Astronomy and Cosmology

http://www.space.com/27059-jupiter-moon-europa-plate-tectonics.html Very interesting article. I would like to see your comments. How did Europa formed in the first place and how is this possible?

In Malaysia syllabus(I hate it), we are just going to learn about the Sun during Form 3, 15 years old. Different books provide different answers. The textbook is not reliable(no explanation provided/clear line drawn between solar flare and prominences), reference books give different answers and all 4 encyclopedias of mine yet give a very complex answer but still making me confused. So, I am going to ask experts in this forum for help. (This is not homework, so I am not going to start this topic in the Homework section) Questions 1. Where does solar flares, prominences and sunspots occur?-Corona? chromosphere? Photosphere? 2. When does solar wind occur? 3. What …

Recently, ESA space probe Rosetta had finally approach comet 67P. But tracing its history back, Rosetta have been in space since 2004-which means it was launched 10 years ago. My question is why it takes so long to trace just one comet, why not simply launch just years before the comet approach astronomers` desired orbit and then only launch this space probe? Sorry for grammatical errors.

Earth is about to have a close encounter with a house-sized asteroid on Sunday (Sept. 7), when a space rock discovered just days ago will zoom by our planet at a range closer than some satellites. Similar in size to the Chelyabinsk meteorite that exploded over Russia’s Ural Mountains region in February 2013, Nasa says we will have a ‘very close’ shave – but that there is no risk. (link removed by moderator)

Astronomy isn't one of my big areas, but none the less i find it interesting. One thing I particularly enjoy about it is dark matter, and how we really don't know that much about it. But do we need dark matter? From my understanding, we use the dark matter to help explain why galaxies are able to remain the way they are, as there isn't enough normal matter present to be able to hold the shape that they are seen to hold. But are there alternatives to dark matter that could still predict a stable galaxy in the way dark matter does? All response are appreciated!

would a telescope looking forward on a speeding rocket see the distant red shifted galaxies with less shift? If the speed of travel was close to light, would a telescope see previously unseeable galaxies, past the normal light cone limitation? If a ship were to travel at or above light speed, would it be able to see the BB?

Which way is geographic south of the Earth pointing at the WMAP ?

Hi, yet at school I was thinking about several questions which so far have not found a satisfactory answer. Probably not once one has it erected. Perhaps here is a good opportunity to clarify these issues? 1. Centre of the Universe: We observe far objects rushing away from us in any direction we do the observations what suggests, the move away from each other and consequently from some alleged center i.e. area or point the matter was concentrated earlier. On the other hand, the further the objects we observe the closer to the beginning of the Universe we are. The most distant observations are dated back 14 billion years, which is relatively close (100 million years as…

I never have had telescope in my life. Because of children who wants to look at sky, stars and moon, I want to buy one. Since Im amateur I wants your help. What kind of telescope should I buy? Any suggestions? And my second question is, when I buy it, what then? Im mean sure I could point to the moon but thats it. Any advices, suggestions, idea...anything. Im open for all. Thanks in advance.

what do you think about "findings"(?) of fossils inside the meteroite, are they for real? I search about astronomy in general then i stumble on these sites. http://sdcc3.ucsd.edu/~ir118/Leiden2010/Hoover_JOC_MS.pdf http://blogs.discovermagazine.com/badastronomy/2011/03/05/has-life-been-found-in-a-meteorite/#.VABZ7cV_v-t https://microbewiki.kenyon.edu/index.php/Bacterial_Fossils_in_Meteorites http://www.dailymail.co.uk/sciencetech/article-2292042/Second-study-finds-extra-terrestrial-fossils-meteor-fragment.html im mean recently we found plankton living outside of space station...

According to my (often suspect) calculations, it appears that no object is able to orbit Phobos, the inner moon of Mars, without being continually pulled in by Mars' own gravity field. Even the situation with the outer moon, Deimos, is a close call in this respect. I wonder, though, if I've got my maths right. This being more than possible, I would welcome any help or advice. Many thanks. PS. I am aware that maintaining a freefall orbit round either moon would be problematic in any case, given the varying gravitational fields resulting from their irregular dimensions. I'm ignoring that for now.

Wikipedia reports the velocity of the Sun as, What does that mean?

By simple mechanics, no free macro body can orbit around another moving macro body in any type of closed geometrical path. Yet; (1). Knowing sun is a moving macro body, why do we perpetuate circular/elliptical planetary orbits around the sun, in all text books and other literature? (2). Knowing earth is a moving macro body, why do we perpetuate circular/elliptical orbital path for moon around earth, in all text books and other literature? Planetary laws are derived from relative positions of few planets about a static sun. They are good enough to predict relative positions (and cyclic phenomena related to relative positions) of macro bodies in a planetary system…

Hey, I am very interested in space related stuff and also for all the things that are being developed and if there is anything new there, then I read it immediately but in have a few questions. Well, i've read so much that many projects have been deactivated and that also currently the financing of such projects is a problem. But I also do not know if it is a good idea, because we do not have a huge knowledge. So, here are my questions: 1. Will there ever be possible to fly with an approximate speed of light or is it not (even) possible? And there are many people who think that worm holes or something like that also provides a quick trip. As far as I know, it's even a …

