Universe

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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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  • 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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  • 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 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 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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  • 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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  • 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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  • 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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  • Q: What is believed to be the origin of giant elliptical galaxies?

    A: Giant elliptical galaxies form early in the life of local galactic clusters as members of the group pass close by each other and begin to merge, according to John Dubinski for the Canadian Institute for Theoretical Astrophysics. In any sizable galactic cluster, some galaxies near the core of the group gravitationally interact with each other, exchange material and eventually fall together to form the core of the central elliptical giant.
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  • Q: How many atoms are in the universe?

    A: In the observable universe, scientists estimate that there are possibly 10 quadrillion vigintillion and 100,000 quadrillion vigintillion atoms, according to Universe Today. The number of atoms in the universe beyond what is known is not calculable.
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  • Q: Who disproved the Ptolemaic theory of the universe?

    A: Nicolaus Copernicus' 16th-century assertion that the Ptolemaic theory of the solar system was wrong was considered revolutionary. However, his published findings in 1514 weren't widely accepted because his studies were based on naked-eye observations. Galileo Galilei used a telescope to disprove the Earth-centered solar system.
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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 Ptolemy's universe theory?

    A: Greek philosopher Claudius Ptolemy believed that the sun, planets and stars all revolved around the Earth. This belief gave way to the ancient Greek theory of a geocentric or Ptolemaic model of the universe. "Geocentric" refers to the belief that the Earth is the center of the universe.
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  • Q: How big is space?

    A: As far as humans can tell, space is infinite; it has no end or borders. Scientists believe that space will always seem infinite to humans for two reasons. First, our investigation of space has never found an edge (or any indications of an edge). Second, measurements show that space is expanding faster and faster, which pushes the edges of the universe ? if there are any ? ever farther out.
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  • Q: What is the best estimate scientists have made of the physical size of the universe?

    A: The best estimate of scientists trying to quantify the size of the universe place estimates on the observable portion at 46 billion light years from earth to the observable edge, or approximately 91 billion light years in diameter. However, there are some fundamental flaws with this approach.
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  • Q: How did the universe begin?

    A: The universe began with the Big Bang around 13.6 billion years ago. The Big Bang was a rapid expansion of the universe from a tiny single point. This hot expansion has continued since then, resulting in the expansion of the universe in every direction.
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  • Q: Is the universe flat?

    A: As of 2014, the universe is believed to be flat, according to the inflationary theory. This theory has to do with the density of the universe and suggests that the universe must be flat as piece of paper.
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  • Q: What is diurnal motion?

    A: In astronomy, the term "diurnal motion" refers to the movement of stars around the Earth's celestial poles due to the planet's rotation on its axis. This movement is called a diurnal circle.
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  • Q: What is the ultimate fate of an open universe?

    A: Although the ultimate fate of the universe is a largely debated topic, according to the University of Tennessee, in an open universe the universe will continue to expand forever. This is due to insufficient mass to cause the expansion to stop.
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  • How many solar systems are there in the universe?

    Q: How many solar systems are there in the universe?

    A: There are billions of stars, and no one knows how many solar systems there are. The Earth's galaxy, the Milky Way, is so large that it would take an object 100,000 years to cross it traveling at the speed of light.
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  • Q: How far is the edge of space from Earth?

    A: The edge of space is generally recognized internationally to be at the Kármán Line, which is 62 miles from the surface of Earth. While the exact boundary of space is open to interpretation, this is the definition recognized by the Federation Aeronautique Internationale and National Aeronautics and Space Administration.
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