Astronomy Flashcards
What is the order of the planets from the sun?
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
What is a moon?
A natural satellite that orbits a planet
What is a protostar?
Where nuclear fusion begins to form a star, hydrogen atoms fuse to form helium
Describe the life cycle of a star like our sun
- Cloud of dust forms called a nebula
- Then it becomes a protostar, and nuclear fusion begins
- Nuclear fusion leads to it being a main sequence star
- Nuclear fusion goes on until it becomes a red giant
- When fusion stops, the star will become a white dwarf
Describe the life cycle of a massive star
- Cloud of dust forms called a nebula
- Then it becomes a protostar, and nuclear fusion begins
- Nuclear fusion leads to it being a main sequence star
- Nuclear fusion goes on until it expands to become a red super giant
- When nuclear fusion stops a supernova will happen
- It will then become a neutron star or a black hole
What is an asteroid?
A small object composed of metal and rock that follows an elliptical orbit around its sun
What is a comet?
A small object composed of rock, dust and ice that follows an elliptical orbit around its sun
Other than what it’s made up of, what is different between a comet and an asteroid?
Comets begin to vaporise as they approach a star, turning it into gas which forms a distinctive tail
Describe the relationship between the weight of an object and the gravitational field strength
They are directly proportional
Describe the speed and velocity for things that follow circular orbits
The speed stays the same but the velocity changes due to gravity
How does the balance of thermal expansion and gravity affect the lifecycle of stars?
- Smaller stars have longer lives due to smaller forces of gravity, that are easier to balance
- Larger stars have shorter lives due to larger forces of gravity, that are more difficult to balance
Why is the gravitational field strength different for other bodies in space?
They have different masses
Why is a person’s weight different on a different planet?
Because the gravitational field strength is different
W = mg
What is a dwarf planet?
A body is space unable to clear its neighbourhood (meaning other things could be in the same orbit)
How have ideas about the structure of the solar system changed over time?
For a long time people believed in the geocentric model, with Earth in the centre and The Sun and planets orbiting around it
Do satellites in a circular orbit maintain a constant speed?
Yes
Do satellites in a circular orbit maintain a constant velocity?
No, due to changing direction
What do planets orbit?
A barycentre, the common centre of mass of itself and the star
What type of orbit does a planet follow?
Circular
What type of orbit does a moon follow?
Circular
What type of orbit does a comet follow?
Elliptical
What type of orbit do artificial satellites follow?
Circular
What happens if the speed of a satellite increases in a stable orbit?
The radius of the orbit will increase
What is redshift?
The increase in wavelength of light from objects moving away from Earth
What causes redshift?
The Doppler Effect
What does CMBR stand for?
Cosmic Microwave Background Radiation
How does CMBR prove the Big Bang theory?
- In 1948 microwave radiation was discovered across the sky (CMBR)
- According to the Big Bang theory, huge amounts of radiation was released during the Big Bang
- CMBR is the radiation left over from the explosion
What is the Big Bang theory?
The idea that the universe is constantly expanding and all matter was created in the Big Bang
What is the Steady State theory?
The idea that the universe has always existed and is constantly expanding and matter is also constantly being created
Which model for the origin of the universe is currently accepted and why?
The Big Bang theory because there is more evidence to support it
What evidence is there to support the Big Bang theory?
- Redshift
- CMBR
What evidence is there to support the Steady State theory?
Redshift
What does redshift prove about the universe?
It is constantly expanding
How does redshift prove that the universe is expanding?
Light from most stars has a higher wavelength (shifted to red), which means the universe is expanding, proven by the doppler effect.
What happens if a wave source is moving relative to an observer?
There will be a change in the observed frequency and wavelength
The further light is redshifted…
…the faster the object is moving away from us
Why doesn’t CMBR support the steady state theory?
According to the Steady State theory, the universe has always existed, therefore there can be no radiation emitted from an explosion that created the universe
Why are some telescopes are located outside the Earth’s atmosphere?
Because the atmosphere distorts the vision
How have methods of observing the Universe have changed over time?
- Originally people could only observe with the naked eye
- Telescopes were then invented allowing people see clearly into space
- Over time telescopes have become more powerful and some are positioned in space
