P16 - Space Flashcards
Which galaxy is our solar system part of?
The Milky Way galaxy.
How many planets make up our solar system?
Eight (plus the dwarf planets)
What do the planets in our solar system orbit around and what type of body is it?
● The planets orbit around the sun
● The sun is a star
What type of force pulled together the cloud of dust and gas to form the Sun?
Gravitational force of attraction.
What word is used to describe a cloud of dust and gas?
A nebula.
What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?
Fusion reactions
What factor determines the type of lifecycle a star undergoes?
The size of the star.
Which two phases do all stars of the same or greater size than the sun undergo?
- Protostar phase
- Main sequence phase
What do stars of a similar magnitude to the sun become at the end of their life-cycle?
A black dwarf.
What two things can stars much bigger than the sun become at the end of their lifecycle?
- Neutron star
- Black hole
What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?
- Red giant
- White dwarf
What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?
- Red super giant
- Supernova
What are produced during the fusion processes in a star?
All of the naturally occurring elements.
What condition is required for fusion reactions to occur in a star?
Very high temperatures.
How are elements heavier than iron produced?
In a supernova.
What type of nuclei fuse together to form heavier elements in a star?
Hydrogen nuclei fuse to form heavier elements.
How are elements distributed throughout the universe?
Through the explosion of a massive star (supernova).
What allows planets and satellites to maintain circular orbits?
● Gravity provides the gravitational force that acts as the object’s centripetal force
● The presence of a centripetal force allows for the object to maintain its
circular orbit
What type of satellite can a planet’s moon be described as?
A natural satellite.
Give two examples of artificial satellites.
- TV satellites
- Satellites used for satellite imaging
Explain why for a stable orbit, the radius of orbit must change if the speed changes.
● At higher speeds, the object requires a greater centripetal force
● For a greater centripetal force, the gravitational force must increase
● This is achieved by the radius of the orbit being reduced
Explain how the force of gravity acting on a satellite affects its speed and velocity.
● The force can alter its velocity since the direction is continually changing
● It can’t cause a change of speed since there is no force component in the direction of motion
What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
● The further away a galaxy is, the faster it is moving
● The further away a galaxy is, the greater the observed increase in wavelength
What does red-shift provide evidence for?
● Provides evidence that the universe is expanding
● Supports the Big Bang theory
What does the Big Bang theory suggest?
The entire universe started from a very small, hot and dense region in space.
Compare the observed red-shift of two galaxies, one further away than the other.
● The galaxy that is further away is travelling faster
● The observed red-shift is greater the further away it is
What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?
They observed supernovae, which suggested that galaxies are moving away at an ever faster rate.
Prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?
● The rate of expansion was expected to occur at an ever slower rate
● It was thought that gravitational forces would cause this slowing down
What two ideas could explain the universe’s ever increasing rate of expansion?
● The existence of energy and mass that we can’t detect, known as dark matter and dark energy
● These ideas are still being developed by scientists and are not yet fully understood
What is the Big Bang Theory?
- Big Bang theory: Universe began as a single dense point.
- Rapid expansion: Initiated a hot explosion.
- Continuous expansion: Universe still getting larger.
- Creation event: Space, time, matter formed in Big Bang.
What is a black dwarf?
A star that has faded out and gone cold
What is a black hole?
An object in space that has so much mass that nothing, not even light, can escape from its gravitational field
what is centripetal force?
The resultant force towards the centre of a circle acting on an object moving in a circular path
What is cosmic microwave background radiation (CMBR)?
- Electromagnetic radiation from Big Bang
- Originally gamma radiation
- Now seen as microwave due to Doppler effect
What is dark matter?
Matter in a galaxy that cannot be seen. Its presence is deduced because galaxies would spin much faster if their stars were their only matter
What is main sequence?
The main sequence is the life stage of a star during which it radiates energy due to fusion of hydrogen nuclei in its core
What is a neutron star?
The highly compressed core of a massive star that remains after a supernova explosion
What is a protostar?
The concentration of dust clouds and gas in space that forms a star
What is a red giant?
A star that has expanded and cooled, resulting in it becoming red and much larger and cooler than it was before
What is a red supergiant?
A star much more massive than the sun will swell out after the main sequence stage to become a red supergiant before it collapses
What is red-shift?
- Redshift: Increase in wavelength of star/galaxy waves due to motion away.
- Speed correlates: Faster motion = greater redshift.
- Effect: Wavelength shift towards longer (redder) wavelengths.
What is a supernova?
The explosion of a massive star after fusion in its core ceases and the matter surrounding its core collapses onto the core and rebounds in an explosion
What is a white dwarf?
A star that has collapsed from the red giant stage to become much hotter and denser
What is a planet?
A planet is an object in orbit around a star that has cleared their orbit of other objects
What are moons?
A body in orbit around a planet
What is a comet?
- Frozen rocks
- Move around the sun
- Elliptical orbits
- Far from the sun at times
- Visible when near the sun
- Heat up and emit light
Why can you only see a comet when it is near the sun?
You can only see them when they return near the Sun because then they heat up so much that they emit light.
What are meteors?
