General Knowledge - Solar System


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  • There are eight planets namely (arranged in the order of increasing distance from the Sun) −

    • Mercury

    • Venus

    • Earth

    • Mars

    • Jupiter

    • Saturn

    • Uranus

    • Neptune

  • The largest planet is Jupiter and Mercury is the smallest planet of the system.

Sun

Mercury

  • Mercury is the nearest to the Sun.

  • Mercury takes 58.65 Earth days to complete its rotation (on its axis) and takes 88 days to complete its one revolution (i.e. in its orbit around the Sun).

  • Mercury is the fastest planet and it has no moon (satellite).

Venus

  • Venus, which is also popular as an evening star and morning star, is the brightest celestial body in the universe after Sun and Moon.

  • Venus is the Hottest Planet of the solar system. It is closest to the Earth.

  • Venus takes 243 Earth days to complete its rotation (on its axis) and takes 224.7 days to complete its one revolution (i.e. in its orbit around the Sun).

  • Venus has no satellite and it spins in the opposite direction of the Earth’s spin.

  • Venus is named after the Roman goddess of Beauty.

Earth

  • Earth is the third planet from the Sun.

  • By the time, Earth is the only planet where life exists.

  • Earth takes 23 hours, 56 minutes, and 40 seconds to complete its rotation (on its axis) and takes 365.26 days to complete its one revolution (i.e. in its orbit around the Sun).

  • Mass of the Earth is 5.98 x 1024 kg and its diameter is 12,756 km.

  • Escape Velocity of the Earth is 11,200 m/s.

  • Obliquity (i.e. tilt of axis degrees) of the Earth is 23.40.

  • Mean density of the Earth is 5.514 g/cm3 and the surface is 510,072,000 km2.

  • Mean surface temperature of the Earth is 281 K; the mean maximum surface temperature is 310 K and the mean minimum surface temperature is 260 K.

  • The major atmospheric components of the Earth are Nitrogen (78%), Oxygen (20.95%), Argon (0.930%), and Carbon Dioxide (0.039%).

Moon

  • Moon is the only known satellite of the Earth.

  • Moons rotation time (on its axis) and revolution time (around the Earth) is same (i.e. 27 days, 7 hours, 43 minutes, and 11.47 seconds. This is the reason that we always see only one side of the Moon.

  • Moon revolves around the Earth once in every 27.3 days, which is known as ‘Sidereal Month;’ however, it takes 29.5 days to return to the same point on the celestial sphere in reference to the Sun (due to revolution motion of the Earth around the Sun) and it is known as ‘Synodic Month.’

  • When two full Moons occur in the same month, it is known as ‘Blue Moon.’

  • A Full Moon is basically the lunar phase that occurs when the Moon is completely illuminated as seen from the Earth.

  • As shown in the following image, the Lunar Phase or phase of the moon, is the shape of the illuminated portion of the Moon that is visible from the Earth. As Moon revolves, the lunar phases change cyclically and we can see from the full moon (full visible) to the new moon (not at all visible).

Moon

Mars

  • Mars is known as the ‘Red Planet’ of the solar system.

  • Mars takes 24 hours, 37 minutes, and 30 seconds to complete its rotation (on its axis) and takes 687 days to complete its one revolution (i.e. in its orbit around the Sun).

  • Mars has two satellites namely Phobos (means fear) and Deimos (means terror).

Jupiter

  • Jupiter takes 9 hours, 50 minutes, and 30 seconds to complete its rotation (on its axis) and takes 12 earth years to complete its one revolution (i.e. in its orbit around the Sun).

  • Jupiter has 63 natural satellites/moon, significant of them are Europa, Ganymede, Callisto, etc. Among all, Ganymede is the largest satellite in the whole solar system.

Saturn

  • Saturn is the largest planet after Jupiter in the solar system.

  • Saturn is popular for its spectacular rings system.

  • The rings system of Saturn is made up of a variety of separate particles that rotate in circular orbits independently.

  • Saturn takes 10 hours and 14 minutes to complete its rotation (on its axis) and takes 30 years to complete its one revolution (i.e. in its orbit around the Sun).

  • Saturn has total 47 satellites/moons; among them, Titan is the biggest satellite.

Uranus

  • Uranus is first identified as planet by William Herschel in 1781.

  • Like Saturn, Uranus also has a system of five faint rings.

  • Uranus takes 16 hours to complete its rotation (on its axis) and takes 84 years to complete its one revolution (i.e. in its orbit around the Sun).

  • Uranus has 27 satellites; significant of them are Miranda, Ariel, Umbriel, Titania, etc.

Neptune

  • Neptune is the farthest planet which appears greenish through a telescope.

  • Neptune is discovered by Berlin scientist J. G. Galle in 1846.

  • Neptune takes 18 hours to complete its rotation (on its axis) and takes 165 years to complete its one revolution (i.e. in its orbit around the Sun).

  • Neptune has 13 satellites/moons; significant of them are ‘Triton’ and ‘Nereid.’

  • Until 2006, there were nine planets (including Pluto), but in 2006, the ninth planet Pluto is categorized as the dwarf planet by International Astronomical Union (IAU).

Asteroids

  • Asteroids, also known as small planets or planetoids, are the rocky debris largely found between the planets Mars and Jupiter. These are too small to have their own atmosphere (as shown in the following image).

Asteroids
  • The Asteroids revolve around the Sun, which varies from 3 to 10 years.

  • By the time, more than 450,000 Asteroids are discovered; the largest Asteroid is Ceres, which diameter is about 1,025 km.

Meteors

  • Meteors, also popular as ‘Shooting Star’ or ‘Falling Star,’ is the passage of a comet, asteroid, or meteoroid into the Earth's atmosphere. It is heated (because of the collisions with air particles) and normally seen in the upper atmosphere (as shown in the following image).

Meteors
  • Meteoroids are the small rocky or metallic bodies that normally travel through outer space. Meteoroids are expressively smaller than asteroids, and its size ranges from small grains to 1-meter-wide objects.

Comets

  • Comets are the icy small Solar System body; normally while passing close to the Sun, heats up and starts to outgas, displaying a visible atmosphere (i.e. basically coma) along with a tail (as shown in the following image – in the insat view).

Comets

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