Universe

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Q: What is the Friedmann universe theory?

    A: In 1922, Russian mathematician Alexander Friedmann answered Albert Einstein's equations of general relativity. Friedmann's answers led to the theory that the universe is dynamic, meaning that it changes in size over time. Friedmann introduced the term "expanding universe" into the scientific lexicon.
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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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  • 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: Why can't we see past the cosmological horizon?

    A: It's impossible to look beyond the cosmological horizon because this horizon represents the distance that light has traveled since the big bang. The cosmological horizon exists because the speed of light is constant and all electromagnetic waves travel at the same speed. Therefore, the cosmological horizon holds for visible light as well as for other types of waves, such as radio or microwaves.
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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: 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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  • 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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  • 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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  • How many solar systems are there?

    Q: How many solar systems are there?

    A: The exact number of solar systems is not known. According to NASA, there are more than 100 billion galaxies within the universe. One of these galaxies is the Milky Way galaxy, where our solar system is located.
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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: Does the universe end?

    A: Scientists believe the Universe is infinitely large and does not end. However, only part of the Universe is visible from Earth. The Observable Universe is a sphere around the Earth, and anything beyond this sphere cannot be observed from Earth because of continuing expansion over a long period of time.
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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: 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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