Black Hole

Black Hole

Browse

Search

Entertainment & Pop Culture
Geography & Travel
Health & Medicine
Lifestyles & Social Issues
Literature
Philosophy & Religion
Politics, Law & Government
Science
Sports & Recreation
Technology
Visual Arts
World History

On This Day in History
Quizzes
Podcasts
Dictionary
Biographies
Summaries
Top Questions
Week In Review
Infographics
Demystified
Lists
#WTFact
Companions
Image Galleries
Spotlight
The Forum
One Good Fact

Entertainment & Pop Culture
Geography & Travel
Health & Medicine
Lifestyles & Social Issues
Literature
Philosophy & Religion
Politics, Law & Government
Science
Sports & Recreation
Technology
Visual Arts
World History

Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.
Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.
Demystified Videos In Demystified, Britannica has all the answers to your burning questions.
#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.
This Time in History In these videos, find out what happened this month (or any month!) in history.

Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.
COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.
100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
Britannica Beyond We’ve created a new place where questions are at the center of learning. Go ahead. Ask. We won’t mind.
Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century. Learn about the major environmental problems facing our planet and what can be done about them!
SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!

While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.

Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).

Feedback Type

Select a type (Required)
Factual Correction
Spelling/Grammar Correction
Link Correction
Additional Information
Other

Articles from Britannica Encyclopedias for elementary and high school students.

While every effort has been made to follow citation style rules, there may be some discrepancies.
Please refer to the appropriate style manual or other sources if you have any questions.

Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).

Feedback Type

Select a type (Required)
Factual Correction
Spelling/Grammar Correction
Link Correction
Additional Information
Other

Articles from Britannica Encyclopedias for elementary and high school students.

By

The Editors of Encyclopaedia Britannica

Last Updated:

Aug 24, 2022

Edit History

Key People:

Reinhard Genzel
Kip Thorne
Andrea Ghez
Stephen Hawking
Subrahmanyan Chandrasekhar

... (Show more)

Related Topics:

accretion disk
event horizon
Kerr black hole
singularity
Penrose diagram

... (Show more)

What is the structure of a black hole?
What are some examples of black holes?
Uncover insight into the black hole
Mars and the Milky Way are more than just candy bars! See how much more you know about space with this quiz.

Get a Britannica Premium subscription and gain access to exclusive content.
Subscribe Now