Small bits of rock that burn up when they enter the earths atmosphere
What are minor (dwarf) planets?
Dwarf planets have not cleared their orbit of other objects.
What are asteroids?
Asteroids are objects too small and uneven to be planets, usually in near-circular orbits around the Sun and without the ice present in comets.
Describe the birth of a star? 6 marks
- Stellar nebula: Large cloud of dust and gas in space.
- Gravitational attraction pulls nebula together.
- Dense regions form protostar as clouds merge.
- Protostar heats up as it becomes denser.
- Fusion of lighter nuclei releases energy.
- Energy release makes protostar hotter.
- Protostar shines brighter, becoming a main sequence star.
- Nuclear fusion balances gravity’s inward pull.
How does a planet form?
The star’s gravity pulls smaller amounts of dust and gas together, forming planets in orbit of the star
Explain how main sequence stars are stable, and how the star becomes unstable. 6 marks
- Main sequence star: Stable due to balanced forces inside.
- Gravity pulls inward, radiation from fusion pushes outward.
- Fusion in core keeps star hot and stable.
- Gamma radiation emitted steadily from core.
- Balance maintained until hydrogen fusion depletes.
- Depletion leads to star instability.
What force pulls the dust and gas together to form a protostar?
Gravitational attraction
State the 5 stages of the life cycle of a star the same size as our sun:
• Protostar
• Main Sequence Star
• Red Giant
• White Dwarf
• Black Dwarf
State the 5 stages of the life cycle of a star the much bigger than our sun?
• Protostar
• Main sequence star
• Red Super Giant
• Supernova
• Neutron star / Black hole
Explain why low mass stars remain in the main sequence for much longer than large mass stars
Stars with low masses remain in their main sequence stage for much longer, as their core is cooler than that of more massive stars, therefore fusion takes place at a slower rate
Explain the life cycle of a low-mass star? 6 marks
- Star forms from nebula of dust and gas.
- Gravity pulls matter into protostar.
- Fusion starts in protostar, releases energy.
- Main sequence: fusion balances gravity.
- Hydrogen runs out, star swells into red giant.
- Core contracts, fusion of helium and heavier elements.
- Fusion stops, star ejects outer layers.
- White dwarf forms, cools over time.
- Cooling continues to black dwarf stage.
Explain the life cycle of a high-mass star? 6 marks
- Star formation starts in a nebula of dust and gas.
- Gravity causes the nebula to collapse, forming a protostar.
- Hydrogen fusion begins in the dense protostar, releasing energy.
- Balanced by fusion pressure, the star enters the main sequence phase.
- Hydrogen depletion leads to expansion into a red supergiant.
- Core contraction initiates fusion of heavier elements like helium.
- Multiple contractions and expansions precede a supernova explosion.
- Supernova ejects heavy elements and forms either a neutron star or black hole.
- Neutron stars are dense neutron objects; black holes have extreme gravity.
How are elements up to Iron formed?
Nuclear fusion in the core of a red giant / red supergiant
How are elements larger than iron formed?
- Supernova explosion forms heavy elements larger than iron.
- Collapse during supernova fuses small nuclei into larger ones.
- Explosion scatters these elements across the universe.
What are the 2 types of satellites?
• Natural Satellite (e.g. the moon)
• Artificial Satellite (e.g. a space telescope)
What is a satellite?
Anything that orbits a celestial body
What are the uses of artificial satellites?
• Communication
• Photography
• Navigation
• Experimentation
• Weather Predictions
What are the 2 types of orbits?
• Circular Orbit
• Elliptical Orbit
What orbit does the moon take around the earth?
Circular
What keeps objects in orbit around other bodies?
Objects orbit much larger bodies due to the force of gravity. The gravitational pull of the large body on the smaller object keeps it in orbit
What are geostationary satellites?
Geostationary satellites are satellites which orbit the earth once every 24 hours, this means they always face the same part of the earth, they are further away than other artificial satellites
What are polar orbits?
Polar orbits take the satellites over the Earth’s poles. The satellites travel very close to the Earth, so they must travel at very high speeds
Explain why objects orbiting another body have a constant speed but their velocity is constantly changing:
- Objects in circular orbit have constant speed.
- Direction changes constantly.
- Velocity changes due to direction change.
- Constant velocity change means constant acceleration.
Explain why an object in orbit does not fall into the larger body?
- Centripetal force of gravity accelerates object towards the center.
- Object’s velocity is at a right angle to the centripetal force.
- Gravity changes the object’s direction, not speed.
- Result: object orbits the larger body.
In which direction does centripetal force act?
Towards the centre of the circle
At what angle is the direction of the planets motion to the force of gravity exerted by the sun?
90°
What happens if a satellites is travelling too slowly for the radius of its orbit?
If the satellite travels too slow, then the gravitational attraction will be too strong, and the satellite will fall towards the Earth.
Why can an object not orbit too close to a planet with an atmosphere?
atmospheric drag would slow the object, causing it to fall into the planet’s surface
What happens if a satellites is travelling too fast for the radius of its orbit?
If the satellite travels too fast, then the gravitational attraction between the Earth and the satellite is too weak to keep it in orbit. If this is the case, the satellite will move off into space.
