# All Questions

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### Why is the Boomerang Nebula colder than the CMB?

An earlier answer on temperature mentioned that the temp of the CMB is 2.4K and the temp of the Boomerang nebula as 1K. How did the nebula cool faster than the CMB?
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### If the 24 microarcsec parallax precision of the Gaia spacecraft is a 1-sigma value, what is the smallest parallax…?

If the 24 microarcsec parallax precision of the Gaia spacecraft is a 1-sigma value, what is the smallest parallax that could be measured to a 3-sigma confidence? What distance, in kiloparsecs, does ...
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### Is there any practical use for astronomy?

Although astronomy is very cool and the things we are learning are awesome, is there really any practical use to knowing the things we know about the universe? Do other fields of science draw from ...
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### Is it certain that dark matter consists of particles? (And not just curved space)

The main idea about dark matter today seems to be supersymmetry. That there exists a set of yet undiscovered fundamental particles which (in a mathematically most convenient way) mirror the particles ...
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### Orbital Elements Mars near June 2014

do you know any website in which I could obtain orbital elements of planets at some date? For instance, I'm now needing the orbital elements of Mars around June, 2014. Thanks!
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### Is there any astronomical phenomena that could emit strong radio waves with multiples of a discrete frequency?

In the New Scientist article Is this ET? Mystery of strange radio bursts from space, it is reported that several times since 2001, astronomers have detected fast radio bursts that seem to have a ...
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### Why do objects burn when they enter earth's atmosphere?

Why do all objects burn when they enter our atmosphere? is this because of our atmosphere composition? and does this happen on other planets as well?
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### Is it true that chaotic inflation is the most popular inflationary model nowadays?

Old inflation was ruled out, and I think that Linde's New inflation has its problems. There's an astonishing number of inflationary models out there (more than 100?) and they're all too technical for ...
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### What would happen if a body were to fall into a neutron star?

We know neutron stars as a very massive object with extremely strong gravitational forces that composes mostly of neutrons. I couldn't help but wonder, what would happen if an object fell into a ...
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### Collision of asteroid and gaseous planet - what would happen

What happens when asteroids (or other small bodies) "collide" with a gas planet? In my head it would either go through it or just stay "inside" it due to the strong gravity. I tend to believe in the ...
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### Why is MRI important in disc formation?

I understand the principle of the magneto-rotational instability, but why is it so important for disc formation? Does it cause large scale turbulence that helps the evacuation of angular momentum? If ...
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### SDSS: Inclination of a Field?

I am working with the Sloan Digital Sky Survey CasJob service. I am trying to determine the ellipticity of a galaxy using the stokes parameters $U$ and $Q$ from which I can deduce $e$ and $\phi$. But ...
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### How do we find the exact temperature of a star?

This is a very basic question, but I am a little confused. As far as I know, the temperature of a star is analyzed based on the color of the light it emits. So, if a star is moving away from us, then ...
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### Why aren't brown dwarfs the dark matter?

There seems to be not enough matter to account for the fact that the speed of some stars located far from the Galaxy center is almost the same speed as those stars found nearer to the center of the ...
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### Is there a publicly available Gliese Star List

Is there a publicly available list of the Gliese catalogue of nearby stars with their constellations? or a Gliese to Hipparcos List ?
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### Calculate Distance To Stars

I was just watching a lecture from Carl Sagan. He talked about figuring out the distance to the stars; it got me interested in learning more about the subject. As far as I know, the Inverse square ...
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### How much mass does an object in space need to keep a human on its surface?

Assume there were a roughly spherical object in space like a meteorite or a comet. If I weighed 80kg on Earth, how much mass would be required for an object in space so that I could stay on its ...
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### How do we know the universe's expansion is speeding up?

Please forgive my ignorance, I am not an astronomer, just an interested layman. The further away a galaxy is from us, the faster it is moving away from us. But the galaxies we see exist in the ...
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### What happens when star spins too fast?

Some stars such as a neutron star can spin very fast around 600 times a second, wouldn't the star be ripped apart? Although the gravitational pull is very strong but gravity is the weakest of all ...
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### Does the mass of the universe ever change?

First do we have anyway to even estimate the mass of the entire universe? And then is there any data that shows mass being gained or lost? Would we ever know if someone was playing with the til.
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### What could be the utmost lowest temperature in the universe/multiverse?

What could be the utmost lowest temperature in the universe/multiverse?
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### Can we observe what objects exist at the L3 positiion of planets of our solar system?

From what I understand Earth's L3 is obscured by the Sun, so is that true for our viewpoint of the other planets? Or, are there times when other planets are on the other side of the Sun from Earth and ...
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### Total solar eclipse, supermoon, and spring equinox all happening at the same time: anything special about this?

