# All Questions

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### How close would quasars have been to each other?

My understanding is that quasars are the early phase of formation of galaxies. At the time quasars were forming, the universe would have been smaller and therefore things closer to each other. About ...
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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 everything quantum entangled?

So, I am learning about quantum entanglement in my quantum course and had a thought. If the Big Bang is the creation of everything - time included, and this came from a single "source". Would it not ...
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### Has life been discovered outside of Earth?

I've just watched a movie that made me curious as to whether life has really been discovered on another world such as Europa??
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### Galactic extinction as a function of distance

I am looking at several galactic sources in the $I$, $R$ and $V$ bands and I want to calculate their absolute magnitudes. I can get the apparent magnitude and I know the distance so I just need to ...
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### What is the Northernmost Latitude of Saturn?

My wife and I were watching a TV show last night, which takes place in Salem, Massachusetts circa 1693. One character went to a particular place in the woods at a particular time to be exactly under ...
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### If an asteroid twice the size of Earth passed super close would half of the Earth be pulled towards it?

So let's say that an asteroid the twice the size of Earth passed by going relatively slow say in between the Moon and Earth. Among so many other things (and perhaps you can touch on some of the ...
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### Quantum death of stars

This comes from a comment on this question, to quote: The death of (large mass) stars is also based on quantum events with probabilities technically not 1 (and is very fast), so it is technically ...
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### Limit of hotness!

We know that there is a limit to which an object can be cooled down that is absolute zero, and getting there is also not very easy we may have to wait infinite years to get to that point. But is there ...
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### Look up current positions and velocities of solar system objects

I am working on an orbital dynamics code and, for fun, I would like to model the Sun-Earth-Moon system with my code. I can look up the masses of each object just fine, as well as average distances ...
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### Solar System formation, considering its and universe's age

It's been said that the Sun is 4.6 billion years old, and the complete Solar System is of a similar age. The class of stars to which the Sun belongs seems to be quite common. Stars of its class can ...
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### Can the theory of multiuniverse explain dark matter?

If there are many universes they must have an gravity effect on each other. Since dark matter is measured through gravity but we dont know the mass behind it, isnt it possible that it comes from ...
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### The defintion of star/planetary/solar system

In many science fiction stories, we hear the term star system that mostly refers to a star and its planets. This is often used interchangeably with the term solar system. But after some research I ...
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### Could dark matter be considered a medium?

Long ago, it was theorized that light had to travel through a medium, until the particle/wave duality of light was discovered. Then it changed to the idea that light can travel through the vacuum of ...
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### Why objects are uniquely defined by their right ascention and declination?

I've just started studiyng Astronomy. I understood how I would measure Right Ascention and Declination: for the first one I'd trace an Hour cirlce to the Celestial Equator, and then, compute the ...
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### Is there a lower limit for the altitude of orbiting objects?

As I understand it, one object can orbit another at a variety of altitudes, and the stability of the orbit is determined by (among other things) the speed of the orbiting object. Go too slowly and ...
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### Requesting book references for a non-expert person with math background or just a non-expert person

I've just finished my masters degree (to be exact previous week ^_^). And I'm completing my collection of applications of my studies. During previous year I started reading about Robotics and Coding ...
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### How can light reach us from 14 billion light years away?

One thing that I can't quite wrap my head around is how light is traveling to Earth from 14 billion light years away, aka the beginning of the universe. The way I see it, the universe itself was very ...
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### Free neutrons and stellar nucleosynthesis

Both the R-process and the S-process of stellar nucleosynthesis rely on absorbing 1 (S) or more (R) neutrons. Where do they come from? I thought there are no free neutrons in stars. (Also the ...
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### Mechanism for Brown Dwarf Fusion

I've read (at here, among other places) that during the Degenerate Era, star formation will end and the last stars will go out. But it was noted that there is still the possibility of star birth, ...
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### What type of energy is escaping from black-hole's poles?

Following this article, it is stated that: As a star drifts too close to a supermassive black hole, intense tidal stresses rip the star to shreds. As this happens, the shredded material will ...
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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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### The RA and Dec of lunar poles

The moon faces the earth with one fixed side. However there is a small vibration. So I am not sure the south and north poles of the moon is fixed. Even if they are fixed points on the moon, the pole ...
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### If Mars orbited the Earth how distant would it have to be to cause the same tides?

If it were possible to replace the Moon with Mars, how distant would it have to be to essentially create the same oceanic tides as the Moon currently does? Mars seems to be roughly 3 times the mass of ...
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### Did the Babylonians believe in the Heliocentric version?

