Astronomy and Cosmology

Last night was the 1`st chance to get a picture of the moon, I was using a 1200mm lens with a CCD ratio of 1.7 making it effectively 2040mm. the image is uncropped, and although has a little blur from clouds and camera shake (the SLR mirror is quite strong and moves the cam a bit), it hasn`t turned out too badly for a 1`st try. here`s another one that I took tonight, the Moon is currently Waxing, and it`s neat to see the features as almost 3D at the edges due to shadow detail created by the craters. I`m using a 600mm lens for this shot with the same 1.7 aspect ratio.

Hey guys, I saw a question about that on twitter and I was wondering if anyone knows any organizations/sites that do this. Where can I report a special sighting? Either a fireball or a unique event, or even just sighting something unique when observing the sky either with a telescope or with the naked eye.. Is there a place that collects such sightings? Uhm, please note: this is a serious question. Please don't put anything about UFO Abductions (or similar), since those are not only unproven, but sites that promote them are usually totally uncritical of the data they collect. I'm looking for something that promotes science and amateur astronomer collaboration…

many of the threads which discuss theories of space/gravity etc. use the phrase "space-time". can anyone please give me a simplish definition of this for it is a concept i havent come across at all before. grateful for any response

I simple cant rap my mind around the fact that some quasars are said to be receding at 6 C and are 14.5 light years from earth.? Please enlighten me? Alan

Hi, I have just one "simple" question: Is cosmos(universe) finite or infinite? According to some articles I have read about inflation it seems that inflation theory works only with finite number of particles and finite space. Suppose that inflation "spread" in time - ie. that it started somewhere (in one place or in infinite places) and subsequently (at finite speed) the effect of inflation influenced surrounding places. Let's discuss the alternative that cosmos is not finite - because here we will (I think) get into some trouble: a) Let's suppose that inflation was "started" at bounded volume in (infinite) space. It then follows that: I) inflatio…

Stellar Habitable Zones are defined by: L* / DHZ2 ~ const And, stellar Luminosities scale approximately as the fourth-power of the star Mass (Bowers & Deeming. Astrophysics I: Stars, pg. ~28). Thus, the Habitable Zones of smaller & dimmer stars are deeper down into their parent stars' Gravity Wells: UHZ = - G M* / DHZ ~ M*-1 And so, Interplanetary Space Travel in such systems would require considerably greater (~several times more) Energy expenditures. Moreover, most M-Class stars' potentially Habitable Planets, b/c they orbit so closely to their parent star, are probably Tidally Locked to those stars*, and probably possess no Moon…

Work-Night Rough Draft Stars are born from Giant Molecular Clouds (GMCs), in big "batches" that become -- upon the condensation & dispersal of the parent GMC -- Open Clusters. Now, "stars inside an Open Cluster are at first tighly packed, moving at the same speed around the center of the Galaxy"*. Such Open Clusters typically persist for several hundred million years, before becoming disrupted**. * Open Cluster - Reference Library - redOrbit ** Sun's siblings may have seeded Earth life - space - 26 September 2008 - New Scientist ; cf. http://www.astronomyforum.net/planetary-forums/84613-how-find-suns-sibling-stars-exo-planets.html Now, the Ursa Major Cl…

Why is our universe asymmetrical instead of symmetrical. After all the same quantities of matter and antimatter were created in the moment of the big? Luckily for us the antimatter "went elsewhere" and we live in a universe dominated by matter The matter/antimatter scenario of the early universe should have annihilated each other leaving the universe a soup of game rays, no stars galaxies,etc Alan

I was thinking about the concept of time recently and came to the realization that for time to exist there must be some movement through space benchmark for it to exist. If you consider all the possibilites of the universe as it has supposedly existed from the 'primordial atom' as postulated on a recent showing of the 'Universe' series on TV to the current time and probably way beyond, it seems clear that there has always been movement through space and probably always will be. It would seem that the only way a 'beginning' of time could exist would be that the early universe consisted of nothing. Do we know how long the 'primordial atom' existed prior to …

The discovery that galaxies, or island universes, were exhibiting red-shift in degrees that increased with distance, showed that the universe was/is not static. But it could show that the universe is either expanding, or collapsing, or, more likely, a mixture of both. Why then, and by whom, was it decided to go with the expanding option. Could it have been more acceptable to have "Gods" work grow larger, and perhaps more magnificent, than for it to be seen as possibly collapsing?

Hi. I'm very interested in black holes but I don't know much about them and was wondering if anyone who does know something, or who has any ideas, could answer a question for me. Looking at the curved spiral arms of our galaxy swirling around the supermassive black hole that is believed to be at it's centre, I am often reminded of a liquid going down a plug hole which also has a curved path veering to the right or the left depending on which hemisphere you are in before it goes down the plug hole. It does this because the Earth is rotating, as far as I understand, so would it be reasonable to hypothesize that black holes might also be rotating?

