Astronomy and Cosmology

Apparent Magnitude (m): [math]m = M_{\odot} - \frac{5}{2} log_{10} \left( \frac{F}{F_{\odot, 10pc}} \right)[/math] [math]M_{\odot} = 4.76[/math] [math]F_{\odot, 10pc} = \frac{L_{\odot}}{4 \pi \; 10pc^{2}}[/math] Received Flux (F), across cosmological distances: [math]F = \frac{L}{4 \pi \left( w \left( 1 + z \right) \right)^{2}}[/math] Present distance (w), equivalent to the comoving coordinate, of an observed object, at a given Redshift (z), in a Flat universe ([math]\Omega_{0} = 1[/math]): [math]w = \frac{2 \; c}{H_{0}} \left( 1 - \frac{1}{\sqrt{1+z}} \right)[/math] [math]H_{0} \approx 75 \; km \; s^{-1} \; Mpc^{-1}[/math] From thes…

Hey everyone, I'm new to this forum, but that's not the purpose of this post! I was reading the article "The Universe" (by Michael S. Turner; Scientific American, Sept. 2009), and it says "at some point it [the universe] developed a slight excess of matter--about one extra quark for every billion anti-quarks." Is there proof that there is more matter than anti-matter in the universe?

REVISED UPDATE (1) Circumstellar Disk Analogy — Magnetic Field Lines transfer Angular Momentum outwards According to Jayant V. Narlikar (From Black Clouds to Black Holes, pp. 61-64), magnetic field-lines, threading through circumstellar disks, can spin up outer disk regions, while spinning down inner disk regions: In Figure 5.9, a magnetic pole at A will be forced by the magnetic field in the cloud to move to B along the line of force. Now, these lines of force have a tendency to stick on to cloud particles all the time. So, as A & B rotate about a common axis, the line of force moves w/ them. But, since A & B do not rotate at the same rate, w/ A r…

Planetary Mass Growth Rates, in Proto-Planetary Disks, are calculated to be (C.A.Scharf. Extra-Solar Planets & Astrobiology, pg. 89): [math]\frac{dM}{dt} = \pi \; R^{2} \left(1 + \left( \frac{v_{esc}}{v_{rel}} \right)^{2} \right) \; \rho_{disk} \; v[/math] And (ibid., pg. 102): [math]\rho_{disk} \; v \approx \sigma_{disk} \; \omega[/math] where: [math]\sigma_{disk} \approx 1700 \; \left( \frac{D}{1 AU} \right)^{3/2} \; g \; cm^{-2}[/math] We assume that the average Relative Impact Velocity (vrel) is equal to the Keplerian Disk Velocity (v)*. * This can be verified, by assuming that all potential Impactors possess, at the beginning of their plane…

In June 2009 the IOP (inst. of phys.) published an essay by Smolin in their wide-audience magazine Physics World. The essay called The Unique Universe brings out some new ideas about the universe. It seems to have gotten a good reception. Anyway something has driven the sales of Smolin's book way up. I just checked and the salesrank was 852 compared with Brian Greene's books 2539 and 3817. The five most popular stringy books had average salesrank 6936. So Smolin was doing 8 times better. That was at 11 PM pacific time on 2 July. There haven't been any radio or TV appearances that I know of, all he has done that could possibly boost sales is put this piece in Ph…

Science seems to be saying that God must be made up of "somethings" that have a unit size of less than one "Planck length". Why? Because in physics, the Planck length, is a unit of length, equal to 1.616252(81)×10−35 meters and is the smallest distance or size about which anything can be known. Move this idea into Big Bang theory. Following scientific reasoning to date, "Pure Vacuum" or "absolutely nothing" does not exist and specifically did not exist in the Universe before or at the exact instant of the Big Bang. However science is concluding that something existed concurrently with the instant of the Big Bang...but just not Pure Vacuum and, according to physics, not …

Original Article : http://sciencerealm.net/index.php?tid=41 Neptune, the 8th planet in our solar system was first seen by the famous Galileo Galilei on December 1612. Galileo wasn't confirm with his discovery because of the limited capability of the telescope at his time. He noted down the shining spot he observed next to Jupiter as a "fixed" star, rather than a planet revolving the Sun. More than 2 centuries had passed, with the help of Newton's Gravitational Law or Law of Motion, scientist and astronomers begin their search of fantasies in heavenly space. From the observation of Uranus, astronomer noticed that there's a perturbation on its orbit. From the…

Hi, Anyone see this??? We had company and I only caught glimpses... they showed a spiral of gas from some binary system where one star was a super giant due to go nova soon (soon being relative). They talked about GRB (Gamma Ray Bursts) that might take place when it went super nova and said the stars axis was pointing at us and showed how the GRB might hit Earth. Did anyone see this... know what star they were talking about... know how far away? Yeah... well, in any event (pun intended)... just how big of a diameter would this GRB beam have? They show a beam a little less then the diameter of the Earth hitting Earth. I can't believe that a beam that size w…

The moon is drifting away slowly. What about the Earth from our sun -- or towards? If the Earth drifts from the sun a good distance, I'm thinking it can potentially avoid the fate of an enlarged sun down the road.