I am interested in cosmology/astronomy, but only as a hobby. I constantly find some very helpful sites to further my knoledge in the subject and am going to post them here for anyone to view, so there in one place. Hope its useful. If anyone wants to post any useful links too, please do. This is the best website ever. They have textbooks and academic reads in every subject. http://www.freebookcentre.net/ Mainly for kids, but has astronomy games and info. www.kidsastronomy.com Free online astronomy courses on Coursera. https://www.coursera.org/courses?search=astronomy ASTRONOMY TODAY www.universetoday.com I have found three d…

Does anyone think it would be timely or worth sending up another vehicle, launched on an interception trajectory of the current voyager craft, to relay between the craft and NASA? The mission is set to end between 2020 and 2025. Sending up another craft outfitted with equipment to relay would allow the vehicle to continue sending back useful information about interstellar space. Shutting down systems could conserve power on the craft. Extending the range would allow us to communicate with Voyager longer than anticipated. Building and waiting 30 years or so to get another craft that far would be Cost prohibitive and delay our continued research in space. Thoughts.

I am an amateur scientist with a lifelong interest in Mars, and I recently finished my essay, "An Interpretation of the Geology of Gale Crater and Mount Sharp, with Implications for the History and Habitability of Mars," wherein I present a new hypothesis for the geology of the complex, and (re)introduce a lacustrine model (lake-bed sedimentation) for the strata comprising the Lower Formation of Mt. Sharp, which is something that has recently fallen out of favor (the aeolian or "SWEET" model is in vogue, but I find numerous faults with that model, and believe I have addressed all criticisms of the lacustrine model). I also argue for a near-surface aquifer and geologically…

Type Iax supernovae normally creates zombie stars which survives a cataclysmic supernova. May I know more about them? How does it survive? Is it a white dwarf? Or some other celestial bodies? Recent related news: http://www.latimes.com/science/sciencenow/la-sci-sn-nasa-hubble-zombie-star-20140806-story.html

After viewing a topic discussing the big bang, I started to wonder on how the event got this name... During the start of expansion, it couldn't of banged at all seeing as it was sorrounded in 'nothing' (i'm relating this point to the sound of a bang, nothing else). It wasn't at all big... The start of the universe must of been infinitely small. Ofcourse, this name is obvious today - the universe is the biggest 'thing' known, and using radio, can be heard as the bang is still going on. So yes, the name fits today, however, not at the start of what was the big bang.

I've looked in a lot of places for a clearer explanation of the expansion of space but either I get psuedoscience or the typical balloon analogy, so i'm hoping somebody here is more used to this concept. I'm stuck with how space can expand. Like say I have a 3 dimensional space and attach a coordinate system to it, sure I can make the coordinate system larger or smaller, but how does that mean the space itself is smaller or larger? In my cosmology class we've done the scale factor and co-moving distance thing, where r(t)=a(t)x, where a is the scale factor and d is the co-moving distance, and this just flummoxes me, conceptually, completely. I'd be very happy if some…

I realise there's a handful of physicists working on an effective QFT for gravity, and there are a number of attempts at attacking dark energy at the quantum scale via QED vacuum (I'm sure there are probably other suggestions). However the few papers I have read require an ad-hoc addition to explain present day cosmological acceleration using this approach (I guess akin to a cosmological constant), unless somebody knows better. My questions are; is a solution for quantum gravity required before a QFT for dark energy can be solved (the effect of which is much weaker than gravity), i.e are the two possibly intrinsically related, or do the current proposed mechanisms for…

Hello you all! A bizarre idea, maybe it would fit in the "speculations" section better than in astronomy... Could a gamma ray that arrives near the horizon of a black hole produce a particle pair? To my rudimentary understanding, the electric field of a heavy nucleus separates the particle and antiparticle created there by a gamma ray. Hawking radiation as well separates them, but without the initial gamma ray, just through the strong curvature of the gravitation field there - that is, in my naive and probably wrong representation, the virtual particle falling gains more energy than the rising one thanks to the curvature, and if this gain is big enough, excee…

Observations of all other space's, have a limit to what can fit into them, to a point where nothing added other, can fit in. Except astronomical space. What is this space? It seems to be a vast and endless void, where countless of solar systems can not only fit in quite comfortable, but can travel within it with relative ease. How could it be so vast that it's big enough to hold an event that hadn't taken place yet in advance, (Big bang theory). Take into account "Dark" matter/ energy which is theorized outside of traveling light being bent by it, what is it's relation to space, is it the fabric of or just another substance that popped up like we have been theorized too.

I read somewhere recently that the atmospheric pressure on Mars is equivalent to that on Earth at an altitude of some 35 (miles/km?). This being the case, would the Martian atmosphere still be dense enough to burn up small incoming meteors? Many thanks.

A few days ago I read in more depth about Schrödinger's Cat. The thought experiment in which, if you put a cat inside a box and rely a deadly hazard on the quantum state of an atom, there's a 50/50 probability for the cat to be either alive or dead, which is uncertain until someone observes or measures which of the two things has happened. So I thought to myself: How would this concept apply to something even greater... like planets, and life on other worlds? After all, there's countless processes involved in the the formation of planets which could be influenced by the quantum state of various particles. For example, what if a sun reaches a point where it becomes so …