Explain how the speed of a satellite must change for the satellite to continue orbiting if the orbit radius is decreased?
The speed of the satellite must increase as the force of gravity on the object is greater, therefore it must travel faster to prevent crashing into the surface of the body
Explain how the speed of a satellite must change for the satellite to continue orbiting if the orbit radius is increased:
The speed of the satellite must decrease as the force of gravity on the object is lower, therefore it must travel slower to prevent flying off into space
Explain how the orbit radius must change for the satellite to continue orbiting if a satellite orbits faster?
The orbit radius must decrease, this is because it requires a stronger gravitational pull to prevent flying off into space
Explain how the orbit radius must change for the satellite to continue orbiting if a satellite orbits slower?
The orbit radius must increase, this is because it requires a weaker gravitational pull to prevent crashing into the planet
What is a theory?
- Theories explain phenomena in our universe.
- Theories cannot be proven, only disproven.
- Disproven theories lead to new explanations.
- Strongly supported theories become dominant.
What time period does the Big Bang Theory explain?
the origin of the universe and the evolution of the universe from that point, it does not explain anything before the big bang
What causes scientists to discredit one theory in favour of another?
If new evidence / observation cannot be explained by one theory but can be explained by another
What are the advantages and disadvantages of using a balloon with dots on the outside to model the expanding universe?
- Advantages:
• It shows the expansion of space and shows how galaxies are moving apart - Disadvantages:
• Balloons can only stretch so far
• There would be galaxies inside the balloon as well
Describe how the relative speed of a star or galaxy effects the shift (red shift / blue shift)
If the relative speed is greater, the shift is greater
Explain what a galaxy showing blue shift can tell us about the galaxy:
The galaxy that is showing a blue shift is approaching the earth, this is because when a source moves towards an observer, the observed wavelength decreases and the frequency increases, causing the light to shift towards the blue end of the spectrum.
Explain what a galaxy showing red shift can tell us about the galaxy:
The galaxy that is showing a red shift is moving away from the earth, this is because when a source moves away from an observer, the observed wavelength increases and the frequency decreases, causing the light to shift towards the red end of the spectrum.
Explain how red shift and blue shift can be identified:
- Passing light through gas absorbs certain wavelengths.
- This forms an “absorption spectrum.”
- Compare distant stars’ absorption spectrum to the sun’s.
- Observe shifts in absorption lines.
- Determine red shift (moving away) or blue shift (moving closer).
Explain how red shift supports the Big Bang theory
- Light spectra from stars and the edge of the universe show a red shift.
- Red shift indicates the universe is expanding.
- As a source moves away, observed wavelength increases and frequency decreases, causing red shift.
- This supports the Big Bang Theory.
- Suggests the universe began from a small initial point and has been expanding since.
What is the doppler effect?
- Doppler Effect:
- Source still: Wavelength and frequency constant
- Source moves toward observer: Wavelength decreases, frequency increases
- Source moves away from observer: Wavelength increases, frequency decreases
What was created in the Big Bang?
Space, time, and matter
What is the steady state theory?
The steady state theory says that the Universe has always existed, and that the Universe is expanding and constantly creating matter as the Universe expands.
Explain the differences between the Big Bang theory and steady state theory
-
Big Bang Theory:
- Universe began at a single point
- Sudden explosion led to expansion
- All matter and energy originated at that point
-
Steady State Theory:
- Universe has no origin; always existed
- Matter is continuously created as the universe expands
What is the origins of CMBR?
Radiation produced during the Big Bang
How is the wavelength of CMBR likely to change over the next billion years?
It is likely to increase as the universe is constantly expanding, this means that red shift will occur causing the CMBR to have a longer wavelength
What does the future of the universe depend on?
The Density of galaxies
What are the 2 possible futures of the universe?
• The Big Yawn
• The Big Crunch
What is the Big Yawn?
If the density of the universe is less than a particular amount, then the universe will continue to expand at an ever increasing rate until the stars will die out and everything else with them
What is the Big Crunch?
If the density of the universe if more than a particular amount then it will stop expanding and start contracting
How is dark matter known to exist and what does the existence of dark matter mean?
- Stars make up a small part of a galaxy’s mass.
- Galaxies would spin faster if only stars contributed to their mass.
- Missing mass is attributed to dark matter.
- Dark matter increases the average density of the universe.
What theory does red-shift support?
Both the big bang theory and steady state theory
What theory does CMBR support?
The Big Bang theory
What is causing galaxies to accelerate away from each other?
Dark energy
Why is an orbiting object constantly accelerating?
It is experiencing a constant change in velocity.
Explain how a galaxies speed changes with distance and how this can be detected and what is suggests?
- Distant galaxies move away faster.
- Detected by greater red shifts in absorption lines.
- True in all directions in space.
- Indicates galaxies are moving apart; universe is expanding.
- Red shift: wavelength increases, frequency decreases when a source moves away.
What is hubbles law?
A law stating that the red shifts in the spectra of distant galaxies are proportional to their distance.
describe the universe when it first began
The universe was extremely hot and dense
Why is peer review important?
Helps detect bias or inaccurate data
