Astronomy and Cosmology

Apparently, during a Martian winter, sand particles can get stuck together and frozen carbon dioxide will cover them making a sort of "forest" from these structures. http://www.bild.de/BILD/news/2010/01/13/nasa-fotografiert/doch-sind-das-wirklich-baeume-auf-dem-mars.html

Chuck Lineweaver and his student Tammy Davis did everybody a big service by publishing a SciAm article covering the most common popular misconceptions about Expansion Cosmology (misnamed "Big Bang" Cosmology by someone who didn't like it.) the article is used for the Princeton basic course, so it is online at the Princeton.edu site, and also in a slightly tattered version it is still online at the SciAm site. To avoid making the worst fallacies, and wasting everyone's time, please please pretty please everybody who wants to discuss Cosmology make sure they either have read the article or already avoid making these very common naive mistakes. If somebody keeps …

I was just thinking, the LHC is supposedly going to kill us all right? Maybe the Norway Spiral has something to do with the LHC making it's first collisions? They are in the same general area and the dates sort of fit together. I have a hard time believing it is just a rocket that created such a beautiful but mysterious object.

It is stated in most scientific texts that what ever goes into a black hole never comes back out. I was wondering if this is absolutely true. Is it not possible that it just takes a very long time and then suddenly all of the mass that has been "gobbled up" by the black hole will suddenly be ejected? Are there any known instances in the universe of areas of space that spew mass? If so, could these be former black holes?

I never really liked the notion of the universe expanding, it leads to so many misconceptions. Think 4-d and think about space-time cuts into space and time. The ideas of expanding and what it expands into just go away. Relativity 1.01 think 4 dimensionally! The analogy I like is the cone. Lets cut out the conical singularity. Then globally the cone looks like a circle times an interval (part of the line). Orientate it so that the smaller circle is facing down. Now do some space-time cuts, that is cut up the cone into a series of circles. You see that they are all of different sizes. Now for the analogy. Imagine that the cone represents space - the circles an…

Read it all here: http://www.universetoday.com/2009/11/30/the-next-generation-of-heat-shield-magnetic/ This heat shield idea does make a lot of sense. When a craft enters the atmosphere, it generates heat from the immense pressure of reentry. When this happens much of that super-heated air becomes plasma and is able to be influenced by magnetic fields. Did I describe this accurately enough? Also, in the diagram on that site, the magnetic coil looks like a simple solenoid. Was this coil shape simplified for the causal reader, or is this the actual coil design? Or is it's because the coil is a superconductor it will provide a diamagnetic field? Merged post fo…

Hi, I would love to join your discussion forum, cosmology is never far from my mind, and I love to theorize about the Universe and all that. Another interest of mine is amateur fusion, I have a small lab where I can carry out small high voltage/vacuum experiments. I often like to bring up new ideas and hypothethise about new theories, I hope you guys are open to that. (not like those "standard model Nazi's" at the PhysicsForum ) Let logic and reason prevail Steven

According to mainstream science, the entire universe is generally agreed to be "flat". Just how do we know that it is flat? How does the data from COBE allow cosmologists to conclude that it is flat and not, say, donut shaped?

Fig. 21.16, on page 893, of Carroll & Ostlie's Intro. to Mod. Astrophys. [1st ed.], shows that (1) for stars more massive than [math]2 M_{\odot}[/math] (A5), Specific Angular Momentum (L/M) increases as M2/3; and, that (2) for stars less massive than said same value, the star's S.A.M. increases as M5 (with the deficit probably borne by planets, according to the caption). We seek an order-of-magnitude calculation, which can indicate some sort of suggestion, as to the origin of this [math]2 M_{\odot}[/math] threshold. S.A.M. for massive stars Please ponder an idealized Giant Molecular Cloud core, of constant density, from which a spherical fragment begins…

Dos vidanya, Apophis! http://ph.news.yahoo.com/ap/20091230/twl-eu-russia-asteroid-encounter-c8e2916.html

T Pyxidis, estimated 3000 lightyears from us, is being presented in science media as a potential supernova. I'm not sure this is right, or that it will be confirmed. But I respect Steinn Sigurdsson. He's a reputable astrophysicist. In my opinion reliable and hardhead, not a speculator. Judge for yourself from his other blog posting. Here's what he says about the T Pyxidis news: http://scienceblogs.com/catdynamics/2010/01/has_a_supernova_type_ia_progen.php The reports come from a group at Villanova University led by Prof. Edward Sion. What I get from this is that T Pyxidis is extremely interesting but most likely far enough away not to pose a threat to Earth, alt…

http://backreaction.blogspot.com/2009/06/shrinking-betelgeuse.html Giant stars have a short lifetime. Consume their fusible elements rapidly. When there is nothing more to fuse, they start cooling and shrinking, then collapse and blow. Interesting to study the shoulder star Betelgeuse (alpha Orionis) with that possibility in mind. It is close enough that instruments can actually resolve it and can measure the diameter by a couple of different methods. Diameter measurements by different teams over the course of fifteen years or so show a downtrend. This could be part of a cycle--and destined to reverse itself. Or it might continue shrinking. At the mom…

http://audio.wnyc.org/radiolab_podcast/radiolab_podcast081208.mp3 According to Mr. Green our universe is a quantum flux in the the inflaton field... and that section of the field gave up its energy to kickoff our universe. Could the expansion of the universe be thought of as an injection of entropy into our universe to dilute the energy enough to allow it to fall back to ZERO charge? so it may just dissolve to nothing some day? no hope of anything left behind. I know i am very layman i know... just trying to understand.

http://planetquest.jpl.nasa.gov/atlas/atlas_search.cfm?&Sort=DiscDate&SortDir=DESC FYI, five new exoplanets were posted today, for a total of 19 so far this year.

