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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  • 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 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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  • 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 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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  • 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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  • 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 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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  • Q: How Do You Know the World Might Be Ending?

    A: Scientists postulate that the end of the world could stem from a variety of sources, including destruction by meteor, overpopulation and war that affects the entire globe. Dysgenics, or the possible decay of human genes, nuclear warfare and climate change are other scenarios that scientists study and that may predict the end of the human species. Although some scenarios include the end of both the planet and the human race, others suggest that the planet and other forms of life are likely to continue to exist following the extinction of humans. A global pandemic, possibly due to a virus or an antibiotic-resistant bacteria, is thought to be the only cause of extinction that would affect humans alone.
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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: Who Discovered the First Black Hole?

    A: In science, if something isn't directly observable it can't be "discovered." There is only indirect evidence of black holes. The existence of black holes has been a topic of speculation for hundreds of years, but John Wheeler is credited with coining the term, "black hole," in 1969.
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  • Q: How Big Is the Universe?

    A: As of 2013, the National Aeronautics and Space Administration determined, with a margin of error of only 0.4 percent, that the universe is infinite in size. The observable universe extends 92 billion light years in diameter. The exact size of the universe, or if there are multiples, is unknown.
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  • Q: Where Was the Sun in Ptolemy's Model of the Universe?

    A: Ptolemy's model of the universe was geocentric, containing the Earth at the center with a series of circles, called deferents, moving outward from the Earth, containing the moon, Mercury, Venus, the sun, Mars, Jupiter and Saturn. Ptolemy placed fixed stars and the Primum Mobile in the spheres after Saturn.
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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: 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: 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 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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  • Q: What Is Gravitational Attraction?

    A: Gravitational attraction is the force that draws two objects together. It is governed by the law of universal gravitation, which states that the force of attraction between two objects is related to the mass of the objects and inversely related to the distance between the two.
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  • Q: What Is the No Boundary Universe Theory?

    A: The no boundary theory of the universe likens the universe to the Earth, in that is impossible to find any boundaries traveling around the Earth or to fall off it. This is possible as a result of theorizing that prior to the Big Bang, the generally accepted laws of physics did not apply and that the concept of time as we know it did not exist.
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  • Q: How Do Black Holes Form?

    A: Universe Today explains that black holes are the result of objects collapsing under the force of gravity until the acceleration needed to escape from them exceeds the speed of light. Any object can, in principle, become a black hole if it collapses to sufficient density. They can also be formed from two neutron stars colliding together. According to Universe Today, there are supermassive black holes in every galaxy.
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  • Q: Did the Idea of a Heliocentric View of the Solar System Originate With Copernicus?

    A: The ancient Greek astronomer and mathematician known as Aristarchus of Samos was the first person to propose a heliocentric view of the solar system. He lived circa 310 B.C. to 230 B.C. and stated that the Earth, like other planets, orbited the sun, which he regarded as the universe's center.
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