Astrophysics

Astrophysics is the scientific discipline concerned with the events that are taking place on the grandest of stages; the universe. Questions about the formation and evolution of the planets, solar systems, stars, and galaxies found within the universe, as well as questions regarding black holes, cosmic rays, particle and nuclear astrophysics, nucleosynthesis, and magnetohydrodynamics should be directed here.

5,235 Questions
Astrophysics
Particle Physics

What is a space rift?

A space rift is that event in space in which everything (even subatomic particles) gets torn apart due to the growing repulsion from dark energy destroying nearly every galaxy present.

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Astrophysics

Interstellar gas is composed mainly of?

Interstellar gas is made of mainly hydrogen. This is because that is the building for everything and hydrogen is the most common element in the universe.

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Stars
Black Holes
Astrophysics
Betelgeuse

Is Betelgeuse a black hole?

No, it is a red supergiant star.

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Astronomy
Planetary Science
Astrophysics
The Solar System

How old is the solar system?

The Sun is about 4.57 billion years old, so is the solar system.

The age of the Solar System is determined through the radiometric dating of heavy elements such as uranium. Measurement of radioactive decay rates allow us to determine when the elements in the Solar System were formed.

The most current data places the age of these elements at 4.567 billion years old. This gives us an upper limit for the age of the Solar System. However, these 4.567 billion-year-old elements were formed by a nearby supernova, and the time it took them to travel from the location of the supernova site to the hydrogen cloud whose gravitational collapse into the Solar System by these elements is at present uncertain. Also uncertain is the precise amount of time it took for the collapse to complete from beginning to end. However, our best estimates place the age of the Solar System at 4.5 to 4.55 billion years.

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Physics
Black Holes
Astrophysics

What is the study of black holes called?

There is a super rare name for a black hole and its the biggest black hole ever and also the sicentists are hideing it from us. And the black hole name is Cronoid; its called Cronoid because it have lots of bones; no one knows why there are bones??

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Black Holes
Cosmology
Astrophysics

Are black holes high density objects?

Yes and No - While the current measure for the mass of a black hole is based on an indirect measuring of the speed of the orbiting material, there is no direct measuring of the density of a black hole.

Density is a concept involving mass divided by volume. While one can abstract the mass of a black hole, measuring the volume is a little tricky. We know there is a boundary at the Schwarzschild radius (Schwarzschild horizon) and this is also called the event horizon. Bascially, anything that happens beyond that point is unknown to us. Supermassive black holes have properties which distinguish them from lower-mass classifications. First, the average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some supermassive black holes. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, the density of a black hole is inversely proportional to the square of the mass, and thus higher mass black holes have lower average density.

To complicate things even more, space-time is highly distorted around a black hole, so even asking how big it is, adds further complexity to this answer. Nonetheless, black holes have a mass and size. However one can not know if the mass inside is accreted all at one point or more spread out and distibuted. It appears the inner dynamics of the black hole provide for a plasma like accretion disk, which that pretty much changes (or distorts) our traditional dimensional frame of reference. It could be that the black hole merely suspends acquire mass in a medium of energy state. Consequently this medium of energy may preclude its growth or shrinkage.

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Black Holes
Astrophysics

What is the safe distance for a black hole?

A bit beyond its event horizon

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Black Holes
Astrophysics

Who studies black holes and the subatomic particles that radiate from them?

They are studied by astrophysicists which is a branch of astronomy dealing especially with the behavior, physical properties, and dynamic processes of celestial objects and phenomena.

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Stars
Black Holes
Astrophysics

How do black holes form?

A black hole forms when any object reaches a certain critical density, and its gravity causes it to collapse to an almost infinitely small pinpoint. Stellar-mass black holes form when a massive star can no longer produce energy in its core. With the radiation from its nuclear reactions to keep the star "puffed up," gravity causes the core to collapse. The star's outer layers may blast away into space, or they may fall into the black hole to make it heavier. Astronomers aren't certain how supermassive black holes form. They may form from the collapse of large clouds of gas, or from the mergers of many smaller black holes, or a combination of events

When a huge star dies it's core becomes so dense it's own gravity starts to crush and collapse inwards the heart of a black hole is called the (Singularity)

when an red gaint star dies then it loses all its gaseous material and an empty space form through which light also cannot escape then they are called as black holes

when a star loses enough molecules that it cannot sustain its massive size, its own gravity forces the star to collapse on itself and create a neutron star. but if the original star is large enough, the neutron star's neutrons will be crushed forming a black hole

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Astronomy
Planetary Science
Black Holes
Astrophysics

How does gravity affect light in a black hole?

