Planets

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The discovery that the Earth is round is most commonly ascribed to the ancient Greek philosopher Pythagoras, while the credit for proving it is usually given to Aristotle. It appears that most ancient Greek philosophers that followed him believed in a round Earth. Since the records from that time are not perfect, it is quite possible that someone before him was aware of the Earth's round shape.

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  • When Was Mars Discovered?

    Q: When Was Mars Discovered?

    A: While no specific date can be identified for the discovery of Mars, knowledge of the planet dates back to ancient civilizations. Ancient Romans, Egyptians and Chinese astronomers independently discovered and named the planet.
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  • Who Discovered That the Earth Was Round?

    Q: Who Discovered That the Earth Was Round?

    A: The discovery that the Earth is round is most commonly ascribed to the ancient Greek philosopher Pythagoras, while the credit for proving it is usually given to Aristotle. It appears that most ancient Greek philosophers that followed him believed in a round Earth. Since the records from that time are not perfect, it is quite possible that someone before him was aware of the Earth's round shape.
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  • How Far Away Is Saturn From the Sun?

    Q: How Far Away Is Saturn From the Sun?

    A: Saturn is an average of 886 million miles from the sun, which puts it about 9.5 times farther away from the sun than the Earth. The exact distance from Saturn to the sun varies based on Saturn's location along its elliptical orbit.
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  • How Did Saturn Form?

    Q: How Did Saturn Form?

    A: Saturn formed according to one of two models: the core accretion model, which states that planets formed over time through gravitational forces drawing materials together, or the disk instability model, which states that clumps of dust and gas fused together quickly and progressively formed a planet.
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  • How Long Does It Take the Earth to Make One Revolution?

    Q: How Long Does It Take the Earth to Make One Revolution?

    A: Earth completes one revolution around the Sun for every 365.242199 times it rotates on its axis. This figure is, unfortunately, not evenly divisible, which has historically caused difficulties for the creators of various calendars.
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  • How Much Does Saturn Weigh?

    Q: How Much Does Saturn Weigh?

    A: Because weight is calculated based on gravitational pull, it is impractical to determine the weight of a planet. For example, an object weighing 500 pounds on Earth weighs 465 pounds on Saturn because of the planets' different gravitational pulls. Thus, planets are compared by calculating their mass, which remains constant.
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  • Which Two Planets Are the Only Ones in the Solar System to Have No Moons?

    Q: Which Two Planets Are the Only Ones in the Solar System to Have No Moons?

    A: Mercury and Venus are the two planets in the solar system without any moons. This is likely due to the close proximity of both planets to the sun.
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  • Where Is Mars Located?

    Q: Where Is Mars Located?

    A: Mars is the fourth planet from the sun. Its average distance from the sun is 141,633,120 miles, approximately 1.5 times that of Earth.
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  • How Can You Memorize the Order of the Planets?

    Q: How Can You Memorize the Order of the Planets?

    A: A popular way to memorize the order of the planets is to use a mnemonic device, such as "My Very Educated Mother Just Served Us Nachos," as suggested by the International Astronomical Union. "My" is Mercury, "Very" is Venus, "Educated" is Earth, "Mother" is Mars, "Just" is Jupiter, "Served" is Saturn, "Us" is Uranus and "Nachos" is Neptune.
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  • What Planet Is the "third Rock From the Sun"?

    Q: What Planet Is the "third Rock From the Sun"?

    A: Earth is considered to be the "third rock from the sun." That phrasing is used because Earth is the third planet from the sun, as well as being a terrestrial (rocky) planet.
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  • How Much Would a 100 Pound Person Weigh on Neptune?

    Q: How Much Would a 100 Pound Person Weigh on Neptune?

    A: A 100-pound person who stood, or floated, on the surface of Neptune would weigh 114 pounds. Although Neptune is much more massive than Earth, it's far less dense, so the acceleration of gravity at its surface is weaker than expected for a planet that is 17 times Earth's mass.
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  • What Is the Difference Between a Planet and a Star?

    Q: What Is the Difference Between a Planet and a Star?

    A: Planets and stars differ in their mass, composition and life cycle. Stars are usually structurally simple bodies of high mass that produce energy by way of nuclear fusion of hydrogen into helium. Planets are much smaller, do not generate light and usually orbit stars.
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  • What Is the Weather Like on Jupiter?

    Q: What Is the Weather Like on Jupiter?

    A: Jupiter has a dry, thick atmosphere; high-speed winds, turbulence and long-lasting storms are common. The weather on Jupiter is much different from that found on a rocky planet such as the Earth.
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  • What Are the Nine Planets in Order?

    Q: What Are the Nine Planets in Order?

    A: The nine planets in order are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and, if it's still considered the ninth planet, Pluto. However, not only has Pluto been demoted to a dwarf planet by some astronomers, but its orbit is so eccentric that there are times when it's closer to the sun than Neptune.
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  • What Are the Nicknames for the Planets?

    Q: What Are the Nicknames for the Planets?

    A: Nicknames for the eight planets in the solar system are Swift Planet for Mercury, Morning Star and Evening Star for Venus, Blue Planet for Earth, Red Planet for Mars, Giant Planet for Jupiter, Ringed Planet for Saturn, Ice Giant for Uranus and Big Blue Planet for Neptune. Pluto was once considered a planet and had the nickname Ice Planet, but it is now classified as a dwarf planet.
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  • What Type of Planet Is Earth?

    Q: What Type of Planet Is Earth?

    A: According to Encyclopædia Britannica, Earth is classified as a terrestrial planet. A terrestrial planet is rocky, in contrast to the predominantly gas planets found in the outer solar system.
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  • How Did Neptune Get Its Name?

    Q: How Did Neptune Get Its Name?

    A: Neptune was given its name by its discoverer, Urbain Le Verrier. Honoring the tradition of naming planets after Roman gods, Le Verrier chose Neptune, who was the Roman sea god. He chose this name because of the blue colors that dominate the planet.
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  • What Causes Earth's Magnetic Field?

    Q: What Causes Earth's Magnetic Field?

    A: The leading hypothesis is that the earth’s spinning core causes the Earth's magnetic field, but scientists are unsure about the exact mechanism by which it is created. Iron is the primary constituent of the Earth’s core, and it is able to spin because of its layered construction.
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  • Who Named Saturn?

    Q: Who Named Saturn?

    A: Saturn has been observed with the naked eye since prehistoric times, so it is not possible to know who named it first. Roman astronomers named it Saturnus after their god of agriculture and the father of Jove, which translates to Saturn in English.
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  • What Is a Dwarf Planet?

    Q: What Is a Dwarf Planet?

    A: A dwarf planet is a celestial body that orbits the sun and is large enough to assume a round shape but has not cleared its orbital path of similar objects. There are five known dwarf planets as of 2014: Pluto, Ceres, Eris, Haumea and Makemake.
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  • What Are the Names of Mercury's Moons?

    Q: What Are the Names of Mercury's Moons?

    A: There are no names for Mercury's moons because the planet does not have any moons. The only other planet that has no moons is Venus.
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