Space

• Within our solar system there is one star (the Sun) plus the eight planets and the dwarf planets that orbit around the Sun
• Natural satellites (the moons that orbit planets) are also part of the solar system.
• Our solar system is a small part of the Milky Way galaxy.
• The Sun was formed froma cloud of dust and gas (nebula) pulled together by gravitational attraction.
• The start of a stars lifecycle:

  • Stars initially form a cloud of dust and gas called a nebula
  • The force of gravity pulls the dust and gas together to form a protostar
  • The temp rises as the star gets denser nd more particles collide
  • when the temp gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei
  • This gives out huge amounts of energy which keeps the core of the star hot
  • A star is born
• A star goes through a life cycle. The life cycle is determined by the size of the star
• Fusion processes in stars produce all of the naturally occurring elements. Elements heavier than iron are produced in a supernova.

  The explosion of a massive star (supernova) distributes the elements throughout the universe.
• Gravity provides the force that allows planets and satellites (both natural and artificial) to maintain their circular orbits.
• planets- large objects that orbit a star, there are 8 in our solar system

  they have tobe large enough to have ‘cleared their neighbourhoods’, this means that their natural gravity is strong enough to have pulled in any nearby objects apart from their natural sattelites
• moons- orbit planets

  they’re a type of natural satellite
• artificial satellites- are satellites that humans have built, they generally orbit the earth
• There is an observed increase in the wavelength of light from most distant galaxies. The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength. This effect is called red-shift.
• The observed red-shift provides evidence that space itself (the universe) is expanding and supports the Big Bang theory.
• The Big Bang theory suggests that the universe began from a very small region that was extremely hot and dense.

  Since 1998 onwards, observations of supernovae suggest that distant galaxies are receding ever faster.
• Life cycle of stars :

  A) main sequence star

  B) red giant

  C) white dwarf

  D) black dwarf

  E) neutron star

  F) black hole

  G) super nova

  H) red super giant

  I) protostar

  J) (nebula)