It doesn't make much sense if you apply it to a Newtonian point of view, but in an Einstein point of view, with the theory of relativity, specifically the idea of gravity stemming from spacetime.

I'm pretty sure most of us have seen the grid analogy of gravity, with a picture of Earth and a grid dipping around it.

While we don't entirely understand black holes, in the theory of relativity, light would normally just go through the dip and back up, with little curvature. In a black hole, the light travels over that dip, but the exception is with black holes, is that it isn't just a dip, it literally makes a hole in spacetime. The light will travel into it, and be well, dissolved by the black hole.

This probably isn't a fully scientific explanation, but this is how I see it, from what I have read it.

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Hubble Space Telescope
Astrophysics

When was seti created?

SETI began in 1984

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Astrophysics

What is the planet finding group ending in ETI?

S.E.T.I.

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Black Holes
Astrophysics

Is Neptune close to a black hole?

No, Neptune is not near any detectable black hole. The closest black hole is about 7,800 light years away from Earth.

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Astronomy
Black Holes
Astrophysics

How does a quasar burst away from a black hole if the black hole has infinite gravity?

It's only infinite around the event horizon.

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Black Holes
Astrophysics

How was a star formed as a black hole?

A star is formed into a black hole by exploding into it. Here is how it works when a star gets to old it grows a little bigger and then smaller then explodes this scientific process is known as a super nova. In order to become a black hole it needs to have a proper size. For example, when the sun has a super nova it will move or destroy about the first four planets in the solar system and when might become a black hole (even though its a midsized star) it might even swallow the last four planets. The end of a black holes life might create another solar system. But first the black hole has to become or form into nothing but just a cloud in space, just two atoms and or cells. Keep this in mind. when there are just two atoms or cells in space that are together, they just start hitting each other again and again until they combine there self's then star of as a really small star. For more information go to http://www.universetoday.com/24190/how-does-a-star-form/

PS I'm a ten year old fifth grader and I know all this stuff since first grade and I answer a lot of questions here.

And i just created an account here too.

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Astronomy
Black Holes
Astrophysics

What is on the other side of the universe?

[Note: This is an astronomer's answer. There are numerous answers in series here, so if this one is too long, technical, or you just don't like it, see the numerous other answers beneath it!]

It depends on what you mean: 1) just farther than we can currently see in our observable universe or 2) outside ofour Universe.

1) Very, very far away, farther than we can currently observe:

To the best of our current observations and theory, the Universe on the largest scales is homogeneous (i.e. 'smooth', or of similar density, composition, etc.) and isotropic (it looks the same in every direction). So, no matter where you are within our Universe, it should be about the same. That's the short answer.

Let me point out that our Universe has a finite and well-determined age; recent measurements put it at a little over 13 billion years (roughly 3 times the age of the solar system/Earth). There is a limit to how far away we can see--13 billion light-years--because the universe is only 13 billion years old, and light from farther away hasn't had time to get to us yet. This DOES NOT mean that the Universe is only 13 billion light-years in radius, and we are at the center of it; it is only our observable universe that is that size. As time passes, the size of our observable universe increases at the speed of light.

The actual size of our Universe is much larger; we just can't see it. So, to an observer farther than 13.4 billion light-years from us, outside our observable universe, things probably look about the same as they do here, but we won't know for sure until enough time passes for light (and gravity waves, neutrinos, whatever) arrive from there for us to observe.

Note that is is an assumption--that everywhere is about the same as it is here, and we're not at the center of the universe*(see below for why astronomers think this). This assumption is true for the amount of the universe we can observe, so most astronomers assume that it is true in general.

Expansion of the universe

How do we know we're not at the center of the universe? We observe the light from distant galaxies to be redshifted, which means that the galaxy is moving away from us very quickly. (Look up the Doppler effect; we hear the same effect from a moving sound source, such as a police car siren getting lower in pitch when the police car is moving away from us.)

Light from almost every galaxy, except those nearest to us (Andromeda, the Virgo cluster) is redshifted, meaning that everything is moving away from us, except for a few nearby galaxies. We can conclude that either: a) we are at the center of the universe, or b) space itself is expanding, and everygalaxy sees most other galaxies moving away from it! We think it is b), that space is expanding. You can understand this in two dimensions by taking an uninflated balloon and marking some dots on it. Now, inflate the balloon. Every dot gets farther away from every other dot. Our universe works the same way in three dimensions.

So, that brings up the question---if our Universe is expanding, what is it expanding into?