So how many dippers is in our sky ?. WHAT only one dipper ?????. Wrong !!! again. There is two dippers in our sky. One is the Big Dipper where the end points to our Polar Star that never moves only up and down somewhat. The big dipper is in our northern hemisphere but in observing our sky I see the ( Lesser Dipper ). And that is in our low southern sky. So in navigating our ocean in true east and west direction I can navigate between the big dipper and the Lesser dipper when plying the ocean. I am a retired Blue Diamond Almond grower all my life. I am calling the southern Lesser dipper. ( THE FARMERS DIPPER ) I think some astronomer should wri…

I don't remember what magazine, perhaps Discover (a while back), the article said NASA planned to have giant telescopes arranged in a system where each is many kilometers away from the others, with their lens perfectly aligned to create a fantastically large magnification (because of the distance apart). The other thing I remember is a scientist's claim that if aliens did exist on a planet, with this you'd be able to see the white of their eyes. Anyone familiar with the article, or the concept, plan, whatever?

Does not make sence. This orbit & gravity is a little bit strange. I don't even believe the universe is expanding. Pictures is taken of distant galaxys over many days, where the blur from expanding universe? Gafferuk, Bristol.

Really cool video of the farthest images from Hubble, with distances calculated to show in moving 3D. Some decent coverage of expansion I think:

Ha I'm wondering what is going on. Jupiter was hit not to long ago. Now this: http://blogs.discovermagazine.com/badastronomy/2009/08/09/like-the-fist-of-an-angry-god/

if universe was a pt at the time of bigbang what was outside that pt? what was before that time?

Is there any? What difference in 3D size exists between a tiny black hole and a super-massive one? For isn't a black hole simply a point with no dimensions regardless how massive? If they do lack physical dimensions, and consequently have no size difference, is the radius of their event horizon the only difference in size?

Is WMAP and COBE a map of the universe? It look like a globe but with hotspots? I have read that it is a map of our known universe. Is that true?

Okay, so I recently started looking at a book on astronomy. The name of the book is Astronomy, and the author is Ian Ridpath. In the part of this book that gives information about the big bang theory, it states that a hundred billionth of a yoctosecond after the beginning of time, the temperature of the universe was 1,800 trillion trillion degrees. What I'm wondering is - how do astronomers know this?

I had always assumed that the galaxy's "arms" were more-or-less stable structures. Thus, I assumed that the solar system would more-or-less "always" be located at a given spot in one of the arms, and would spin around galactic center along with the rest of the arm. Lately, I have heard several references to the idea that the solar system actually travels through the arms. I am confused as to why that would be the case. Cursory thinking suggests to me that the same gravitic circumstances that create the arms would be the deciding factor. But I am apparently wrong, So, can anyone please explain a) whether the solar system does actually move through the arms, and b)…

Are universe expand all the time? This is a question i have been looking an answer to for many months. Maybe you guys here can help me?=) And IF the universe is expanding, how can it do that? And what does it expand in? A greater space?

Hello, I've been a member of this forum for a while. I've just been lurking and reading mostly. Never really had anything to post before, as there are many very intelligent people in here. I'm also a member of other astronomy/science forums and I thought I would post this in here as it has gotten lots of post in the other forums. I'm starting to think that it's not fair to only be allowed one question though? Even though getting some of the most fundamental questions answered would lead to other questions being answered. It would also lead to more unanswered questions. If you could have one question answered about the mysteries of the Universe what would it be?

Hi People, I know that astronomy has estimated that they have picked of light from the very early universe, and some quasars are said to be receding at 6.0 c or greater than the speed of light relative to us on earth. I can accept that as a truth, but what I cant rap my brain around, how the heck do we on earth see objects from the beginning of time?. When we target our telescopes at these unimaginably distant objects, they might have already ceased to exist. Some Quasars are extremely energetic primordial galaxies living and dying in less than a billion years or so. Our earth is about 5 billion years old and was born some 5 billion years after the cr…

http://www.astro.princeton.edu/universe/all200.gif If you get a little strip of dots down the left side of the page, put your cursor down near the bottom of the strip and you should get a little "expand to regular size" icon. Click on that, and see a fantastic compilation of all the observations made and work done to date. (I would particularly like to talk about the lines at z=0.76 and z=1.69.) Regards, TAR

Systems have been found with Jupiter-mass planets in the habitable (liquid water) zone. Suppose a planet massing several Jupiters had one or more moons massiver than the Jovian ones: Io, Europa, Ganymede etc., in our system. Would Jupiter moons be habitable if they were closer in, and warmer? And more massive as well? It's an interesting possibility. So here is an interesting variation or extension of the exoplanet search: We already know how to detect exoplanets (by star-wobble and transit methods) so how about searching for moons of exoplanets? A method has been worked out for detecting exomoons by precise transit timing. If any are found then if som…

The answer is NEOs! Men have been to the Moon. Send robots there and to Mars. What we really need to do to win the respect of the world is develope a fool-proof defense against bolides. The other projects are very expensive, just for fun. A defense system can save the planet. Yes an extinction level event is very, very unlikely in the near future, but we don't know all the threats. Better to be safe than extinct, or living in the stone age, again.