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Astronomy and Cosmology

Topics related to observation of space and any related phenomena.

  1. Started by JHAQ,

    I know all the current thinking & evidence on the origin of the universe is the Big Bang theory but why , with such an immense amount of matter & energy was not the energy for expansion of any mass within it infinite & why was it not a vast black hole in its early stages ? Infinite means infinite as per Einsteins equtions -- or does it ?

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  2. Started by MidnightFox,

    Ive been thinking a lot. I dont think any of the theories work. The Big Bang Theory says that the universe just suddenly is created by one atom and time and space was not created. The Steady State theory says that it has been expanding. The other one( that elctro thingy) says that it is made from electricity and magnetism or something. Any1 got a clue how the universe began because i dont agree with any of these theories!!

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  3. Started by h4tt3n,

    As far as I know it's a commonly accepted fact that the earth is gaining 100 to 200 tonnes of mass / day because dust and small meteorites hit our planet. This happens mainly because it "gets in the way" and is scooped up by our planet like snow on the front side of a driving car, rather than beeing sucked in by the earths gravity. Since earth apparently grew much faster in its earlier stages, billions of years ago, I suppose the growth rate has been slowly descending as our solar system has been sucked clean by Jupiter and the other planets. But how fast has it been growing over - say - the last billion years? Was earths gravity notably smaller in cambrium or the cr…

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  4. Started by Gilded,

    "there are no features that distinguish one black hole from another, other than mass, charge, and angular momentum." (http://en.wikipedia.org/wiki/No_hair_theorem) Electromagnetic energy transfer happens through transfer of photons, right? And even photons can't escape from a massive black hole. How is it possible to measure the black hole's charge? Are my fundamentals all wrong again or am I missing something very important here?

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  5. Started by Guest_Jim*,

    The Hubble Constant is the rate of expansion for the universe and according to a new study maybe off by as much as 15%. This may not seem that big of a deal but it is since this is needed to estimate the size and age of the universe. Here's a link to a podcast about it that has links to more information. http://hubblesite.org/explore_astronomy/skywatch/#66

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  6. Started by blike,

    A creationist friend of mine is claiming that the reason we see distant starlight is because there was a rapid expansion of the universe at creation. The universe expanded for about 2 picoseconds to its present size, and lightwaves along with everything else were stretched. This, he says, explains the redshift of distant galaxies. The farther the galaxy, the more expansion had to have occured, the more redshift (stretched light) we see. Is there a way to test this idea? I'd imagine there's got to be a way to measure the spectral emissions of distant elements, note the redshift, and calculate what kind of expansion could have created this redshift and see if it correl…

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  7. Started by GutZ,

    I don't know if this is the right section for this...I apologize if it's wrong. Nova: Magnetic Storm http://www.pbs.org/wgbh/nova/magnetic/ Transcript http://www.pbs.org/wgbh/nova/transcripts/3016_magnetic.html "There's a region of our planet that no human being has ever visited. No one has ever seen this place, yet what happens here affects every one of us every day of our lives. It's 2,000 miles beneath our feet, the Earth's molten core. Here a vast ocean of liquid iron generates an invisible force, the Earth's magnetic field. It's what makes our compasses point north. But it does a lot more: it helps to keep the Earth a living planet. Our neighbors, Venus…

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  8. Started by ajb,

    I wanted to know if any of you are members of an astronomical society? Joining a society is a great way to learn new skills and to spread ones interest in astronomy. Maybe members would like to post links to their society? I am going to join the Manchester Astronomical society, which is one of the oldest societies in the UK. http://www.mikeoates.org/mas/

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  9. Started by kragg,

    I recently saw the documentary, The Great Year, and toward the end they bring up the idea that our sun is actually part of a binary star system. Our astronomy class never covered such a concept, and the idea boggles my mind. Could this be true?

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  10. Started by BobbyJoeCool,

    Is it possible for there to be a "twin-planet" situation? So that, a so called "planet" and it's satalite of near-equal size would orbit eachother in much the same way that binary stars do in binary systems? Just a thought...

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  11. Started by Rajdilawar S,

    I am from India and want to do certification in Astro Physics, but here in India there is no such organization offering so... Can you please give me any link of any such University/Institute/Organization offering the same online or via correspondence? I am very much keen to do same. Please also provide me some web links too...

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  12. Started by [Tycho?],

    http://news.bbc.co.uk/2/hi/science/nature/5407038.stm Yikes! Those planets must be incredibly close to their stars to be able to make such a quick orbit. Well I just tossed out a quick calculation, with a period of 1 day, a planet the mass of 10^27kg (around that of jupiter) around a star of mass 10^30 (around that of the sun) I get a semi major axis of just over 2 million km (!) and an orbital velocity of 27 000m/s (!!). I have to think that planets in such a position much have fairly short life spans, as massive as they are they must be getting a ton of their mass blown off by solar radiation. Or maybe not, what do I know.