Our editors will review what you’ve submitted and determine whether to revise the article.
Our editors will review what you’ve submitted and determine whether to revise the article.
A black hole is a cosmic body of extremely intense gravity from which even light cannot escape. Black holes usually cannot be observed directly, but they can be “observed” by the effects of their enormous gravitational fields on nearby matter.
The singularity constitutes the center of a black hole, hidden by the object’s “surface,” the event horizon. Inside the event horizon, the escape velocity exceeds the speed of light so that not even rays of light can escape into space.
A black hole can be formed by the death of a massive star. At the end of a massive star's life, the core becomes unstable and collapses in upon itself, and the star’s outer layers are blown away. The crushing weight of constituent matter falling in from all sides compresses the dying star to a point of zero volume and infinite density called the singularity.
One example of a black hole is can be found in Cygnus X-1, a binary X-ray system consisting of a blue supergiant and an invisible companion 14.8 times the mass of the Sun. Another example is Sagittarius A*, a supermassive black hole that exists at the centre of the Milky Way Galaxy.
black hole , cosmic body of extremely intense gravity from which nothing, not even light , can escape. A black hole can be formed by the death of a massive star . When such a star has exhausted the internal thermonuclear fuels in its core at the end of its life , the core becomes unstable and gravitationally collapses inward upon itself, and the star’s outer layers are blown away. The crushing weight of constituent matter falling in from all sides compresses the dying star to a point of zero volume and infinite density called the singularity .
Details of the structure of a black hole are calculated from Albert Einstein ’s general theory of relativity . The singularity constitutes the centre of a black hole and is hidden by the object’s “surface,” the event horizon . Inside the event horizon the escape velocity (i.e., the velocity required for matter to escape from the gravitational field of a cosmic object) exceeds the speed of light , so that not even rays of light can escape into space. The radius of the event horizon is called the Schwarzschild radius , after the German astronomer Karl Schwarzschild , who in 1916 predicted the existence of collapsed stellar bodies that emit no radiation. The size of the Schwarzschild radius is proportional to the mass of the collapsing star. For a black hole with a mass 10 times as great as that of the Sun , the radius would be 30 km (18.6 miles).
Only the most massive stars—those of more than three solar masses—become black holes at the end of their lives. Stars with a smaller amount of mass evolve into less compressed bodies, either white dwarfs or neutron stars .
Black holes usually cannot be observed directly on account of both their small size and the fact that they emit no light. They can be “observed,” however, by the effects of their enormous gravitational fields on nearby matter. For example, if a black hole is a member of a binary star system, matter flowing into it from its companion becomes intensely heated and then radiates X-rays copiously before entering the event horizon of the black hole and disappearing forever. One of the component stars of the binary X-ray system Cygnus X-1 is a black hole. Discovered in 1971 in the constellation Cygnus, this binary consists of a blue supergiant and an invisible companion 14.8 times the mass of the Sun that revolve about one another in a period of 5.6 days.
Some black holes apparently have nonstellar origins. Various astronomers have speculated that large volumes of interstellar gas collect and collapse into supermassive black holes at the centres of quasars and galaxies . A mass of gas falling rapidly into a black hole is estimated to give off more than 100 times as much energy as is released by the identical amount of mass through nuclear fusion . Accordingly, the collapse of millions or billions of solar masses of interstellar gas under gravitational force into a large black hole would account for the enormous energy output of quasars and certain galactic systems.
One such supermassive black hole, Sagittarius A* , exists at the centre of the Milky Way Galaxy . Observations of stars orbiting the position of Sagittarius A* demonstrate the presence of a black hole with a mass equivalent to more than 4,000,000 Suns. (For these observations, American astronomer Andrea Ghez and German astronomer Reinhard Genzel were awarded the 2020 Nobel Prize for Physics.) Supermassive black holes have been detected in other galaxies as well. In 2017 the Event Horizon Telescope obtained an image of the supermassive black hole at the centre of the M87 galaxy. That black hole has a mass equal to six and a half billion Suns but is only 38 billion km (24 billion miles) across. It was the first black hole to be imaged directly. The existence of even larger black holes, each with a mass equal to 10 billion Suns, can be inferred from the energetic effects on gas swirling at extremely high velocities around the centre of NGC 3842 and NGC 4889, galaxies near the Milky Way.
The existence of another kind of nonstellar black hole was proposed by the British astrophysicist Stephen Hawking . According to Hawking’s theory, numerous tiny primordial black holes, possibly with a mass equal to or less than that of an asteroid , might have been created during the big bang , a state of extremely high temperatures and density in which the universe originated 13.8 billion years ago. These so-called mini black holes , like the more massive variety, lose mass over time through Hawking radiation and disappear. If certain theories of the universe that require extra dimensions are correct, the Large Hadron Collider could produce significant numbers of mini black holes.

Intense X-ray flares thought to be caused by a black hole devouring a star. (Video)
Astronomers have identified a candidate for the smallest-known black hole. (Video)
This chart shows the relative masses of super-dense cosmic objects.
Don't let the name fool you: a black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City. The result is a gravitational field so strong that nothing, not even light, can escape. In recent years, NASA instruments have painted a new picture of these strange objects that are, to many, the most fascinating objects in space.

The idea of an object in space so massive and dense that light could not escape it has been around for centuries. Most famously, black holes were predicted by Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the Sun, the equations showed, the force of gravity overwhelms all other forces and produces a black hole.

Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion. A similar process can occur if a normal star passes close to a black hole. In this case, the black hole can tear the star apart as it pulls it toward itself. As the attracted matter accelerates and heats up, it emits x-rays that radiate into space. Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on the neighborhoods around them - emitting powerful gamma ray bursts, devouring nearby stars, and spurring the growth of new stars in some areas while stalling it in others.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.) If the total mass of the star is large enough (about three times the mass of the Sun), it can be proven theoretically that no force can keep the star from collapsing under the influence of gravity. However, as the star collapses, a strange thing occurs. As the surface of the star nears an imaginary surface called the "event horizon," time on the star slows relative to the time kept by observers far away. When the surface reaches the event horizon, time stands still, and the star can collapse no more - it is a frozen collapsing object.

