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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.
1,304 Questions
How do you escape a black hole?
Some theories state that if you enter a black hole at a certain trajectory you can exit via a white hole in another part of our universe or different universe. Other than this there is no escape from a black hole. Hawking radiation excepted.
How do you measure the size of a black hole?
The size of a quasar can be inferred from the timescale of variations in its light output.
Assuming that no signal can travel across the source faster than the speed of light, the
time scale of the fastest variations sets an upper limit on the size of the quasar (i.e., size quals approximately the variation timescale times speed of light).
An alternative method called 'reverberation mapping' monitors changes in the quasar's light output, then looks for these same changes in the light output from specific spectral lines. The delay times the speed of light gives the size of the quasar.
How big would the sun be if it was a black hole?
Firstly our sun is too small to become a black hole. Only stars that are a million to a billion times our sun do this, because they burn through their fuel quickly, unlike our sun.
A typical black hole has 3 times the mass of our sun
How long to walk around the planet?
It would take an incredibly long time to walk around the entire planet, estimated to be about 25,000 miles in circumference. Walking non-stop at an average pace of 3 miles per hour, it would take roughly 3,000 hours or 125 days to complete the journey. However, this is not a feasible or realistic endeavor for a single person due to factors like terrain, weather, and logistics.
Cosmic rays are electromagnetic energy - like light. They quite naturally travel at the speed of light, which is 299,792,458 meters per second. Note that the cited speed applies to a vaccuum. Their speed appears to be less when they are passing through air or another medium.
Sorry, I believe that this is incorrect. Cosmic rays are not light consisting of photons. At least 90% of them are high energy particles that consist of protons. They may be able to move close to the speed of light, but do not travel at the speed of light.
How and when were black holes discovered?
Black holes were described theoretically before evidence for their existence was collected from astronomical observations. The philosopher and geologist John Michell in the late 18th century described what would happen to infalling matter approaching a body of a certain mass where it had sufficient acceleration from gravity to approach the speed of light, and proposing the idea that light theoretically emitted by it would be unable to escape; but it wasn't until Einstein's General theory of Relativity (1915) that the framework of gravitation was in place and the reality of black holes could be described mathematically. Building upon Einstein's work, the effect of gravity on space was much better understood and solutions to his field equations yielded much more accurate models of black holes' properties and reinforced the theoretical evidence for their existence. Observational evidence came later, but because black holes cannot emit light, the evidence was indirect, in the form of certain x-ray sources, relativistic jets, quasars or galactic nuclei, and orbital motion near massive bodies. Credit for discovery of the first strong black hole candidate through astronomical observation in an X-ray binary system (Cygnus X-1) goes to Bolton, Murdin, and Webster in 1972.
Should you be scared about a black hole?
Black holes are incredibly fascinating but also very distant. Unless you are in close proximity to one, there is no need to be scared as they are not a threat to us on Earth. They are important in understanding the universe and how gravity works.
How far is it in light years to the nearest suspected black hole?
Back in 2000, scientists suggested that the flare-up of a visible star, designated V 464, possibly revealed the presence of a micro quasar (a type of black hole system) as close to the Earth as 1,600 light years away.
What happen if a quark star accidentally collide with a black hole?
If a quark star were to collide with a black hole, several outcomes are possible depending on the mass and velocity of the objects. Potential scenarios include the quark star being devoured by the black hole, leading to an increase in the black hole's mass, or a violent event such as the emission of gravitational waves and high-energy particles. These collisions are complex phenomena that are still being studied by scientists.
What shape does a black hole have?
there is still no proper answer about the structure of a black hole,as because a black hole cant be seen.But according to assumptions the black hole spins around and thus its structure may be oval or spherical.Like anything thaat rotates, the black holes becomes flatter at the poles and broader at he equator
What is the lifespan of a small black hole?
when a red supergiant dies it goes super nova and under the tremendous force of its own explosion it collapse into itself and becomes a black hole. for one to form a large star has to go through its entire life span and die. this usually takes about 9 billion years.
How many different types of black holes are there?
There are four types of black holes. In size and physical construct.
Size:
- Supermassive: These have a mass of between 105 -> 109 million Suns yet have a diameter of 0.001 -> 10 AU (an AU is approximately 150 million kilometers). It is believed that most, if not all galaxies have a supermassive black hole in their centre.
