Astronomy and Cosmology

Hi, I got this question in my head....... Of course it seems quite true that there is no sound in space. But there might be exceptions. So is our universe completely silent??

Ok, I'm trying to get a grasp on the n-body problem as I want an earth-like planet with two large moons of roughly the same size. One scenario is same sized moon twice as far out or a closer moon (Io-type) half the distance between Earth and Luna. Basically, they would NOT be sharing an orbit or Lagrange Point. From what I gather, the Earth isn't massive enough to hold both bodies without them gravitationally pushing one another about too much, at least over medium to long term. I'd like to have this be relatively stable for billions of years. No crashing into the Earth of being expelled. Is this possible? Everything I hear says no, that the system would become u…

Howdy, when I look at the night sky and between the stars I observe a black back ground , what am I observing? Do I observe a ''roof'' with ''spotlights'' in, an edge of space? Or do I observe just the lack of bodies reflecting light?

Question from an amateur writer: Most planets around Red Dwarf Stars, at least close in, are tidally locked due to proximity. Would this change for planets orbiting a pair of very Close Binary Red Dwarf stars (probably a two or three day mutual orbit)? Since the planet is being dragged by two different suns, often from two different locations when the planet is orbiting from the "side" and can see the suns from two different angles, would the planet be tidally locked is some way? Maybe locked to the common barycenter between the stars? Or would this dual source of gravity allow for the planet to retain its rotation, perhaps even encouraging it? Also, rel…

How all species developed out of a Big Bang . You disclaim primordial soup so what then ? .

Why gravitational waves are so exciting for physicists and their supposed detection is a great scientific sensation? The occurrence of gravitational waves after all clearly stems from classical physics. Such waves are formed for example by any system of two large objects (masses) rotating around each other. The problem of detection of gravitational waves on Earth lies in the fact that the amplitude of these waves decreases rapidly as it moves away from the rotating system and it becomes practically unmeasurable already within a few hundred million km (<0.001 ly) of this system ( eg. with mass of two suns) . Detected so far such binary systems are distant from Earth…

Hello, I would like to known if this is exact : if Cosmological constant = [LaTex]\Lambda = 1,111*10^{-52}* m^{-2}[/LaTex] we have with this document, the last values of Plank mission and codata values : Vacuum energy density of cosmological constant = [LaTex]5,354**10^{-10} Joules*m^{-3}[/LaTex] Planck force = [LaTex]F_p = \frac{c^4}{G}[/LaTex] [LaTex]\frac{F_p*\Lambda}{8*\pi} =5,354**10^{-10} Joules*m^{-3}[/LaTex]=Vacuum energy density of cosmological constant. is the relationship exact and new ? Thank you in advance

I know very little about astronomy and it occurred to me that I've only ever heard of plantes orbiting stars, but I can't think of a reason why that would always be so, are there planets that are not orbiting stars?

So according to "everything in this universe has something which is same in magnitude but opposite to its nature" Blackholes have whiteholes. But there is no scientific evidence to prove such a thing. Now if we say that blackholes have an immense amount of gravity, then whiteholes should have an immense amount of antigravity(?)(lets repel everything and everyone!!). Is this why none have been found? PS Quick definition of a Whitehole: Your kid in your car after a hearty meal in the downtown restaurant.

I thought the Solar System is the Sun's system, but I see a lot of publications using solar system as a generic term for a star system. Which is it?

Under influence of gravity the Hydrogen molecules are attracted to each other. There is deuterium fusion???(How is deuterium formed in the first place???) The atom with near light velocity in the dense nucleus is unthinkable. There has to be some other explanation for fusion trigger. The trigger must be lightning of very high voltage that must be producing very high temperatures and highly kinetic particles, which may be culminating in a fusion reaction.

hello can somebody give the exact value of vaccum catastroph with 1 decimal and the calculation please ? thank you in advance. stéphane

I seem to strongly remember when a Russian spacecraft was in deep trouble and a US spacecraft came right next to it and a US astronaut came out and fixed something vital on the Russian ship. I also seem to remember that the Russian craft was known to be in troube and a US craft was sent up specifically to rescue it, among other things. It was treated with great hoopla at the time, but I seem to be unable to find exactly when it happened on internet search engines. I seem to remember the Russian craft as being old and antiquated, so maybe it was Mir. Any help would be appreciated.