It's mentioned that the Babylonians decreed that there were exactly 360 days in a year. This statement was based upon the utilization of 360 as a standard (based on the sexagesimal system) i.e., they ...
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### Pulsars with accreting disk in binary system

Following this line, I am wondering about the following question. Accreting pulsars in binary systems are usually thought to accrete from a prograde disk, so increasing their spin in the process. ...
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### What is the temperature of outerspace?

I want to know whether the temperature in Outer space is higher than earth's or cold.Is the temperature in outer space vary as it does on earth?
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### What exactly does outer space contain?

Does outer space contain any gases? Recently i watched a video on youtube,in which NASA installs a camera on a spacecraft.The footage shows some dust particles or some matter floating over the space ...
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### What is the orientation of planetary orbits?

I'm working on a planetary motion simulator. I've been working through the equations anomaly, eccentricity, etc. The one thing I'm curious about is if all the ellipses are oriented the exact same way ...
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### What is Event Horizon of a Black Hole? [closed]

The boundary of a black hole is said to be surrounded by event horizon - the point of no return! What is its significance in terms of general relativity?
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### regarding curvature of earth [closed]

i am having one doubt in earth's curvature.....this question may be dumb... How much we need to travel on earth to feel the curvature of earth. hypothetical case: for ex we are building a vehicle ...
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### Is radiation from neutron stars delayed by time dilation?

I understand a neutron star to be the densest stuff that can exist without becoming a black hole, the densest thing which directly gives off radiation we can detect. At the event horizon of a black ...
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### Stars in the sky

Are the stars we can see with the naked eye in the night sky only from our Milky Way galaxy or can we see stars from Andromeda? I am aware we can see other celestial objects like nebulas and the ...
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### Claim that 30-m class telescopes will have resolution far superior to Hubble: true?

This article makes the claim that the Giant Magellan Telescope (GMT, number 4 in the list) will have resolution 10 times better than that of Hubble, while the Thirty Meter Telescope (TMT, number 3 in ...
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### How long for a complete solar system cycle

Considering the solar system as a closed system, how long until all the planets pass twice by the same position relative to each other? I would say that you'd have to get the length of the year in ...
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### Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection?

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
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### What astronomical observations would give conclusive proof of alien life?

There are several ways we are coming closer to answering the question "is there life elsewhere in the universe?". One is by first understanding very well the origin life on our own planet. Another is ...
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### How long was the hyper inflation phase?

How long was the hyper inflation phase? Haw can we know that it lasted for a period of time and not more or les time?
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### Calculating 2004 BL86 position using software

Is it possible to view asteroid 2004 BL86 using Stellarium or the iOS Star Walk app?
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### How do stars or galaxies get their spin?

It is my understanding that when a star, a planetary disk, or a galaxy forms, the rotational momentum of the whole system is conserved. Due to the smaller size of the resulting object, it will spin ...
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### Ramifications of black hole stellar system

Recently, I got around to seeing the movie Interstellar. In it, the characters of the movie visit a stellar system that appears to be built around a black hole instead of a star. On top of this, their ...
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### Can A Black Hole Exist?

In 1939, Robert Oppenheimer and other concluded that a certain neutron stars could collapse to black holes and no known law of physics would intervene. As far as I can tell, there is no observational ...
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### Can objects enter hydrostatic equillibrium through processes other than the influence of gravity?

Wouldn't a droplet of liquid (say water) floating around in space become spherical and "in hydrostatic equilibrium" due to surface tension but not gravity?
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### moonless night and lunar phase

How to define moonless night? There is no moon at all during some night? How to calculate and know whether the moon would appear during one night? If the lunar phase is full moon, is it possible ...
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### Is axial tilt direction correlated with semi-major axis direction?

Earth comes closest to the Sun every year around January 3. Winter solstice is at 21-22 December, merely some 12-13 days away. That means projection of Earth rotation axis onto the plane of its ...
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### What causes the bright white area in this photo of the earth?

Regarding the photo of the earth described here, I know that the green tinge on the left hand side is to do with the aurora borealis. What's causing the bright white light on the right hand side?
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### Is Zeta Reticuli within the Orion Arm?

My research has told me astronomers have labeled the galaxy arm that our system is located the Orion Arm but I have yet to find out if that also applies to Zeta Reticuli or not (not asking about ...
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### Appropriate battery for overnight viewing to drive telescope and GOTO?

I have a Plettstone 18" Dobsonian telescope with GOTO and clock drive that runs off a 12 volt cigarette lighter adapter. What is an appropriate battery to use to run this overnight while viewing all ...