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  13. John C. Mather and George F. Smoot are our newest Nobel prize winners in physics! unofficial rumor, have to confirm yeah! http://www.bloomberg.com/apps/news?pid=20601085&sid=a8k2ZYLGNxTE&refer=europe http://nobelprize.org/nobel_prizes/physics/laureates/2006/index.html The Nobel Prize in Physics 2006 "for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation"

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  14. Started by chitrangda,

    hi! Do u know that U.S.A has 413 satellites in the space while the rest of the world has only 382 all put together. The figures released by the union of concerned scientist provides datails on some of the Pentagon's most secret satellites. The Russians, who follow U.S in otal number,have 87.The Chinese have 34. can any one tell that rest of the satellites belong to which countries???????? plz try finding i couldn't find!

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  15. Started by Martin,

    http://www.arxiv.org/abs/astro-ph/0606266 Ellipsoidal Universe Can Solve The CMB Quadrupole Problem Campanelli, Cea, Tedesco Physical Review Letters, 29 September 2006 Physics News Update has an item about the Campanelli et al paper http://www.aip.org/pnu/2006/split/794-2.html?source=rsspnu would be very strange if it turned out right like Kepler for years everybody is assuming circular or spherical symmetry because that is almost right, and then some dude comes along and notices that it is not quite circular it is more like elliptical whoah! and this explains something about the CMB? maybe someone would like to discuss this.

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  16. Started by Martin,

    this is not a puzzle in the sense of a game or riddle. It is a fact from astronomy that (if it is not already familiar) you might want to think about and get to understand In ordinary experience with earth-based geometry, the farther away something is the smaller it looks. That is true for short distance geometry done with metal rulers and yardsticks on the earth surface. But it is not true in space for very long distance geometry. In ordinary shortrange geometry there is even an approximate reciprocal relation between angularsize and distance that works for objects with small angular size. If it is TWICE AS FAR then it looks HALF AS BIG. If you double the dista…

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  17. Started by chitrangda,

    can any one tell the formation of "white dwarf star"?

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  18. Started by Martin,

    they haven't FOUND any habitable extrasolar planets the new NASA study just assesses the chances of eventually finding earthlike planets in systems with hot Jupiters http://news.bbc.co.uk/2/hi/science/nature/5325476.stm BBC: "Earth-like planets may be common" blog comment by astronomer (who partcipated in the new study) http://scienceblogs.com/catdynamics/2006/09/exotic_earths.php SEED magazing article: http://www.seedmagazine.com/news/2006/09/several_planetary_systems_may.php The main article got published in SCIENCE magazine, current issue 8 September. that is pretty good. Science magazine has decent editorial standards. Exotic Earths: Formi…

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  19. that "planette" bigger than Pluto, which Mike Brown of Caltech discovered and temporarily nicknamed "Xena" has now been given its official name, as has its little moon. As discoverer, Mike got to pick the names. It went into effect 13 September, yesterday. there was a circular sent out from the IAU Central Bureau of Astronomical Telegrams. As of today, the Wiki article has already been corrected http://en.wikipedia.org/wiki/136199_Eris Here is yesterday's announcement: scroll down to the dwarf planet section at http://cfa-www.harvard.edu/iau/Headlines.html or click directly on http://cfa-www.harvard.edu/iau/special/08747.pdf Eris is the Greek god…

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  20. Started by J.C.MacSwell,

    How is the momentum of the expansion thought to be measured? Assuming there is enough matter present to create a "big crunch" is it assumed that space will "shrink" (or slow in expanding, stall, then shrink) to the same beat as would be consistent locally with a gravitational collapse "in" space?

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  21. Started by mombasa,

    Hi all, This might seem a silly question to you all, but what exactly determines the mass of an object, specifically the earth? Does the earth's mass include ALL its contents, i.e. does a new born baby contribute to the earth's overall mass? What about plants, cars, buildings etc. Are they all included?

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  22. Started by Norman Albers,

    It looks to me like the Schwarzschild metrics of a black hole (BH) yield a negative quantity for the square of light-speed for transverse waves inside the event horizon, and this says to me that they cannot propagate. Is this accepted understanding? Radially things are positive, at least.

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  23. Started by Anjruu,

    Hi. I was reading a book recently, and it mentioned the Kuiper Belt, a big cloud of asteroids around the solar system, similar to the asteroid belt, but farther out. I was wondering what the difference was between this Kuiper Belt, and the Oort Cloud. There was a description in the book (Worlds Without End by John S. Lewis) but it didn't really explain much to me.

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  24. Started by Jacques,

    Hi all This weekend a man made satellite will crash on the moon surface and the flash created might be seen with a backyard telescope. Western united state are favored. http://sci.esa.int/science-e/www/area/index.cfm?fareaid=98 I think that may interest some people here !

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  25. http://www.guardian.co.uk/uklatest/story/0,,-6035526,00.html I think they made a mistake but I am glad they finally decided. The Prague conference of astronomers demoted Pluto

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