Today (March 20, 2015) is seeing a rare combination of the spring equinox, a total solar eclipse, and a supermoon. I am wondering if there is anything special astronomically about all three of these ...
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### Binary stars system ultimate fate

I read an article mentioning that when two stars orbiting each other they'll produce gravitational waves that can carry away energy into space. These phenomenon increases the speed of the two orbiting ...
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### Naming of the planets of the solar system

Planets of the solar system have been named with Roman mythology gods names. I have a few questions on my mind concerning that subject for a while: Who decided to name them like this? When did the ...
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### death of a red dwarf star / minimum mass needed for a white dwarf?

OK, first, I know there's a variety of sizes and types of red dwarf stars and the universe is too young for any of them to have reached the end of their main sequence phase yet, so it's all ...
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### Can ground based telescopes use a starshade in space?

1) Could a starshade in orbit be used by ground based telescopes? If so, what kind of orbit should it have? 2) Could the same starshade be used by two different space telescopes, or does the ...
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### Why doesn't Earth's axis change during the year?

My understanding is that the Earth's axis points in the same direction in space during its entire orbit around the sun. And this is what causes our seasons. My question is why doesn't the axis follow ...
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### infrared telescopes, magnitude and observations

Currently 22-23mag could be the limit to make a spectrum for ground based 10m class telescopes, 21-22may may be easy for them. 4m class telescopes could handle 20mag? I am not sure. 2m could be ...
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### how to tell an optical spectrum is featureless or just with a low S/N?

A featureless spectrum and a spectrum low S/N are very similar. Is there a way to tell them?
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### Is it possible to use the stars to determine the passage of time?

I'm writing a science fiction short story which involves a group of people being in suspended animation for a very long period of time, on the order of thousands of years. My question is, would an ...
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### Is the Oort Cloud actually opaque, or is the “cloud” used euphemistically because minor planets inside of it are too dim to be seen?

I did read several of the Oort Cloud questions/answers which I found very helpful and instructive, but this question still persists for me: Is the Oort Cloud actually opaque, or is the "cloud" used ...
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### Why can't we observe the Oort cloud with a telescope?

The Oort cloud is a hypothetical structure based on our observation of long-period comets. There are currently proposals to design probes to confirm the existence of the Oort cloud. Now, sending a ...
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### Is it possible that some stars are already black holes yet we see light emitted from before becoming a black hole?

For stars we see that are burning fuel at a fast rate, that are very bright, (or any star for that matter sufficiently far away from us) could it be that they are already black holes (the sufficiently ...
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### Leaving the Milky Way

If we had a hypothetical spacecraft, would it be possible to exit our galaxy, wait for some time and enter back into another section? Will this method be more efficient that a more traditional flight ...
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### What is the minimum size of a ball of gas to become a star?

I know there are two criteria to meet in order for nuclear fusion to occurs. High temperature (many times temperature at Sun's core) High pressure (protons are very close to each other) [Goal] ...
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### Why are distant objects observed in the near infrared?

I was reading an article that explains why JWST is a successor to Hubble and not a replacement for Hubble. They explained that Hubble's science pushed astronomers to look at longer wavelength. And ...
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### The Existence of Natural Satellites in Geostationary Orbits

While browsing through Physics SE, I noticed a question about satellites in geostationary orbit (unrelated to the one I'm asking here), and for a moment I interpreted it as referring to natural ...
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### Can our Sun become a black hole

Does every star become a black hole? Is there any probability that our sun can become a black hole? If yes then is it on its way to become a black hole? what is the current state of sun as per the ...
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### Around what apparent magnitude can the naked eye observe an object during full moon

For a very rough guideline using healthy/corrected eyes adjusted to the dark, around how bright should an object be to expect it to be visible?
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The further away we see, the older states of the world we observe. And the volume of the part of space which is observable, increases by the square of the distance to it. So there should basically be ...
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### BIG CRUNCH Theory

Someday before i read about a article which explained about a phenomenon called BIG CRUNCH, according to it the way Big Bang happened because of which the remains moved away from one another forming ...
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### Why did Earth need material from comets to assemble the raw materials for life?

It's often speculated that matter from comets played a crucial role in the development of life on Earth. For example, Maps of Time says, Many of the ingredients of the early atmosphere (including ...
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### are all the planet in the same plane? [duplicate]

are all the planet in solar system the same plane in the space or not ? if yes is there any especial reason ? and if no how do they orbits then ? as far as i know they are in the same plane , but is ...
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### Where is Mars in the night sky

I live around Houston, Texas and I'm taking advantage of Earth hour to look at the stars. I've found two objects that I think might be Mars. Both of them are in roughly the same plane as Venus and ...
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Stars can easily fuse atoms to give of heat and radiation. But at Wikipedia it said that only sub-iron atoms give of energy when fused and take energy when split, and post-iron atoms is the exact ...
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### Is there a threshold on distance/size for a tidal locking?

I know that some systems tend to tidal locking (such as earth-moon), which occurs basically because the difference in the gravitational pull on one side is significantly different from the pull on the ...
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### Proof that Parallel Universes exist

Today I heard on the radio that the Super Collider has discovered mini black holes. They said that this discovery is proof of the existence of Parallel Universes and that the "Big Bang" never ...