2) Outside our Universe: The cheap answer is that we can never know, since by definition it is beyond our universe. That's the best answer we can currently give, based on observations and generally-accepted theory.

There is no 'edge' to our Universe; even if you were able to somehow able to travel faster than light, and go beyond our observable universe, you would never encounter an edge, no matter how far you looked. Likewise, the Earth is finite in size, but there is no edge to the Earth; it's a curved surface. Mathematicians would call this a 2-dimensional surface of positive curvature, embedded in 3 dimensions---you can travel around the earth, and eventually end up where you start. The universe works the same way, except that it is a three-dimensional curved surface embedded in four (spatial) dimensions. Just like we can't find the center of the Earth anywhere on its surface, there is no center to the Universe that we can find, because we are stuck on its 3-dimensional surface; the center is in a higher dimension. (I know that sounds bizarre!)

Incidentally, current observations show that our universe has negative curvature, the opposite of a sphere; (it will expand forever, and you could never travel in one direction and end up where you began like you can on surfaces of positive curvature such as the Earth).

As for what the fourth spatial dimension is that we can't observe because it is OUTSIDE OUR 3-D Universe, it is beyond what current science can answer. Read the numerous other answers to this question below for other peoples' thoughts on this.

No one knows whats on the Other Side of the UniverseThe answer to the question "What is on the other side of the universe" is very simple, that is, no one knows yet. But perhaps if we were to wait about 500 or more years maybe, and just maybe, there will be some sort of respectable answer based somewhat more on accumulated facts than on imaginary theories.

How would we know? Are we ever GOING TO GET THERE? Well, build a time machine and go into the future so we can see if we will, but we can't do that right now.

The Other Side of the UniverseRecently it has been observed that the farthest objects we can see are not only traveling outwards at great speed but also accelerating. (It is my personal belief that) God gave the galaxies their initial thrust but to be accelerating there must be some other force being exerted too. One feasible explanation is that there are similar bodies near enough to pull the outer regions of our Universe outwards. These bodies would be part of our universe, but perhaps not observable to us from our vantage point. Another explanation being taken seriously is a repulsive force that we have not yet observed that would be pushing the outer galaxies farther and farther away. AnswerThere is no other side of the universe. The four dimensional geometry of space and time is such that wherever you are in the universe seems to you to be the center. However, the universe seems to be fairly homogeneous. Wherever you are you would find mostly empty space with galaxies of stars consisting mostly of hydrogen, and planets orbiting the stars. AnswerHere are more comments from WikiAnswers contributors:
  • In actuality, the Universe is an ellipsoid (3 dimensional oval) in which as someone else stated, you always seem to be at the center due to the vastness and gravitational forces. In theory, the end of the universe (if possible to reach) would be impossible to see because light bends as it hits the end, so if you could see far enough (provided noting impairs your sight) you would be looking at the back of yourself. Outside of our universe is many other universes which (may) be reached by use of black holes. What these universes are suspended in is unknown, the most likely answer being infinite nothingness.
  • It would be everything else other than the singularity that became the physical universe as we know it just before the big bang.
  • There is a theory that "on the other side of the universe" there is another universe. However, it's not a popular theory.
  • There are several theories. Some hypothesize that the universe is ever-expanding and infinite. However, that raises some questions. What is the universe expanding into? What is in the emptiness the universe is not yet occupying? Will we ever hit a wall? It is safe to say that if the universe ever did hit a wall, it would not affect earth, or even our galaxy. Einstein theorized that it is possible that there are two universe, connected by a wormhole. Others say that the 'big bang' that created us was a 'splat' from another, older, parallel universe that was having a violent episode. The material from that 'splat' surged into emptiness, so much so that it created an alternate continuum, and then exploded as a huge white hole, creating our universe. They also say it's been expanding since then. Some experts, as Steven Hawking, believe that all the matter in the universe was at one time compacted into something small, the size of a marble maybe. It was incredibly massive or perhaps more accurately, incredibly energetic. It is currently believed that there were no actual physical particles present. It had an explosive reaction to something, and bang--hello universe. There's much more, of course, but this is already a long answer.
  • The universe, according to Einstein, is circular. All of space and matter is observably distorted or warped by gravitational fields, and all of the universe is encompassed in one gigantic gravitational field. If the universe is indeed closed, then if you traveled in any direction in a straight line you would (assuming you didn't run into a planet or black hole or something) eventually come back to the same exact spot. This concept is the basis for the hoaky but interesting movie "the paycheck" with Ben Affleck.
  • According to the newly emerging "Membrane" Theory, or Brane Theory, the universe as we know it is really a membrane, or flexible bumpy plane (or so it would seem to the quantum elves who can see things in the 11 dimensions theorized to be necessary for certain things to occur). Our membrane is one of perhaps countless membranes. They are all around us, everywhere. "Closer to us than our skin", as one physicist remarks. When 2 membranes collide, the result is... a new universe. Black holes may be evidence that such a collision has happened.
  • Maybe the universe is whatever we want to think it is. I think that no human will ever really know, and heck, maybe nothing's real. Yet again, no one really knows.
  • We can't see any edge of the universe. It might be infinite, in which case it has no center and no "other side". So astronomers often talk about the "observable universe". This is because it's not possible to see things more than a certain distance away, because the time it would have taken the light to get here is longer than the age of the universe. But if you change the question to ask about the observable universe then it still doesn't make sense, because we're at the center of the observable universe. (Think about it.) If you ask "what is at the furthest reaches of the observable universe" then the answer is that as far as we can tell it's pretty much the same everywhere (on a large scale). Every part of the universe has galaxies of various shapes and sizes.
  • There must be something beyond our universe that is different from space-time as we know it. We all know about the big bang theory that suggests that space-time was created between 10 and 20 billions of years ago. Hence, space-time is absent outside the universe since the big-bang didn't create the 'area' outside our universe. However, we can't conclude that there is nothing there. So, we can say that there is something other than space-time present. Perhaps it is emptiness. Who knows?