I’m trying to grasp, in a non-technical way, the ideas underlying the theory of eternal inflation. If I post some of my thoughts, I would really welcome comments/criticism as I go. In order to have a situation in which this eternal inflation can operate, we must have an infinite vacuum, with a measurable vacuum energy. Quantum mechanics provides us with this, because it forbids us from having the classical vacuum, which can be identified as absolutely nothing. Absolute nothing provides absolute information about its state, and the uncertainty principle does not give us that luxury. There has to be the possibility that the vacuum is something. In fact, to the …

I think it is mostly to do with the "romantic" idea that Mars is a lot more hospitable than the moon and that we could eventually Terra-form Mars into a Second Earth, where it would be a wonderful place to live. Mars has long had a special place in our imaginations. I don't think that most people realize that Mars is almost as inhospitable as the Moon, i.e. that the atmosphere is very thin, that on the surface of Mars we would have to wear pressurized spacesuits, that we would have to live in pressurized habitats, that the surface is bombarded by solar and cosmic radiation, and that most of the planet is below freezing all of the time. Mars being so much farther …

Hi everyone ! I want to participate to a nasa competition so i have to make a video ecplaining a science topic ! I prepared one about meteors but i'm not sure if it's good enough ... can any one tell if it's an interesting science topic ! If not .. could u pleasr suggest me one in physics and astronomy ! And i'm wondering were can i find some scientific simulation and animation for my video ! Thanks ! i would be really grateful if you could help me !! ^^

Can someone explain how Comets come to be and why they don't get destroyed sooner also how they stay in the same orbit, TA .. Are they parts of destroyed planets?????

Today is "How the Universe Works" on The Science Channel for the next 8 hours. Anyone else follow the series? Today I am watching an episode called "Megaflares" and I believe I caught an error. They said that every day we see about one gamma ray burst, or about 350 per year. They said that every gamma ray burst is the birth of a black hole. Do some gamma ray bursts mean the birth of a neutron star? I heard someone say that about one black hole is born every day in the observable universe. But that must be wrong, there must be many more born each day because for every gamma ray burst WE CAN SEE means many more are happening that are NOT POINTED DIRECTLY AT US. …

Links removed by mod Basic introduction to classical mechanics, general and special relativity, quantum engineering; But also... The philosophy of quantum mechanics for the more professional physicist. For the expert, and the average person.

Hello I am working on an orbit trajectory plot tool with my friend from the US. I have some question to ask all of you about this question. In our trajectory plot, we would like to fix Moon as the center of our orbit plot. Then, from our perspective (the moon), what would the Earth's orbit be or look like? From the moon's perspective, would the Earth seems like orbiting the Moon? If this is the case, how long does it take for Earth to "orbit" the Moon? The same period as lunar's orbit, i.e. 27 days? Thanks for answering. Nicholas.

Is it safe to assume that since distant galaxies recede from us at a rate greater than c that they eventually leave the gravity well of our galaxy? If so, does this imply that Dark Energy will have a greater impact on recession rates over time as gravity wells are no longer an influence on distant galaxies; that recession rates increase over time and not just over distance?

Simple question, hoping for a simple answer. Are all of the planets and such in the Sun's gravity well? Is Luna in Earth's gravity well?

Well, I know systems are of two types : Closed,isolated and open. What type of system is this Universe? and can you provide arguments to justify your answer?. I studied these systems related to thermodynamics.

Exactly how did astronomers before Newton come up with all of the values for the various characteristics of the solar system bodies, i.e. orbital parameters, mass of the bodies, etc, so that they could predict the motions of the planets and their moons back then? There wasn't much that they could directly measure! Exactly how did Newton come up with his Laws of Motion and his Law of Universal Gravitation? How did he come up with a value for the gravitational constant "G" in F=GMm/r2, r2 is actually r squared? For the surface of the Earth, GMm/r2 = mg, where "g" is the acceleration due to gravity on the surface of the Earth, M as the mass of the Earth and r is the r…

Curious because I recently read about it.