, so if you are interested it would probably be a good idea to check it out. They sometimes put articles on a pay-per-view basis later. As a summary, the SciAm editors identified these as the key concepts, but the actual article has a lot more in it: =====quote==== Key Concepts * Einstein’s general theory of relativity says that the universe began with the big…

Here is an image showing Mt Everest and a Venus mountain compared to Olympus Mons on Mars. However, I've always thought that if Mars once had water, then a great part of Olympus Mons would've been underwater. So it's kind of "cheating" to declare it the tallest mountain among our sun's planets. Here is an image of Earth's Mauna Kea, in case you think the seafloor part of a mountain is used in the measurements. If that were the case, then Mauna Kea would be higher than Mt Everest. So my question is, does anyone know the deal with Olympus Mons? When they measured it, was a pre-existing Martian ocean given consideration? Or does that matter after the ocea…

just give it a look. http://www.robgendlerastropics.com/M31NMmosaicLL.html

On average, largescale distances between unbound-together objects in our universe are EXPANDING. So we have the common way of talking where we say "space is expanding" or "the expanding universe". All this means is that distances are increasing according to a certain law (technically the Friedmann equation, which determines the changing value of the Hubble parameter). Since space is expanding, do you think it's necessary for it to have a larger surrounding space to expand into? That's the poll question. ======================== In case anyone wants it, I'll give some clarification. If this is all familiar to you, don't bother with it, just register your viewpoi…

Are meteor showers the same appearing all around the world? Or say do thy have 'Geminid meteor showers' around the entire world when they occur at the United States?

I have been thinking a new way of unfolding the mysteries of our cosmos! There are these jargons- dark energy, dark matter, visible matter, entanglement, speed of light, black holes, inflation, big bang, gravity, strong weak and electromagnetic forces, voids of space, spacetime etc etc... How do we combine all these into a coherent whole? see more at http://www.scienceblog.com/cms/blog/6797-modern-cosmology-17241.html http://rsridharan.blogspot.com/

Hi all, newbie here.hoping someone can answer my question. I was reading an interesting article about dark matter. It mentioned about clouds of gas in deeps space being millions of degrees kelvin therfore giving off x-rays which in turn makes them visible to x-ray telescopes. I couldn't quite get my head round the idea of gas floating in the vastness of space at near absolute zero being at such high temperatures. I can kind of understand gas being hot from an exploding star/nova or being dense enough itself to form a star,but not why in such freezing temperatures it remains hot. Probably something obvious I'm not thinking of! I kind of imagine the gas being not too…

This is an attempt to capture a "typical" day in the life of two astrophysicists... Not trying to "jazz things up" - just show people what it is like and why people love doing it! The two people involved study gamma ray bursts... Would be interested to hear what people think?

First post, I love science, always have. Im frustrated after 15 minutes of searching for a simple answer... Who was it that calculated solar output back appr. 1850's maybe? He used a watch, a block of ice, and the AU. Just a real neat story of the power of observation, i saw it on TV awhile back id like to know his name. Thank you.

That's the intro key concepts from a Scientific American article titled The End of Cosmology? The article goes on to explain that most of the universe will disappear from view, and asks "what has the universe already erased?" Surely many here are familiar with this, but I'd like to hear your thoughts on it.

So if the universe has a finite size, which i had previously, previously meaning way in the past, heard it didnt, what is outside the universe? Is there any mathematical proof or such or just wild speculation? It seems very confusing that there is something outside the universe, i mean what would it be like and such? It must just be my tiny incompetent early 21st century mind........

What if enough dark matter was concentrated in an area, becoming ever large, will it collapse into a black hole? And if so, wouldn't it just become a normal black hole that couldn't be traced back to its dark matter origins? Can dark matter from into bodies like stars/planets do? Such bodies might emit dark energy.

Or so they say... http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/09/08/hadroncollider108.xml And the Earth was not swallowed into a mini black hole! http://public.web.cern.ch/public/

I am told the term topology is incorrect in this context and the correct usage would be, "The universe has a four-dimensional topography". Which is correct and why? What are the differences? Feedback is appreciated, thanks.

We know that Vostok1(not sure,may be vostok2) has gone out os the Solar System.But it should have contact with the Earth like,when it was inside the Solar System. But why it is not having contact with the Earth..

I have read that Universe will go on expanding(Big Bang Theory).At one stage the expansion stops and the universe will shrink again(Big Crunch theory).Is it true ???

Is Proxima centauri our nearest star?? My book says it is Alpha centauri

Hubble space telescope is able to capture a picture of a collision between two galaxies, 2.5 billion light years (reference-a newspaper)away from a place near the Earth,isn't? if it is near pluto or somwhere it can capture pictures far off,isn't?

Is it a star or a constellation or a galaxy

Is this for real? Scientists in 1997 claimed that the earth was being bombarded with upto 43,000 dirty snowball comets a day. "Tiny Comets May Have Huge Impact" http://query.nytimes.com/gst/fullpage.html?res=9505E7DD123AF93AA15756C0A961958260&sec=&spon=&pagewanted=all I'll admit... it's getting really hard to find the truth... the only reason why I thought the whole dirty snowball thing was a fake was because NASA has a stardust program which says comets are not made of dirty snow... "Stardust Findings Suggest Comets More Complex Than Thought" http://stardust.jpl.nasa.gov/news/news110.html If anybody could help me keep my sanity for a bi…

http://www.washingtonpost.com/wp-dyn/content/article/2008/08/26/AR2008082603101.html During its first 95 hours of operation the new instrument produced a map of the gammary sky. When they launched it, the name was GLAST for gammaray large array space telescope. Now that it is in operation it has been renamed Fermi, after the physicist Enrico Fermi. Here is a Scientific American article about it: http://www.sciam.com/article.cfm?id=glast-telescope-first-light Here's the NASA website for the Fermi Space Telescope http://www.nasa.gov/mission_pages/GLAST/main/index.html Things to notice are that while the Hubble Space Telescope was designed to see in o…

In another thread, Arch made this argument. there are challenging issues here (or so it seems to me). I want to take it out of context and focus on it in this separate thread. I think the word "create" here is a bad choice. the present derives from the past. conditions and events of 2008 derive from events of 2007. it gives the wrong idea to say that 2007 created 2008. but I don't want to worry about wording. there is something more substantial. It is about what we can know. In some sense we cannot know the past. The dinosaur bones might have been buried in the ground by aliens with a sense of humor. We can only make probable inference about the past. …

Same qustion as the tittle.

Others stars contain sunspots,don't they??