SP7 - Astronomy ✓

The model of our solar system in which everything orbits the earth.

The current model of our solar system where the sun is at the centre and other planes orbit it.

Elliptical

• Computers allow detailed analysis. • Photography allows accurate and permanent storage of events. • Telescopes can now be place outside of the earth’s atmosphere giving wider and more detailed detection. • Space probes allow better analysis of the solar system.

• The earth’s atmosphere absorbs many waves of the EM spectrum. • Outside the atmosphere, these could be detected. (such as infrared radiation)

Your weight is the force acting on you dependant on your mass and the gravitational field strength.

9.81 N/Kg (Can be rounded to 10N/Kg)

• Highly elliptical • Circular geostationary • Low earth orbits • Polar orbits

• Satellites that stay in the same place relative to the earth’s position. • They move at 3070 m/s and are used for broadcasting.

Polar orbits

Low earth orbits

Highly elliptical orbits

The gravitational force between the earth and the satellite causes it to continuously change direction and orbit the earth.

90°

• The gravitational force on an object in a lower orbit is a stronger than at a higher orbit so a satellite at a lower orbit would have to travel at a higher speed to stay in orbit. • Once it eventually slows down, it will drop towards earth. • However as it drops it gains speed and will eventually be able to be at a lower orbit at a faster speed. • Once it drops enough that it passes through the earth’s atmosphere, the air resistance will slow it down and it will eventually fall to earth.

Nuclear fusion (typically H + H = He)

• It starts with a Nebula (A cloud of gas). • The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar. • Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium • The energy released form the fusion reactions push the star outward causing it to expand. • Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium • Eventually, hydrogen runs out and heavier reactions take place. • This creates more energy which expands the star more • The outermost layers are no longer held in place by the force of gravity so they expand forming a red giant • Once all the fuel has run out, all the layers disband forming a shell of gas. • This leaves behind a highly dense white dwarf which doesn’t carry out any reactions.

• It starts with a Nebula (A cloud of gas). • The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar. • Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium • The energy released form the fusion reactions push the star outward causing it to expand. • Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium • Eventually, hydrogen runs out and heavier reactions take place. • This creates more energy which expands the star more forming a red supergiant. • These heavier fusions are carried out all the way to iron when it runs out of fuel. • The star rapidly collapses causing a supernova • This leaves behind a very dense neutron star • If the mass of the star is even larger, then a black hole is formed in place of the neutron star.

When the pitch of a noise get lower as it travels aways from you. (and higher when it travels towards you)

As a sound travels, the wavelengths are squashed or stretched meaning the sound’s pitch appears higher or lower.

When light form distant galaxies shift towards the red side of the spectrum due to wavelengths being stretched as the galaxy moves away from earth.

Absorption spectrums of the galaxy compared to the absorption spectrum of the sun.

• The big bang theory • Steady state theory

• The whole universe started out from one point of concentrated energy. • All matter started form this point and continued to expand outwards as the universe constantyl expands.