Universe

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According to NASA, the temperature of a black hole with the mass of the sun is only one ten-millionth of a degree over absolute zero. Scientists determine this by measuring the temperature of the radiation that comes from a black hole.

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  • Why did people once believe that Earth was the center of the Universe?

    Q: Why did people once believe that Earth was the center of the Universe?

    A: The belief of early astronomers that the Earth was the center of the universe stemmed from limited astronomical tools and geocentric attitudes. The Ptolemaic Model, developed around 100 A.D., presented the Earth-centered solar system in which most early Roman astronomers believed.
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  • Who discovered the planet Saturn?

    Q: Who discovered the planet Saturn?

    A: It is impossible to determine who discovered Saturn, as it is one of five planets that are visible without the aid of instruments. Saturn has been widely observed by people for thousands of years, although its unique and complex system of rings are only visible using a telescope.
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  • What are some facts about the Aurora Borealis?

    Q: What are some facts about the Aurora Borealis?

    A: Aurora Borealis occurs when materials from the surface of the Sun collide with the atmosphere of the Earth. Experts make predictions about the occurrence of Aurora Borealis based on events taking place on the Sun and the speed of matter being thrown from the Sun's surface. Aurora Borealis is visible in portions of the Northern Hemisphere, including Canada, Scandinavia, North America, Siberia and Northern Europe.
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  • Why do some stars appear brighter than others?

    Q: Why do some stars appear brighter than others?

    A: The apparent brightness of a star viewed from Earth varies based both on the type of star and its distance from the planet. The apparent magnitude differs from a star's absolute magnitude, which describes its brightness from a set distance, rather than the varying distances of stars seen from Earth. The lower the apparent magnitude, the brighter the star is as seen from Earth.
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  • What is the temperature of a black hole?

    Q: What is the temperature of a black hole?

    A: According to NASA, the temperature of a black hole with the mass of the sun is only one ten-millionth of a degree over absolute zero. Scientists determine this by measuring the temperature of the radiation that comes from a black hole.
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  • How many modern constellations are there?

    Q: How many modern constellations are there?

    A: As of 2014, there are 41 modern constellations, which are constellations added to the catalogue after 1600. Four of them, Carina, Puppis, Pyxis and Vela are derived from Argo, a constellation catalogued by Ptolemy.
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  • What happens after a supernova?

    Q: What happens after a supernova?

    A: Depending on the size of the star before it explodes as a supernova, the core of the star either shrinks back into a tiny neutron star or becomes a black hole. If the star is only a few times bigger than the sun, the core becomes a tiny neutron star. If the star is much bigger than the sun, the chances of it becoming a black hole are much greater.
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  • Do the planets travel around the sun in a path called an orbit?

    Q: Do the planets travel around the sun in a path called an orbit?

    A: Planets travel around the sun in paths called orbits. Each planet has its own orbit around the sun, and one orbit around the sun is called a year. All planets travel in the same direction around the sun.
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  • What does NASA say about galactic alignment?

    Q: What does NASA say about galactic alignment?

    A: According to NASA, the sun aligns with the center of the Milky Way galaxy as compared to the Earth every December when the sun enters Sagittarius. Doomsday predictions about the winter solstice of December 2012 revolved around the alignment of the sun, Earth and the galactic center. The sun and moon tug on the planet more than the galactic center, so galactic alignment does not alter the Earth whatsoever.
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  • Q: What is Kepler's Universe Theory?

    A: Johannes Kepler's theories of the universe were notable for hypothesizing that the universe was created on April 27, 4977 B.C. and that the planets orbit in an elliptical pattern rather than a circular pattern. His theory superseded previous theories which postulated that planets move in circular orbits at constant speeds.
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  • Q: What are the differences between the solar system and the Milky Way Galaxy?

    A: The solar system is a system in the universe that is comprised of the Sun, eight official planets, three dwarf planets and approximately 130 satellites of the planets, according to Nine Planets. Besides these bodies, the solar system also has numerous comets and asteroids, which are smaller. On the other hand, the Milky Way is the galaxy within which the solar system falls.
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  • Q: What is Galileo Galilei famous for?

    A: Galileo Galilei is famous for his physics-related and astronomy-related observations. He built his own telescope in 1609 and used it to study the cosmos, eventually concluding that Earth’s solar system is heliocentric. Galileo’s theories on motion were later used as the foundation of Isaac Newton’s work.
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  • Q: What are some world facts?

    A: Observed from space, the United States is the brightest country on the brightest planet in the Solar System because Earth's water makes it the brightest planet and the United States is abundant in artificial lighting, especially at night. Russia is the largest country in the world, Vatican City is the smallest country, and 39 million Vatican Cities could fit inside Russia. In 2011, the global population topped 7 billion people and is expected to reach 10.5 billion by 2050.
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  • Q: What is the nature of the universe?

    A: The nature of the universe can be described by universal and absolute physical laws. There are numerous laws that govern the universe, such as the laws of mechanics, thermodynamics, gases, conservation and relativity.
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  • What color is the universe?

    Q: What color is the universe?

    A: When gazing at the starry night sky, you might imagine that the color of the universe is a dark shade of midnight blue. However, the average color is much brighter than that. When all of the universe’s light is averaged together, the resulting color is a much less mysterious light beige.
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  • Q: Is the universe expanding?

    A: The universe has been known to be expanding since 1929, when Edwin Hubble measured the speed at which distant galaxies appear to be receding from Earth's position in space. In the early 21st century, astronomers measured the rate of expansion and discovered that it is increasing.
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  • Q: What is the current temperature of the universe?

    A: By taking measurements of background microwave radiation, scientists have been able to establish that the average temperature of the universe is just over 2.7 degrees Kelvin. This means that the average temperature of space is just below negative 450 degrees Fahrenheit.
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  • Q: How does gravity hold the universe together?

    A: Gravity holds the universe together by keeping the large bodies that make up the universe together. It keeps the Earth in orbit around the sun, the sun in orbit around the center of the Milky Way and the Milky Way bound to other nearby galaxies known as the Local Group.
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  • Q: How do you explain the nebular theory?

    A: The nebular theory of solar system formation suggests that stars and their planets form out of cooling interstellar clouds of molecular hydrogen. As the cloud contracts, it forms a disc of dense material that forms the star. As it forms, the star throws off material that coalesces into planets.
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  • Q: What are Edgar Cayce's thoughts on black holes?

    A: The writings and revelations of Edgar Cayce may be mute on the topic of black holes specifically, but he does refer to what he terms "the outer darkness," a region devoid of light, love and life that some may encounter at the time of death. Cayce's description of the outer darkness, denser in its center than at its outer edges, resemble some characteristics of the present-day understanding of black holes.
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  • Q: Why is outer space dark?

    A: Outer space appears dark at night for multiple reasons, the most simple being that the nearest light source, the sun, is blocked by the earth, creating darkness. Outside Earth's atmosphere, outer space appears dark instead of blue because the sun's light is not refracted by atmospheric gases.
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