These things are so enjoyable to ponder. We are so locked in to our amazingly tiny view of the universe relative to both space and time that we are surely not yet open to some Very Big Ideas that will 'change' everything. At one time, intelligent thinking people could not fathom the idea that the earth is a globe moving in an orbit around the sun. People once considered it obvious and common-place that animals sprang whole from various kinds of plants. Surgeons didn't hesitate (it was a brutal business back then) to cut into people without even a simple soap and water wash of their hands, or of their instruments. Even into the 20th century, some were convinced that travel to the moon and other bodies in space was absolutely and fundamentally impossible-- not because of technology but because of natural unbreakable limits and laws. People are just now 'getting' that time is relative.

Regarding the 'edges' of space, people are probably right who argue that no matter where you are you will appear to be in the center. One of those Very Big Ideas (that I make no claim to understand) is that the 'border' of space is itself three-dimensional, and therefore not reachable in anything like a conventional sense. We move in three dimensions, so there is no place we can go, and find ourselves in something other than a three-dimensional space. There is really nothing 'beyond', unless you break through the tiny theorized dimensions locked fast in the mysterious quantum. Even then, anyplace else that could possibly exist would not be 'outside' of our universe but parallel to it.

We haven't even mentioned the possibility (there is evidence in support of this) that space itself is expanding, and this may in part account for the redshift in our observations of distant galaxies.

  • One could say that we are on the other side of the universe. There truly is no "Wall" per say in the universe. The universe is a curve. If one follows the curve, one will eventually end up exactly where one started.
  • I do have a hypothesis about the universe "looking" like its spreading, If the Earth orbits the Sun and the Sun orbits the center of the galaxy, maybe all galaxies orbit something even bigger. which would make it look like it was spreading but really has the effect of a horse race. (they start at the same place but the slower horses gets left behind and the fast ones get farther from the others) so it would be thinning instead if spreading.
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Astronomy
Black Holes
Astrophysics

Can the sun cause a black hole?

No. Our Sun isn't massive enough to become a black hole. Only stars greater than three solar masses can become black holes.

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Astronomy
Space Travel and Exploration
Black Holes
Astrophysics

Are there black holes in space xy?

There are black holes in space, probably the most famous is the one in the constellation of Cygnus (the swan) and is called cygnus X1, there is also thought to be a giant black hole at the centre of the galaxy.

The gravity of a black hole is so strong that once inside the edge known as the event horizon nothing can escape not even light. Therefore we do not know what is like inside and even if we sent someone in to investigate they would never be able to tell us because their communication would not be able to get out.

If someone went inside the event horizon they would die fairly quickly, the difference in gravitational pull between your toes and your head would stretch you out like a long piece of spaghetti altough with very massive black holes you will not spaghettify until the moment you come very close to the hole.

At that point tidal forces would eventually rip you apart, then rip your atoms apart and you would eventually become more of the black hole's mass.

There is speculation that space could become so warped and distorted the very fabric of reality is broken down which leaves the door open to just about anything but that borders on meta-physics.

