8 Astrophysics Flashcards
Universe
A large collection of billions of galaxies
Galaxies
A large collection of billions of stars
What is our galaxy called?
The milky way
Weight
The force due to gravity
Caused by the gravitational force of attraction of a planet on an object
Gravitational Field Strength (g)
The force per unit mass on an object in a gravitational field
Where does Gravitational Field Strength vary?
On different planets, due to size and mass
As size and mass increases, gravitational field strength increases
What does gravitational force of attraction cause?
Moons to orbit planets
Planets to orbit the Sun
Comets to orbit the Sun
Artificial satellites to orbit the Earth
Gravitational force of attraction
For an object to go round in a circle, a force towards the centre of the circle is needed
Example of gravitational force of attraction
The sun puts a gravitational force of attraction on Earth
Types of orbit
Elliptical
Circular
Stellar Evolution
When stars change over time
How can stars be classified?
By their colour -> relates to their surface temperature
ROYGBIV
R = cool
V = hot
Absolute Magnitude
Measure of the brightness of a star from a fixed distance on earth
How does absolute magnitude change with brightness?
The higher the absolute magnitude, the lower the brightness of the star
Big Bang
- All the matter in the universe came from a single point
- This point was very dense + hot
- This point exploded
- The universe is expanding outwards from a single point
What is the big bang proved by?
Red-Shift
Cosmic Microwave Background Radiation (CMBR)
Doppler Effect
When a source is moving relative to an observer, the waves change in frequency and wavelength
Light emitted by stars will be a certain wavelength on the visible spectrum
What happens in the Doppler Effect?
When the object is moving away from the observer, the wavelength of light increases/frequency decreases
Red Shift
The light waves shift towards the red end of the visible spectrum
Shows that the star is moving away (longer wavelength is observed than expected)
Blue Shift
The light waves shift towards the blue end of the visible spectrum
Cosmic Microwave Background Raditation (CMBR)
- When the big bang occurred, many gamma rays were released
- As the universe expands, these gamma rays have stretched out into mcrowaves
- Its the same in all direction, showing the universe started at a single point
