Category: ask

Explica um pouco sobre buracos negros

Explica um pouco sobre buracos negros

De acordo com a Teoria da Relatividade Geral, um buraco negro é uma região do espaço da qual nada, nem mesmo partículas que se movem na velocidade da luz, podem escapar.

Este é o resultado da deformação do espaço-tempo, causada após o colapso gravitacional de uma estrela, com uma matéria astronomicamente maciça e, ao mesmo tempo, infinitamente compacta e que, logo depois, desaparecerá dando lugar ao que a Física chama de singularidade, o coração de um buraco negro, onde o tempo para e o espaço deixa de existir

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. Um buraco negro começa a partir de uma superfície denominada horizonte de eventos, que marca a região a partir da qual não se pode mais voltar. 

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O adjetivo negro em buraco negro se deve ao fato de este não refletir a nenhuma parte da luz que venha atingir seu horizonte de eventos, atuando assim como se fosse um corpo negro perfeito em termodinâmica.

Buracos negros não emitem luz, a luz observados são observados do disco de acreção ao redor do buraco negro (disco de poeira e gás que chegam a milhões e milhões de graus e que emitem principalmente raio x).

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De acordo com a teoria, pode haver três tipos de buracos negros: buracos negros estelares, supermassivos e em miniatura – dependendo da sua massa. Esses buracos negros se formariam de maneiras diferentes.

Buracos negros estelares formam-se quando uma estrela maciça colapsa.

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Os buracos negros supermassivos, que podem ter uma massa equivalente a bilhões de sóis, provavelmente existem nos centros da maioria das galáxias, incluindo nossa própria galáxia, a Via Láctea. 

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Os astrônomos não sabem exatamente como os buracos negros supermassivos se formam, mas é provável que eles sejam um subproduto da formação da galáxia. Devido à sua localização nos centros de galáxias, perto de muitas estrelas bem embaladas e nuvens de gás, os buracos negros supermassivos continuam a crescer em uma dieta constante de matéria.

Ninguém jamais descobriu um buraco negro em miniatura (ou micro buraco negro), que teria uma massa muito menor do que a do nosso Sol. Mas é possível que os buracos negros em miniatura possam ter se formado pouco depois do “Big Bang”, que se pensa ter começado o universo há 13,7 bilhões de anos. Muito cedo na vida do universo, a rápida expansão de alguma questão poderia ter comprimido a matéria que se movia mais devagar o suficiente para se contrair em buracos negros.

Outra divisão separa os buracos negros que giram (possuem momento angular) daqueles que não giram.

E também há buracos negros de massa intermediária, que teriam massa entre os buracos negros estelares e supermassivos. (alguns milhares de massas solares)

Você pode encontrar mais posts sobre buracos negros AQUI, porem está em inglês.

Can u post pics of earth 🌍

Can u post pics of earth 🌍

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The Blue Marble—Earth as seen by Apollo 17 in 1972

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This incredible image of the Earth rise was taken during lunar orbit by the Apollo 11 mission crew in July of 1969. The first manned lunar mission, Apollo 11 launched aboard a Saturn V launch vehicle from the Kennedy Space Center, Florida on July 16, 1969 and safely returned to Earth on July 24, 1969.

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This image taken by an astronaut aboard Space Shuttle mission STS-103 shows a panoramic view of Earth at moonrise.

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In this rare image taken on July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft has captured Saturn’s rings and our planet Earth and its moon in the same frame.

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Earth as seen by Apollo 11 astronauts at the beginning of the third day of TLC

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A view of the Apollo 11 lunar module “Eagle” as it returned from the surface of the moon to dock with the command module “Columbia”. A smooth mare area is visible on the Moon below and a half-illuminated Earth hangs over the horizon. The lunar module ascent stage was about 4 meters across. Command module pilot Michael Collins took this picture just before docking at 21:34:00 UT (5:34 p.m. EDT) 21 July 1969.

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This panorama featuring Earth’s horizon and clouds over the South Pacific Ocean, complemented with a “tiny” distant moon (upper right), was photographed by one of the Expedition 36 crew members aboard the International Space Station.

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The Sun from the Internation Space Station

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images: NASA/JPL

To see more images and posts about the Earth click here.

Do you have any fun facts about magnetars?

Do you have any fun facts about magnetars?

  • A magnetar is a type of neutron star with an extremely powerful magnetic field. 
  • The theory regarding these objects was proposed by Robert Duncan and Christopher Thompson in 1992, but the first recorded burst of gamma rays thought to have been from a magnetar had been detected on March 5, 1979. During the following decade, the magnetar hypothesis became widely accepted as a likely explanation for soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs).

  • The magnetic field decay powers the emission of high-energyelectromagnetic radiation, particularly X-rays and gamma rays.

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  • Like other neutron stars, magnetars are around 20 kilometres (12 mi) in diameter and have a mass 2–3 times that of the Sun. 

  • Magnetars are differentiated from other neutron stars by having even stronger magnetic fields, and rotating comparatively slowly, with most magnetars completing a rotation once every one to ten seconds, compared to less than one second for a typical neutron star. This magnetic field gives rise to very strong and characteristic bursts of X-rays and gamma rays.

    The active life of a magnetar is short. Their strong magnetic fields decay after about 10,000 years, after which activity and strong X-ray emission cease. Given the number of magnetars observable today, one estimate puts the number of inactive magnetars in the Milky Way at 30 million or more.