Depending on the side of the black hole it is possible that turbulance around it may prevent you from actually reaching the outer shell of the black hole called the "Event Horizon". Once past that point, there is no escape back outside of the horizon (currently) but you could survive within the event horizon for a period of time (current theory at this time) but eventually you will meet your doom at the center.

If you were to travel directly towards one, without going inside. More then likely you would see a weird distortion as light from objects behind it are bent around it. As you got closer you would more then likely see a growing blank spot. If you are travelling directly at it you would then be sling shot around it and off on your merry way.

If you approach it just right you would get locked into an orbit around it seeing again a weird warped image of the objects around it. Given yourself a bit of a push and you can start to fall inwards towards the mass.After that, you go right in and die.

Yes -there are many black holes in the universe. It's believed that at the center of each large galaxy, there lies a black hole.

Supposing you tossed a ball into a black hole, it would reach relativistic speeds fairly quickly, so time for the ball would appear to be very different. To you, it would appear as though the ball would slow down and stop before it reached the black hole. To an ant on the ball, it would appear as if the universe around it sped up, aging billions of years, and eventually reaching an "infinite time" before it hit the black hole.

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Sports
Writing and Composition
Astrophysics

What is a brief description of each major American sport?

Answer

American football is a sport where two opposing teams attempt to score points by moving an inflated oval ball past a goal line. The ball can be advanced by carrying the ball or throwing it from one teammate to the other. Points are scored when a member of either team carries the ball across the opposing team's goal line and into their end zone, or when the ball is kicked from anywhere in the field of play and through the upright goal posts. The team with more points when time has expired wins. It is sometimes considered the most popular spectator sport in the United States. The major professional league is the NFL.

Basketball is a sport in which two teams of five players each try to score points by throwing a ball through a hoop. It is primarily an indoor sport, played in a relatively small playing area, called the court. The speed and grace of the game, combined with the close proximity of the spectators to the action, make basketball an exciting spectator sport. It is one of the most popular sports in the United States, and is also popular in other parts of the world.

Ice hockey is a team sport played on ice. It is one of the world's fastest sports, with players on skates capable of going high speeds on natural or artificial ice surfaces. It is very popular in Canada but has a comparably strong following in certain regions of the United States, notably the Northeast, the Northern Midwest, and Alaska.

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Social Sciences
Black Holes
Astrophysics

What does black hole means?

A black hole is a super-dense object in space, usually a star, which has become so massive it has collapsed in upon itself. The mass of such an object is so great that the gravitational field it creates pulls in everything nearby. As an object draws closer to a black hole, the gravity exerted upon it becomes more powerful, requiring more and more energy to counter the curvature of space. The speed it would take to overcome this curvature and pull away from the black hole is known as escape velocity.

When an object draws close enough that its escape velocity exceeds the speed of light, the upper limit of how fast any object in the universe can travel, that object is trapped and will inexorably move in towards the center of the black hole, known as the singularity. The point at which the escape velocity exceeds the speed of light is called the event horizon. Nothing which has passed that point will ever return to normal space.

As indicated above, the gravity of the singularity is so strong that nothing, even light itself, moves fast enough to escape the pull. The inability of light to get away from the object is what gives the black hole its name.

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Astronomy
Planetary Science
Stars
Neutron Stars
Astrophysics

How are neutron stars and blackholes related?

Both are remainders of stars, that ran out of fuel. (So are white dwarves.)

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Black Holes
Astrophysics

Can planets go through black holes?

Yes as a matter of fact they can, but what comes through the other side is something you wont recognize because it has been broken down into the very atoms that make everything in the universe.

In essence there's nothing left for you to see and it could take billions of years for it to pass all the way through the black hole.

Very Violent and very intriguing.

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Astronomy
Cosmology
Astrophysics

What conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

The actual presence of the gas cloud's contents will absorb certain wavelengths of Light, preventing the passage of certain photons through the cloud, that results in that Light not reaching us - producing a blank line in the observed spectrum.

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Planetary Science
Black Holes
Astrophysics

Do black holes really exist?

Yes. It is generally considered that both the theory of black holes is quite sound, and that the observational evidence is quite firm.

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Black Holes
Stephen Hawking
Astrophysics

Who discovered black holes?

Black holes have a long history; John Michel figured out some 200 years ago that something like "black holes" should exist, if it were possible to concentrate matter into a tiny space. The modern theory of black holes is somewhat different from Michel's arguments, though. Specifically, the modern theory of black holes is based on the General Theory of Relativity.

The actual discovery was more recent, and it took a while to recognize the X-rays observed, as black holes.

I suggst you read about "black holes" in Wikipedia, for example, to get a more thorough description of the theory - and also of the history.

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