Spirit is apparently stuck in a sandy bit of Martian soil: http://marsrovers.jpl.nasa.gov/newsroom/pressreleases/20091231a.html Dust may continue to accumulate on its solar panel while it is stuck, until it no longer functions.

http://www.boston.com/bigpicture/2009/11/martian_landscapes.html?amazing All these Mars landscape shots are incredible and astonishingly beautiful. Some are taken from over the polar icecaps Apologies if somebody already posted link to these.

As the earth spins, lines of force facing the sun are 'compressed', and 'expanded' at the umbra. http://www.biocrawler.com/w/images/1/19/Magnetosphere_simple.jpg Does it mean they are constantly changing its position and shape as they pass from a compressed state at noon, to dusk, to midnight, to dawn ? Do they cyclically deform and also rotate ? Question number two... Electrical wiring in orbiting satellites are constantly crossing magnetic lines from the earth field. Does such generates 'stray' currents in their circuitry ?

Does space go on forever, or does space end? There is a "big" difference, if any way you go space goes on forever or if any way you go space ends. What is a "big" difference between those two ideas? If space goes on forever any way you go, space does not have a shape. If space ends any way you go, then space can take a shape. Space can take a shape, if space ends. There is another "big" difference whether space ends or not. Can you think of what that is?

See those letters in the sun glare? I have two questions: 1) where does it come from and 2) what does it say? It's probably the mirror image of a label somewhere on the camera. Upside down, it says "!R" or "IR" Assuming all letters are capital, the letter before the I is probably an N, the one behind the R probably an U — IRU.

“There are several ways in which a planet can disturb the internal motions of matter in its host star, thereby rearrange the distribution of the various chemical elements and possibly cause the destruction of lithium. It is now up to the theoreticians to figure out which one is the most likely to happen,” http://www.eso.org/public/outreach/press-rel/pr-2009/pr-42-09.html FYI, a lack of lithium in a star may indicate the presence of exoplanets. This could be a short cut for exoplanet hunters.

Evidence !!! Show me all the Evidence !!! , that space goes on forever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ever and ev…

Is this a plausible scenario (?) — please comment Prof. Richard A. Muller has shown that the Lunar cratering rate actually increased, beginning about 400 Mya*: By extension, the cratering rates on the Earth, and even across the Inner Solar System, likely increased too, from ~400 Mya. * PBS Exploring Space — The Quest for Life (DVD) A.J. Meadows (The Future of the Universe, pp. 118-125) says that, as our Sun orbits around the Galaxy, it travels into, thru, and out of, our Galaxy's Spiral Arms; and, that these can cause close encounters with Star Forming Regions, on ~200-500 Myr time scales: The Sun is currently positioned near the edge of a …

Is this a physically plausible scenario (??) — please comment In the Lunar geologic [Lono-logic??] timescale, the "Early Imbrian Epoch" (3850 - 3800 million years ago*) is associated with the Late Heavy Bombardment, and the resulting huge impact basins, which would later fill w/ lava to form the Lunar Mare, during the ensuing Late Imbrian Epoch (3800 - 3200 million years ago). This happened when "the mantle below the lunar basins partially melted and filled them with basalt"**. * Early Imbrian - Wikipedia, the free encyclopedia ** Late Imbrian - Wikipedia, the free encyclopedia Now, it is well-known that the Moon first formed roughly 15 times closer to Earth th…

Hi Everyone, I'm wondering how many arcseconds the Sun "travels" in one Tropical Year. I think it travels 1296000 in one day. Mark Merged post follows: Consecutive posts mergedSo, this is from the reference point of someone standing on the solid Earth in one spot all year. We could say that the sun starts at 90 degrees, goes down and up and back to 90 degrees(of course as the seasons change, the angle changes but that doesn't effect the calculation of angle travelled, and it does this 365 times, eventually coming back to the same position in the sky. 360 degrees times 365 days. Here are my calculations: One year: 131400 degrees, which is …

According to Stephen Eales' Planets & Planetary Systems, pp. 73-75, earthquake longitudinal Compression Waves (P-Waves) travel w/ velocity: [math]v_{p}^{2} = \frac{\left( K + \frac{4 \; \mu}{3} \right)}{\rho}[/math] while transverse Shear Waves (S-Waves) travel w/ velocity: [math]v_{p}^{2} = \frac{\mu}{\rho}[/math] where "K is the bulk modulus of the rock, [math]\mu[/math] is its shear modulus, and [math]\rho[/math] is its density". His discussions seemingly suggest, that the bulk & shear moduli of rock remain roughly constant, across the range of conditions encountered in planetary interiors. Since earthquake wave velocities are inversely proport…