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  • Magnetars are characterized by their extremely powerful magnetic fields of 108 to 1011 tesla. These magnetic fields are hundreds of millions of times stronger than any man-made magnet, and quadrillions of times more powerful than the field surrounding Earth. Earth has a geomagnetic field of 30–60 microteslas, and a neodymium-based, rare-earth magnet has a field of about 1.25 tesla, with a magnetic energy density of 4.0×105 J/m3. A magnetar’s 1010 tesla field, by contrast, has an energy density of 4.0×1025 J/m3, with an E/c2 mass density >104 times that of lead. The magnetic field of a magnetar would be lethal even at a distance of 1000 km due to the strong magnetic field distorting the electron clouds of the subject’s constituent atoms, rendering the chemistry of life impossible. At a distance of halfway from Earth to the moon, a magnetar could strip information from the magnetic stripes of all credit cards on Earth. As of 2010, they are the most powerful magnetic objects detected throughout the universe.

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As of March 2016, 23 magnetars are known, with six more candidates awaiting confirmation.

Images:

ESA/ATG medialab

can you show me close ups of Neptune, btw i lo…

can you show me close ups of Neptune, btw i love your account❤

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This picture of Neptune was produced from the last whole planet images taken through the green and orange filters on NASA’s Voyager 2 narrow angle camera. The images were taken at a range of 4.4 million miles from the planet, 4 days and 20 hours before closest approach.

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During August 16 and 17, 1989, the Voyager 2 narrow-angle camera was used to photograph Neptune almost continuously, recording approximately two and one-half rotations of the planet.

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Assembled using orange, green, and blue filtered images taken by Voyager 2 on August 24 1989.

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Based on the images recorded during its close encounter and in the following days, this inspired composited scene covers the dim outer planet, largest moon Triton, and faint system of rings.

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NASA’s Voyager 2 high resolution color image, taken 2 hours before closest approach, provides obvious evidence of vertical relief in Neptune’s bright cloud streaks. These clouds were observed at a latitude of 29 degrees north near Neptune’s east terminator.

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Assembled using orange, green, and blue filtered images taken by Voyager 2 on August 31 1989.

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Neptune and triton captured by Voyager 2 on their way out of the solar system in August 1989.

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Neptune and triton captured by Voyager 2 on their way out of the solar system in August 1989.

This view of Despina eclipsing and transiting Neptune is composed of four frames captured nine minutes apart on August 24, 1989 from 20:00 to 20:27 through blue, orange, violet, and green filters. In this version, Despina has been brighted substantially to make it easier to spot.

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This crescent view of the outermost planet and its moon is one of the last images recorded by Voyager 2’s cameras as it sped onwards to interstellar space, having surveyed most of the outer Solar System. 

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Arcs in the Adams ring (left to right: Fraternité, Égalité, Liberté), plus the Le Verrier ring on the inside

Images: NASA/JPL Kevin Gill

To learn more, click here.

What do you find most interesting about Uranus…

What do you find most interesting about Uranus? And some of its moons?

Uranus is a very incredible planet. Perhaps what draws the most attention is the fact that it spins “ lying down ”.

  • Uranus was officially discovered by Sir William Herschel in 1781. 
  • Uranus turns on its axis once every 17 hours, 14 minutes.

  • Uranus makes one trip around the Sun every 84 Earth years.

  • Only one spacecraft has flown by Uranus.

  • Uranus has an atmosphere which is mostly made up of hydrogen (H2) and helium (He), with a small amount of methane (CH4). 

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Uranus has 13 known rings. The inner rings are narrow and dark and the outer rings are brightly colored.

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Uranus has 27 moons. Uranus’ moons are named after characters from the works of William Shakespeare and Alexander Pope.

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The five largest satellites of Uranus are: Oberon, Titania, Umbriel, Ariel and Miranda.

An interesting thing is that some of the moons of Uranus are on a collision route, and could collide in a few million years. There may be a collision between Cressida and Desdemona, and also the collision between Cupid and Belinda, but these moons have irregular shapes and are very small compared to our moon.

Images: NASA/JPL/Keck Observatory

What are white holes? Is there any other kinds of “holes” in the universe?

Well, black holes were predicted by Einstein’s theory of relativity and actually discovered over the…

Hallo! So, my professor asked us to do a presentation about any topic we might find interesting, more like a ”random-cool-facts-thing”. Astronomy is becoming one of my special interests so I thought I could talk about it. Do you have any suggestions for topics that you find super cool and that most people don’t know about? Thank you :)

Hello, astronomy is full of cool stuff, there are lots of things you can talk about. You can talk…

Why’s space black instead of pink?

●﹏● OK, let’s go. First, in relation to pink color, this depends on where the starlight would…

where do you start when self teaching yourself astronomy? it’s always been something i’ve been interested in but could never figure out where to start. thanks!

There are many books for beginners and some for people who know a little more about astronomy. There…

Então me recomenda os livros que vc leu em português pq eu quero muito. Pode ser de física, astrofísica, astronomia, e qualquer coisa que tenha a ver com o espaço por favor e obrigado

Ok, aqui está alguns livros que eu li:Albert Einstein e as fronteiras da físcia [Jeremy…