- Intermediate mass black hole. These have a mass of around 103 million Suns yet have a diameter of 103 kilometers (About the radius of Earth)
- Stellar-mass. These have a mass of about 10 million Suns but are only around 30 kilometers in diameter.
- Micro black hole. These have the mass of a million Moons but are tiny, up to 0.1 mm in diameter.
Physical construct:
- Black holes with no electrical charge, and without rotation
- Black holes with no electrical charge, and with rotation
- Black holes with an electrical charge, and without rotation
- Black holes with an electrical charge, and with rotation.
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Could other black holes get near Earth?
The closest known black hole to Earth is over 1,000 light-years away, so the likelihood of another black hole getting near Earth in the foreseeable future is extremely low. Additionally, the vast distances and rare occurrences of black holes make it highly improbable for one to come into close proximity to our planet.
Light bends when it passes near the gravitational field of a black hole due to the curvature of space-time caused by the intense gravity of the black hole. This effect is known as gravitational lensing, and it can cause light to follow a curved path around the black hole rather than a straight line.
What does searching for black holes involve?
Imagine you are looking into space. You see a small group of stars, and pinpoint where they are. Then you come back a short time later, and you'll see that they moved, and not only that, but all of them in the same circular motion. The star that was on the top might now be on the right. The center of this circle is very likely a black hole. These stars are going around that point so fast that the gravity must be extremely strong, and only black holes have such gravitational pull on other masses.
How far is the closest black hole?
The closest known black hole to Earth is about 1,000 light-years away in the constellation of Monoceros. It is known as V616 Monocerotis or A0620-00. It is a stellar-mass black hole formed from the remnants of a massive star.
What do clusters of galaxies form?
Clusters of galaxies form due to the gravitational attraction between individual galaxies in a region of space. Over time, these galaxies are pulled together by their mutual gravity to create a cluster structure. The largest clusters are held together by dark matter, which provides the majority of the mass in the system.
Spiral galaxies form from the collapse of a protogalactic cloud. Spiral galaxies consist of three components: a rotating disk, a bulge and a halo. Spiral galaxies, like the Milky Way, owe their shape to stars inside the protogalaxy developing at different intervals. The gas between forming stars continues to be compressed, and the resulting gravitational differences manhandle the protogalaxy's stars, dust and gas. When the protogalactic cloud collapses, the stars in the bulge and halo form first. These stars have rather random orbits around the galactic center. The galactic center probably contains a supermassive black hole, which likely exerts some gravitational influence on the formation of a spiral galaxy.
The remainder of the cloud forms a disk due to the conservation of angular momentum (the same effect as the spinning up of the dancer when she pulls her arms inside). This motion forces everything into a rotating disk, and additional differences in gravity build the spiral arms. Oppositely, when a protogalaxy's stars develop at the same time, you have an elliptical galaxy on your hands. The stars in the disk form later and thus the disk population of stars are younger than those in the bulge and the halo. Further, the stars in the disk rotate around the center of the galaxy in a collective, well defined way unlike the stars in the bulge and halo.
"Output" is the something that gets out of something, usually in the sense of "result". Often it is used for results that a computer shows on a screen, or sends to a printer to print on paper.
What is the closest black hole?
In April 2008 NASA discovered the smallest black hole ever. The black hole, called XTE J1650-500, is15 miles across. It is located in Ara, a constellation in the Milky Way Galaxy.
In the astronomical sense of the word (as opposed to a hole that a worm eats through an apple, for example) worm holes remain theoretical objects; none have ever actually been observed. Therefore we cannot say that they are real, at this point, although someday we might discover that they are. Or perhaps we won't.
Have any black holes been found by NASA recently?
Yes there is!
This is the article I found on NASA.gov
PASADENA, Calif. - Astronomers have unmasked hundreds of black holes hiding deep inside dusty galaxies billions of light-years away.
The massive, growing black holes, discovered by NASA's Spitzer and Chandra space telescopes, represent a large fraction of a long-sought missing population. Their discovery implies there were hundreds of millions of additional black holes growing in our young universe, more than doubling the total amount known at that distance.
