Biology 🧬🦠🌱🌿

• Celestial bodies


  Many bodies found in the universe such as stars, planets, moons, etc.
• All celestial bodies are in permanent motion according to the will of Allah
• Celestial bodies


  Bodies that swim in space such as stars, planets, moons and rocky or gaseous bodies
• Stars


  Big-sized bodies that emit enormous amounts of heat and light
• Stars appear small although they are big-sized because they are millions of kilometres away from us
• Light year


  The distance covered by light in one year, equals 9.467 x 10^12 km
• The distance between the Sun and a star is three light years, which means 28.401 x 10^12 km
• Calculating distance in light year

  Distance in km / 9.467 x 10^12
• Calculating distance in km


  Distance in light year x 9.467 x 10^12
• The stars seem as light points although they are huge because they are far from us
• Astronomers do not measure the distances between stars in kilometres because these distances are too huge
• Galaxies


  The greatest units that form the universe, a tremendous collection of stars
• Milky Way galaxy


  The galaxy that our solar system belongs to, takes an oval shape with coiled spiral arms
• The Milky Way galaxy appears in the sky at night as a splashing milk or spreading straw
• Telescopes


  Instruments used by astronomers to identify celestial bodies
• The first scientist who invented a telescope to monitor space was Galileo
• Components of the solar system

  • The Sun
  • Planets
  • Moons
  • Asteroids
  • Meteors
  • Meteorites
  • Comets
• The Sun


  The star of our solar system, the biggest body in the solar system, lies at the centre and other bodies revolve around it
• Planets


  • Eight spherical opaque bodies that revolve around the Sun in one direction (anti-clockwise) in semi-circular or elliptical paths
  • Their paths lie in one plane perpendicular to the Sun's axis of rotation
• Planets ordered by distance from the Sun

  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
• Planets ordered by size


  • Jupiter
  • Saturn
  • Uranus
  • Neptune
  • Earth
  • Venus
  • Mars
  • Mercury
• Inner (small) planets


  • The nearest four planets to the Sun, small and rocky with solid surfaces
• Outer (big) planets


  • The farthest four planets from the Sun, big and gaseous with low densities
• Mercury and Venus have no moons, Earth has one moon, Mars has two moons, and the outer planets have large numbers of moons
• The presence of hydrogen gas in a solidified state on the surface of outer planets is due to the high pressure and extreme coldness
• Gravity


  The force of gravity between objects in space depends directly on their masses and inversely on the distance between them
• Planets ordered by gravity on their surface

  • Mars
  • Mercury
  • Uranus
  • Venus
  • Saturn
  • Earth
  • Neptune
  • Jupiter
• The Earth has larger gravity on its surface than Mars because the Earth's mass is larger
• Asteroids


  Thousands of different sized rocky masses that rotate around the Sun in the "belt of the wanderer asteroids" between Mars and Jupiter
• Meteors


  Small rocky masses that burn up completely when falling through the Earth's atmosphere due to friction heat
• Meteorites


  Large rocky masses that do not burn up completely when penetrating the Earth's atmosphere, with the remaining part falling on the Earth's surface
• Meteorite


  A large asteroid that penetrates the Earth's atmosphere, with its outer surface burning and the remaining part falling on the Earth's surface without burning
• The biggest meteorite till now has a mass of 80 tons and exists at the southern west of Africa
• Comet


  • Masses of rocks, ice and solidified gases that revolve around the Sun in more elongated elliptical orbits intersecting with the orbits of the planets
• Structure of comet


  1. Head

  2. Tail
• Comet's head


  The first part of the comet, containing icy spheres which are a mixture of solidified gases, rocky parts, dust and water molecules
• Comet's tail


  The second part of the comet, considered a gaseous cloud
• The most famous comet is Halley, which completes its revolution around the Sun every 76 years
• Celestial bodies


  • They are bodies swia
• Light year


  It is the distance co