# All Questions

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### What are Flamsteed numbers?

Can you tell me about Flamsteed numbers? I just know that it is a specific number used for identification of stars. But what is the theory behind it? In what way is the number given to stars?
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### Collimator for Dobsonian, same as Newtonian?

I have been looking on line for Collimator for my Meade Dobsonian. The only Collimators I can find are made for Newtonian Lenses. It's a 8" mirror with a 1.25" lens. Will this work for my telescope?
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### Why do the rings around the Gas Giants get their 'ring' shape?

In our Solar System, all the gas giants have ring systems. However, why do these rings form rings and not a cloud of debris around the planet?
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### Is it possible for a person to not see the new moon at different places on earth?

It is known that theoretically we see the same moon phase everywhere on the earth, but practically I see that people are unable to observe the 0.8% waxing crescent at different places on earth. This ...
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### Birth and Evolution of Millisecond Pulsars

How are millisecond pulsars formed, and what is the evolutionary track of a millisecond pulsar?
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### Observational Evidence for the Existence of Black Holes

What is the direct observational evidence that black holes exist? I have read that black holes have been detected through X-ray emission. What is some other observational evidence for black holes?
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### how does Kepler stop exposure after a 5 minuate or 30 minute cadence time?

There are two kinds of cadence time for Kepler, 5 minutes and 30 minutes. I just know there is no shutter and the CCDs of Kepler can be locked after exposure. handbook But how to realize that? ...
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### Gallery of 'actual images' from space?

where can a gallery of actual unaltered photographic images taken in (or of) space be found? Specifically ones that are untouched, not colorized (not necessarily black and white), and taken by natural ...
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### What would the effects be on Earth if Jupiter was turned into a star?

In Clarke's book 2010, the monolith and its brethren turned Jupiter into the small star nicknamed Lucifer. Ignoring the reality that we won't have any magical ...
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### How did the Hulse-Taylor Pulsar Provide Confirming Evidence of General Relativity?

What measurements and observations of the Hulse-Taylor Pulsar agreed precisely with the predictions of general relativity, and how did these measurements support the theory?
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### What is CMB radiation doing to the universe?

It is said that due to CMB radiation our universe has been expanding? Firstly what lead the universe to expand? What do scientists mean by dark energy? Will energy convert into matter?
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### Is the argument of perihelion random?

I am currently designing star and planet systems in the RPG framework GURPS. This game system has a very elaborate set of rules to set up a star system, complete with planets and the like. However, ...
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### Astronomy questions I wondered for hours [closed]

I read a question posted by a community member in my community that shocked me, I think it contains some pretty cool astronomy questions that I cant wait for you scientists to answer. I am asking this ...
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### Date and time system on moons

Supposedly, if humans were to establish a colony on one of the moons of a planet (such as gas giants in our own solar system), how could we possibly design date and time system? On Earth, we define ...
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### Why does this twilight sky flat field have a grid of dark pixels?

The image below is a small region of a twilight flat field. A grid of darker pixels with 728x36 cell dimensions can be seen. The camera used was the SBIG STL-6303 according to the FIT headers, which ...
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### Can there be an infinity of humans in the Universe? [closed]

I was reading this question about if the number of stars can or cannot be infinite. The answer to this question is: ...
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### How do you model galactic noise based on raw signal data?

I am collecting signal data in the 50 MHz to 300MHz range. The data is stored as a function of time and frequency. What methods can I use to determine what noise is caused by the galaxy once I ...
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### Visibility of Apollo 11 module

I wasn't around when man landed on the moon in 1969. When I see the moon, I always wonder, were people able to see the rocket? Yesterday, I looked at the moon in daylight and wondered again. My ...
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### Determining planetary positions on the celestial sphere by Right Ascension and Declination

How would one go about determining the position of the different planets in our solar system with respect to the celestial sphere based on the following data set? Is there a practical way to calculate ...
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### Distance between each dish in an array telescope configuration

In an array telescope configuration, like VLA and ATA, what dictates the distance between each dish?
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### Can there be an infinity of stars in the Universe?

I have a mind puzzle. Can there be an infinity of stars in the Universe ? I have 2 opposed reasonings, yet I don’t find any flaw in them. Can you help me here ? Answer A : No, the number of stars ...
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### With gravitational lensing, is it possible to mathematically compute the correct image of the galaxy that is being distorted?

There's been another report of gravitational lensing in the news. Wikipedia has a good image of an example of gravitational lensing taken by the Hubble Space Telescope. This brings me to wonder ...
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### How can the Advanced Composition Explorer (ACE) warn of incoming solar storms?

How can the Advanced Composition Explorer (ACE) warn of incoming solar storms when is is invested with radiation? Discovery.com article Solar Storm Warning Satellite on Last Legs states that: ...
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### How do telescopes “zoom” and change angle of view?

Images from the Hubble Space Telescope have widely different angles of view. Is this only the result of composing multiple images, or can the telescope itself change its "zooming" optically, ...
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### Aren't there more naked-eye-visible stars in the Milky Way plane?