Image right: This image, taken with Spitzer's infrared vision, shows a fraction of these black holes, which are located deep in the bellies of distant, massive galaxies (circled in blue). Image credit: NASA/JPL-Caltech/ Commissariat a l'Energie Atomique
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"Active, supermassive black holes were everywhere in the early universe," said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. "We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself." Dickinson is a co-author of two new papers appearing in the Nov. 10 issue of the Astrophysical Journal. Emanuele Daddi of the Commissariat a l'Energie Atomique in France led the research.
The findings are also the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths building monstrous black holes at their cores.
For decades, a large population of active black holes has been considered missing. These highly energetic structures belong to a class of black holes called quasars. A quasar consists of a doughnut-shaped cloud of gas and dust that surrounds and feeds a budding supermassive black hole. As the gas and dust are devoured by the black hole, they heat up and shoot out X-rays. Those X-rays can be detected as a general glow in space, but often the quasars themselves can't be seen directly because dust and gas blocks them from our view.
"We knew from other studies from about 30 years ago that there must be more quasars in the universe, but we didn't know where to find them until now," said Daddi.
Image left: An artist's concept of a growing black hole. Image credit: NASA/JPL-Caltech
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Daddi and his team initially set out to study 1,000 dusty, massive galaxies that are busy making stars and were thought to lack quasars. The galaxies are about the same mass as our own spiral Milky Way galaxy, but irregular in shape. At 9 to 11 billion light-years away, they existed at a time when the universe was in its adolescence, between 2.5 and 4.5 billion years old.
When the astronomers peered more closely at the galaxies with Spitzer's infrared eyes, they noticed that about 200 of the galaxies gave off an unusual amount of infrared light. X-ray data from Chandra, and a technique called "stacking," revealed the galaxies were, in fact, hiding plump quasars inside. The scientists now think that the quasars heat the dust in their surrounding doughnut clouds, releasing the excess infrared light.
"We found most of the population of hidden quasars in the early universe," said Daddi. Previously, only the rarest and most energetic of these hidden black holes had been seen at this early epoch.
The newfound quasars are helping answer fundamental questions about how massive galaxies evolve. For instance, astronomers have learned that most massive galaxies steadily build up their stars and black holes simultaneously until they get too big and their black holes suppress star formation.
The observations also suggest that collisions between galaxies might not play as large a role in galaxy evolution as previously believed. "Theorists thought that mergers between galaxies were required to initiate this quasar activity, but we now see that quasars can be active in unharassed galaxies," said co-author David Alexander of Durham University, United Kingdom.
"It's as if we were blindfolded studying the elephant before, and we weren't sure what kind of animal we had," added co-author David Elbaz of the Commissariat a l'Energie Atomique. "Now, we can see the elephant for the first time."
The new observations were made as part of the Great Observatories Origins Deep Survey, the most sensitive survey to date of the distant universe at multiple wavelengths.
Consistent results were recently obtained by Fabrizio Fiore of the Osservatorio Astronomico di Roma, Italy, and his team. Their results will appear in the Jan. 1, 2008, issue of Astrophysical Journal.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.
The National Optical Astronomy Observatory is operated by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation.
Hope it helps!!!
What is the difference between astrophysics and aerospace?
Astrophysics is a branch of Physics. It deals with the study of the universe, including the physical properties (luminosity, density, temperature, and chemical composition) of celestial objects such as galaxies, stars, planets, exoplanets Aerospace engineering is the branch of engineering behind the design, construction and science of aircraft and spacecraft. Aerospace engineering has broken into two major and overlapping branches: aeronautical engineering and astronautical engineering. Aeronautical deals with craft that stay within Earth's atmosphere, and Astronautical deals with craft that operate outside of Earth's atmosphere.
Has there ever been a black hole and what does it do?
yes, there is actually a giant black hole in the center of our galaxy, but don't worry because we are safely orbiting around it. A black hole is basically really really really dense material, which forms a blob where the gravitational pull is so stong nothing can escape it, not even light. It can also bend the laws of physics
Do cosmic rays cause lightning?
No, cosmic rays do not cause lightning. Lightning is typically caused by the buildup of charge within a thundercloud, leading to a discharge of electricity to the ground. Cosmic rays are high-energy particles from space that can interact with Earth's atmosphere but do not directly cause lightning.