Even bigger black holes can result from stellar collisions. Soon after its launch in December 2004, NASA's Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts. Chandra and NASA's Hubble Space Telescope later collected data from the event's "afterglow," and together the observations led astronomers to conclude that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.
Although the basic formation process is understood, one perennial mystery in the science of black holes is that they appear to exist on two radically different size scales. On the one end, there are the countless black holes that are the remnants of massive stars. Peppered throughout the Universe, these "stellar mass" black holes are generally 10 to 24 times as massive as the Sun. Astronomers spot them when another star draws near enough for some of the matter surrounding it to be snared by the black hole's gravity, churning out x-rays in the process. Most stellar black holes, however, are very difficult to detect. Judging from the number of stars large enough to produce such black holes, however, scientists estimate that there are as many as ten million to a billion such black holes in the Milky Way alone.
On the other end of the size spectrum are the giants known as "supermassive" black holes, which are millions, if not billions, of times as massive as the Sun. Astronomers believe that supermassive black holes lie at the center of virtually all large galaxies, even our own Milky Way. Astronomers can detect them by watching for their effects on nearby stars and gas.

Historically, astronomers have long believed that no mid-sized black holes exist. However, recent evidence from Chandra, XMM-Newton and Hubble strengthens the case that mid-size black holes do exist. One possible mechanism for the formation of supermassive black holes involves a chain reaction of collisions of stars in compact star clusters that results in the buildup of extremely massive stars, which then collapse to form intermediate-mass black holes. The star clusters then sink to the center of the galaxy, where the intermediate-mass black holes merge to form a supermassive black hole.

Please be respectful of copyright. Unauthorized use is prohibited.
Please be respectful of copyright. Unauthorized use is prohibited.
Please be respectful of copyright. Unauthorized use is prohibited.
Please be respectful of copyright. Unauthorized use is prohibited.
Please be respectful of copyright. Unauthorized use is prohibited.
A view of the central region of the Perseus galaxy cluster, one of the most massive objects in the universe, shows the effects that a relatively small but supermassive black hole can have millions of miles beyond its core. Astronomers studying this photo, taken by the Chandra X-ray Observatory, determined that sound waves emitted by explosive venting around the black hole are heating the surrounding area and inhibiting star growth some 300,000 light-years away. "In relative terms, it is as if a heat source the size of a fingernail affects the behavior of a region the size of Earth," said Andrew Fabian of Cambridge University.

At the center of our galaxy, a supermassive black hole churns. Learn about the types of black holes, how they form, and how scientists discovered these invisible, yet extraordinary objects in our universe.
Interbreeding between animals of different lineages is widespread in nature—and may reveal some of the mysteries of evolution.
Following the crop cycles in California and Mexico, generations of Mexican farmworkers have migrated back and forth to provide for their families.
Ancient fortified towns, Roman ruins, and Sahara sands make Africa’s largest country an undiscovered tourism giant hiding in plain sight.
As rivers either rage or fade from climate change-caused extreme weather, the debate is intensifying as to what role dams should or shouldn’t play in managing it.
A glimmer of hope for one of the world's rarest penguins
American bison all have some cattle DNA. Here’s why.
See the year's best wildlife photos
How animals hybrids happen, from ligers to zorses
Why these seabirds stage a rowdy springtime love-in
Tuberculosis is killing this zoo's lemurs—but it hasn't closed
Once devastated, these Pacific reefs have seen an amazing rebirth
Is building more dams the way to save rivers?
4 easy ways to make your holidays more eco-friendly
Melting mountain peaks could kill thousands. Can science help?
Protecting Canada’s wetland wonders
Why this German bunker is full of blood and urine
A German werewolf's 'confessions' horrified 1500s Europe
How Mussolini led Italy to fascism—and why his legacy looms today
Why Diwali is India’s most important holiday
Did these 5 leaders’ legendary achievements happen?
These families lead double lives across the U.S.-Mexico border
The Tower of London has terrified people for nearly 1,000 years
Dinosaur ‘mummy’ reveals a surprisingly hoof-like foot
NASA surprised itself with its asteroid-smashing success
Striking pictures reveal the microscopic world’s hidden wonders
Speakers of rare languages struggled to navigate COVID care
How Fido evolved to have those irresistible puppy-dog eyes
230-million-year-old mystery fossil hints at pterosaurs’ origins
Cruises on the Great Lakes are giving new life to the Rust Belt
Memories are crafted in wool in this tiny Russian republic
Is Algeria the next great travel destination in Africa?
Australia’s newest national parks will be Indigenous-managed
Italy’s last wild steppe is seeing a renaissance
Uncover hidden
Nurse Handjob Porn
High Heels Crossing Legs
Red Hair Porn Actress

Black Hole

Report Page