Lee Smolin has a new article in Physics World that will shake some people up. http://physicsworld.com/cws/article/print/39306 It's primarily about time. The idea that the universe actually has a fundamental global time, that its evolution runs on. Even though as we well know from conventional relativity the time we experience is observer-dependent. But the article will also help tone down some of the "Multiverse" excesses of the past several years.

Inspired by the National Geographic documentary Journey to the Edge of the Universe (DVD), it occurred to me, that our visual observations of the Cosmos could, quite conceivably, be sufficient for "retro-dicting" the Known Universe (Causally Connected regions of Spacetime beneath our Lightcone), and "pre-dicting" the Unknown Universe (Causally Disconnected regions of Spacetime above our Lightcone) -- including, in particular, the Modern Universe (what's happening, right now, across the Universe, even though the Light from those regions & events won't reach us for millions & billions of years more). "A picture's worth a thousand words", so please see the attach…

We know that the universe is expanding and the expansion is accelerating, it is also commonly believed that it has been acellerating since a universal singularity existed (the big bang). Assume that instead of the universe having always expanded but it goes through phases of acelleration and contraction akin to a sine function, that would place the current universe somewhere after a trough approaching an inflexion. In this question it does not matter what would cause such an oscillation, but I am curious about what observations contradict such an idea?

I'm sure everyone has heard all about these 2012 end of the world predictions, what i really want to know is, is any of it scientifically true??? take out any religious beliefs, i want to hear a real scientific answer with no bend or twist of any sort of propaganda. Are the planets really going to align? is planet X really going to come and disrupt our planet? Are all these "religious related crop circles" actually real?.... ETC!?!? Is all of this being blown WAY out of proportion or do we all really have something to worry about, and if we do, what can be done if anything??? All of this has really been frightening me, i am no astronomer or any sort of scientist with a …

I am wondering if for example, a spacecraft is a light year away and it is en route to collide with an asteroid. So, it sends the info back to scientist on Earth, which will take one year. When the scientist on Earth receive the data, it will send commands back to the spacecraft,which will take another 1 year. However, wouldnt the spacecraft have collided with the asteroid by then?:confused:

What happens if you give birth to a baby in space? or is it(birth) impossible?

What does your Drake Equation yield? I heard Michio Kaku interviewing a guy working at SETI a couple of weeks ago on his radio program "Explorations". Did anyone catch that? They discussed the likelihood of detecting intelligent signals from nearby stars. The SETI guy, sorry I missed his name, said he didn't know how common intelligent life was, but within the next few decades the SETI search will either find ET(s) or conclude that they are not out there, or at least not transmitting. He was critical of the Rare Earth hypothesis, among other things, explaining how even it Earth had no moon the loose rotational axis would move so slowly that it would hardly pose a thr…

I asked this in a thread in the relativity forum and it got buried and never got answered. Does the separation of matter caused by the expansion of space experience the same time dilation and length contraction as a similar distance change and speed from a rocket ride? I am thinking that if two galaxies are at rest with the CMB but are separating at relativistic speeds due to a increase in distance from expansion, they will share the same time frame. I am thinking that if the two twins blasted off from Earth experiencing equal acceleration but in opposite directions, They also would experience the same time frame. Despite there increasing separation speed. …

if you get a telescope for example hubble and look deep enough into space you see light and images from billions of years ago would it be possible if we looked far enough we could see the big bang?

Im sorry if im mising the plot completely here.... If the universe started at the big bang (or something similar) and then expaned from there, and we know within reasonable doubt how old the universe is then can we not say that the universe is no bigger than light could have traveled during that time (since nothing can move faster than light) ???? Maby im mising something... Thanx

http://www.sciencemag.org/cgi/content/abstract/1172740v1?sa_campaign=Email/pap/21-May-2009/10.1126/science.1172740

Computer Simulations suggest that: hundreds of medium-sized Black Holes are roaming loose in the Milky Way. These rogues... are the orphaned Central Black Holes of the many smaller Galaxies that the Milky Way has swallowed over its billions of years of existence. For: Galaxies, such as our own, most often grow by absorbing smaller, satellite galaxies, such as the Large Magellanic Cloud, which orbits the Milky Way. And: each of the hundreds of billions of Galaxies in the Cosmos formed a massive or supermassive Black Hole at its center [and] when big Galaxies collide -- a relatively common occurrence -- their central Black Holes eventually merge. But: someti…

More accurate measure of supernova brightness means more reliable distances. (Type Ia SNe are used as standard candles.) This will enable more accurate measure of the Hubble rate---the expansion rate/distance ratio basic to cosmology. The SciAm has a news item about this: http://www.scientificamerican.com/blog/60-second-science/post.cfm?id=a-better-way-to-size-up-distant-gal-2009-05-22 ===sample excerpt== the new method can be used to measure a supernova's luminosity, and hence distance, much more quickly, and with a level of accuracy the study's authors say surpasses the traditional approach. The researchers found that the ratio of the brightness of two co…

I was wondering how close you could look at our moon with the Hubble telescope? Could they see the American flag that was put there? If so that would prove to the skeptics that say they never landed on the moon that they actually did.