Astrophysics

Comparing Red-Shift with Elements (1)

Most galaxies are moving away from each other

Comparing Red-Shift with Elements (2)

Different elements absorb different frequencies of light

Comparing Red-Shift with Elements (3)

Light passes through forming dark lines at each frequency of visible light the element absorbs

Comparing Red-Shift with Elements (4)

More distant galaxies have the same patterns at a lower frequency

Comparing Red-Shift with Elements (5)

The patterns are shifted towards the red end of the spectrum

Big Bang

More distant galaxies = greater red shifts

More distant galaxies = moving away faster

Whole universe must be expanding

Microwave Radiation

Coming from all directions in all parts of the universe called CMBR. As the universe expands and cools, the radiation drops in frequency.

Star Colour

All stars emit visible light. Frequency and amount is dependent on surface temperature. The hotter the star, the bluer the light emitted.

White stars

All frequencies of visible light produced equally

Brightness of a star

Brightness depends on size and temperature.

Brightness in terms of distance from Earth

Closer stars appear brighter

Absolute Magnitude

How bright a star would appear to be if it was a fixed distance from Earth. The lower the absolute magnitude the brighter the star.

HR Diagrams

Absolute Magnitude vs Temperature

Where are the red giants and supergiants?

Top right

Where are the main sequence stars?

Middle of the HR diagram stretching from top left to bottom right

Where are the white dwarfs?

Bottom left of the HR diagram

Red-shift

A change in frequency that is shifted towards the red end of the spectrum showing that the source is moving away from the observer.

Planet Orbits

Around the Sun, almost circular.

Gravity in Orbits

Gravity is always acting on the object and pushing towards the centre of the orbit so the object constantly changes direction.

Orbital Radius

Faster objects will have smaller orbital radii than slower ones.

Comet vs Planet/Satellite

Very elliptical vs slightly elliptical

Longer orbital periods vs shorter orbital periods

Travels much faster when closer to the Sun vs Travels at an even speed throughout

Geostationary Satellites

They have the orbit of one day so they are always in the same place above the Earth