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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  • What Is the Atmosphere Like on Mars?

    Q: What Is the Atmosphere Like on Mars?

    A: According to Space.com, the atmosphere on Mars is around 100 times thinner compared to that of the Earth's and is composed of about 95 percent carbon dioxide. However, the Martian atmosphere is still thick enough to sustain weather, winds and clouds.
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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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  • Can Mars Sustain Life?

    Q: Can Mars Sustain Life?

    A: According to NASA, 7 billion years ago, Mars may have been an excellent place for microbes to live, but currently it cannot support life because the air is too thin and is comprised mainly of carbon dioxide. After drilling into the rocks on Mars, scientists discovered the key ingredients of life, including sulfur, nitrogen, hydrogen, oxygen and carbon.
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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 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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  • What Is the Composition of Mars' Atmosphere?

    Q: What Is the Composition of Mars' Atmosphere?

    A: The composition of Mars' atmosphere is 95.32 percent carbon dioxide, 2.7 percent nitrogen, 1.6 percent oxygen and 0.08 percent carbon monoxide. The remaining 0.3 percent is made up of various trace elements.
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  • What Is the Earth's Motion That Causes Day and Night?

    Q: What Is the Earth's Motion That Causes Day and Night?

    A: The spinning and rotating movement of the earth along its vertical axis causes the difference between day and night. The differences between light and darkness on the earth's surface are caused primarily by the earth’s rotation along a vertical axis. This constant spinning motion accounts for hourly changes in light and produces long-term changes in daylight hours through the seasons.
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  • How Is Earth Different From Other Planets?

    Q: How Is Earth Different From Other Planets?

    A: Earth is unique in that scientists have found the planet to be the only one to have liquid water on its surface, intelligent life forms living on it, a moon that helps regulate surface temperatures, an atmosphere with 21 percent oxygen and plate tectonics, according to Space.com. Scientists believe Earth exists in a "Goldilocks zone" where conditions are just right to support life.
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  • What Is the Length of a Day and Year on Saturn?

    Q: What Is the Length of a Day and Year on Saturn?

    A: A day on Saturn is 10.7 hours, and a year is equivalent to 29 Earth years or 10,832 days. The length of the day is calculated from the planet's rotational speed, while scientists determine the length of a year by observing Saturn's orbit.
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  • What Is the Fastest Moving Planet in the Solar System?

    Q: What Is the Fastest Moving Planet in the Solar System?

    A: The fastest-moving planet in the solar system is Mercury. The planet whizzes around the sun at an orbital velocity of 1.6 times that of Earth's orbital velocity. This amounts to 107,700 miles per hour.
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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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  • When Did Pluto Become a Dwarf Planet?

    Q: When Did Pluto Become a Dwarf Planet?

    A: Pluto became a dwarf planet in 2006. Upon being stripped of its title as a planet, Pluto joined two other celestial bodies, called Eris and Ceres, in the category of dwarf planets. The decision to reclassify the former planet was made by the International Astronomical Union (IAU).
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  • Where Is Mars Located in the Sky?

    Q: Where Is Mars Located in the Sky?

    A: Mars is the fourth planet from the sun and the seventh largest at 227,940,000 kilometers, according to the University of Central Florida. The size and close proximity of Mars render it visible in the night sky, especially at certain points during its orbit.
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  • Where Is the Highest Temperature on Jupiter?

    Q: Where Is the Highest Temperature on Jupiter?

    A: The highest temperatures on Jupiter are found in its core and are estimated at over 60,000 degrees Fahrenheit. Due to Jupiter's distance from the Sun, most of its heat comes from its core, and the temperature generally decreases moving away from the planet's center.
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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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  • 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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  • How Long Does It Take the Earth to Complete an Orbit Around the Sun?

    Q: How Long Does It Take the Earth to Complete an Orbit Around the Sun?

    A: It takes roughly 365 days, or 1 year, for the Earth to complete its orbit around the Sun. Although it is an elliptical orbit, it is almost circular, so there is only a slight difference between the closest and farthest points from the Sun throughout the orbit. The two-dimensional plane occupied by the Earth's orbit is called the ecliptic.
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  • What Are Some Cool Facts About Mars?

    Q: What Are Some Cool Facts About Mars?

    A: Mars, the fourth planet from the sun, has interested people for thousands of years, according to BBC News. However, whereas the people of ancient Greece and Rome found Mars fascinating for its red color, people today are more interested in finding water on the planet.
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  • What Is the Average Surface Temperature of Neptune?

    Q: What Is the Average Surface Temperature of Neptune?

    A: The average surface temperature on Neptune is minus 329.8 degrees Fahrenheit, close to its effective temperature of minus 353 degrees Fahrenheit. Neptune is among the coldest planets in the solar system.
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  • How Many Satellites Does Mars Have?

    Q: How Many Satellites Does Mars Have?

    A: Mars has two very small satellites orbiting it, Phobos and Deimos. Scientists believe that both moons are actually asteroids captured via Mars's gravitational field. Made of dark rock that includes a great deal of carbon, both satellites have many craters due to collisions with debris.
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  • Why Is Pluto Not a Planet?

    Q: Why Is Pluto Not a Planet?

    A: In 2006, the International Astronomical Union changed Pluto's classification from a planet to a dwarf planet because the planet has not cleared its orbit of other objects. When a planet clears its orbit, all other objects on the orbital path are either drawn into the planet's gravitational pull or flung away from it and out of the orbit.
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