Most stars which are visible to the naked eye are within 1,000 light years. The Sun is inside the Orion arm which has a diameter of about 3,500 light years. Thus, all stars (with very few exceptions) ...
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### Inclination of planets

Why do the planets have roughly the same inclination with respect to Earth? Looking at the inclinations, which I got from http://www.astronomynotes.com/tables/tablesb.htm , we see that Mercury has ...
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### Is the Hubble Ultra-Deep Field image representative of the entire sky?

The Hubble ultra-deep field image is a photograph of an area of sky equivalent to a 1mm x 1mm piece of paper held a metre away from the eye (one thirteen millionth of the entire sky). It contains an ...
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### Could a habitable satellite of a gas giant have a stable subsatellite?

I have set a science fiction story on a moon, orbiting a gas giant (which orbits its star at approximately the same orbit as the Earth around the Sun), and given this moon its own satellites. The ...
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### Landing on an “earth-like” planet (practical application)

This may not belong here in astronomy and my apologies if that's the case. The hypothetical: We find, and are able to travel to (in a reasonably short amount of time), a planet that is for all intents ...
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### Where does the Milky Way end?

I was reading this article and it says the following: Researchers measured the mass of the Milky Way and found that our galaxy is approximately half the weight of a neighbouring galaxy known as ...
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### Why can't we determine the center of the universe [duplicate]

I find this baffling. If we can observe objects moving away from us and each other, than it stands to reason that we can track their paths (relative to each other and ourselves) backward to find a ...
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### how did James Bradley discover light aberration?

I do not understand his timing method. James The magnitude of the aberration could be v/c? The speed of earth is about ...
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### seasons elongating and shortening

I have heard of years with longer summers and winters and shorter springs and falls and vice versa because of a change in the earths axis. Is this from the procession that causes the season switch ...
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### How do we determine something is “x” light years away? [duplicate]

I always read/hear "This galaxy is X thousand light years away" or some similar statement (for example see this table). Please excuse the naivety of question. How do we determine that some ...
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### How did the reionization epoch make the universe “transparent”?

I've been reading about the reionization epoch of the universe, and it isn't entirely clear to me. As I understand it, very shortly after the big bang the universe was ionized, with the electrons ...
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### Perception of an objects history passing as an observer moves toward it

If a star is 20 light-years away and I look at it through a telescope, what I'm observing is what the star was doing 20 years ago yes? So, if I fix my sight on the star and move toward it (for ...
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### Does the universe have an edge?

I've heard the universe is just an empty cavity. Does the universe have any edge or stop or is it just an infinite empty cavity?
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### Compute Planet's Apparent Visual Magnitude

In a hypothetical solar system there exist: a sun of radius $r_s$ and absolute visual magnitude $V$ the Earth, with radius $r_e$ and distance from the sun of $1\,AU$ another planet, wit radius ...
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### What is this graph showing?

This is from the NED What do these three titles mean? log fb (Jy) MRK 1014 Log v (HZ) Why is there LINE,LINE,...
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### What did I see streaking across the sky last night?

I was enjoying a casual naked eye view of the summer sky last night around midnight in a new jersey beach town. The sky was pretty clear for around here.The Milkyway was just visible and there was no ...
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### Are these facts about moon true?

I don't have much knowledge of Astronomy but today I was googling randomly and found an article, according to which: The moon is of the wrong size for its current orbit. The moon rings like a ...
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### Would an ultra bright moon indicate that the world is ending?

There is a sci-fi television episode that shows a man looking out the window into the night sky. There up in the sky is the moon, and it's extraordinarily bright. The man spends the rest of the night ...
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### How massive does a planet need to be to create gravitational lensing?

Is it ever possible for starlight to be distorted in a noticeable way from something as small as a planet? I'm guessing that the chances of this working are better on a dense terrestrial planet than ...
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### Can we hear something on Venus, Mars and Titan?

Mars, Venus and Titan have an atmosphere and we can theoretically step on them (and die quickly). So, as an example, let's say we can survive on these objects without a space suit. I say: “Hi” on any ...
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### What known comets are binary?

Many asteroids are today known to be binary, to have "moons". But what comets are known to be binary? Or what fraction of them are theoretically thought to be binary? And if possible, then separate ...
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### How does a gravity slingshot actually work?

From what I know of elliptical orbits, an object speeds up near the periapsis and slows down at the apoapsis, much like we learned in high school physics how a sphere would roll down and back up a ...
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### Can the asteroid belt be seen from Jupiter?

Suppose that someone lives in the neighborhood of Jupiter. He may live in a space station around Jupiter, or in any ot it's moons (I believe that it doesn't matter for this question). If this person ...
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### What's an order-of-magnitude main sequence star look like?

I'm looking for a very rough, order-of-magnitude approach to the main sequence. What I mean is, I have a spherically-symmetric hydrogen distribution. I'm looking to get a rough approximation for ...