P16 Flashcards
Space
What are comets ?
frozen eliptical rock bodies that emit light due to heating when near the sun
What are meteors ?
small rocks that heat so much due to friction that they vaporise in Earth’s atmosphere
What are meteorites ?
meteoroids that survive the fall to Earth (usually larger too)
Describe the life cycle of a star like our sun, including the elements formed at each stage
- nebula drawn closer together by its own gravitational force, generating heat and forming a protostar
- protostar continues drawing closer together and generating heat until it is hot enough to begin nuclear fusion
- star is now in its MSS (main sequence stage)
[] hydrogen atoms are fused together to make helium - when star runs out of hydrogen to fuse together, it becomes a red giant
[] grows massively in size due to sudden imbalance of outward force of fusion and inwards force of gravity
[] cools
[] fuses helium and other light elements to form elements up to carbon on the periodic table - once runs out of light elements to fuse, fusion stops
[] gravity becomes stronger than fusion force and so star implodes becoming much smaller - becomes a small, dense, hot white dwarf
- eventually dies as a black dwarf
Describe the life cycle of a star bigger than our sun (but not the biggest)
- nebula drawn closer together by its own gravitational force, generating heat and forming a protostar
- protostar continues drawing closer together and generating heat until it is hot enough to begin nuclear fusion
- star is now in its MSS (main sequence stage)
[] hydrogen atoms are fused together to make helium - when star runs out of hydrogen to fuse together, it becomes a SUPER red giant
[] star grows MASSIVELY due to sudden imbalance of forces (making heavier elements means more energy released so outwards force of fusion outweighs gravity)
[] star cools
[] helium and other light elements are fused to make elements up to iron on the periodic table - once star runs out of elements to fuse again, supernova (huge explosion)
[] all other natural elements after iron on the periodic table formed in the explosion and scattered across the universe to embed in the crusts of planets and to act as particles of protostars/nebulas - star becomes a neutron star
[] 12-18km across
[] INCREDIBLY DENSE
[] made only of neutrons
Describe the life cycle of the very biggest star
- nebula drawn closer together by its own gravitational force, generating heat and forming a protostar
- protostar continues drawing closer together and generating heat until it is hot enough to begin nuclear fusion
- star is now in its MSS (main sequence stage)
[] hydrogen atoms are fused together to make helium - when star runs out of hydrogen to fuse together, it becomes a SUPER red giant
[] star grows MASSIVELY due to sudden imbalance of forces (making heavier elements means more energy released so outwards force of fusion outweighs gravity)
[] star cools
[] helium and other light elements are fused to make elements up to iron on the periodic table - once star runs out of elements to fuse again, supernova (huge explosion)
[] all other natural elements after iron on the periodic table formed in the explosion and scattered across the universe to embed in the crusts of planets and to act as particles of protostars/nebulas - star becomes a black hole
[] gravitational field so strong that not even light can escape
What is a satellite ?
A body continually falling in a larger body’s orbit
What is centripetal force ?
the gravitational force acting towards the centre of an orbit
- this is what keeps satellites in orbit
How do you get objects into orbit ?
Launch them at the correct angle and velocity
[] too slow/close to Earth, satellite experiences too much drag/air resistance from atmosphere and so simply falls
[] too quick/far from Earth, satellite launches into space
Describe how a satellite is kept in orbit
- constantly falls at the correct angle so that the larger body’s surface curves away underneath constantly
- centripetal force experienced is always at right angles to larger body so experiences acceleration towards the centre of the larger body
[] magnitude of velocity DOESNT change but direction of velocity DOES
Give the formula for a complete orbit
orbit = circumference of larger body/orbital body’s speed
How does the speed of an orbital body depend on its distance from the larger body ?
- further = gravitational force weaker
- needs less speed to stay in orbit thus falls slower
- closer = gravitational force stronger
- needs more speed to stay in orbit thus falls more quickly
How does the radius of an orbit change ?
When the speed of a satellite in stable orbit changes
- closer to larger body = faster speed and smaller radius
- further from larger body = slower speed and larger orbital radius
Describe the properties of the orbit of a geostationary satellite
- orbit 36 000 km above equator
- orbit time = 24h (same as one turn of the Earth)
- orbit the Earth at the same speed as it
- orbit in the same direction of the Earth’s spin
- ALWAYS REMAINS ABOVE THE SAME PLACE ON THE EARTH
Describe the properties of the orbit of a monitoring satellite
- much lower orbits than geostationary satellites
- orbit faster and have an orbital length of 2-3h
Give some uses of both geostationary and monitoring satellites
- geostationary
[] communications - monitoring
[] weather forecasts
[] monitoring environmental conditions
What is red shift ?
When a planet moves away from you, the light emitted gets stretched so appears more towards the red side of the visible light spectrum
What is blue shift ?
When a planet moves towards you, the light emitted gets compressed so appears more towards the blue side of the visible light spectrum
What do the black spectral lines on a graph representing blue/red shift mean ?
light absorption of source
- the shift of these black/dark lines shows red/blue shift
What is the relationship between greatness of red/blue shift and speed that the other planet is moving towards/away ?
greater shift = greater speed
How does red shift prove that the universe is expanding ?
- Earth has no special place in the universe
[] so planets are not ONLY moving away from Earth - all planets are moving away from each other
- the universe overall is expanding
What is Steady State Theory ?
- that the universe is expanding as a result of matter leaking into the universe via “white holes” (the opposite of black holes)
- this matter pushes everything else apart
What is the Big Bang Theory ?
- space, time and matter created in a huge explosion from a concentrated hot point
- this explosion created the universe
Describe the evidence for the Big Bang Theory
- due to huge explosion, high-energy electromagnetic radiation produced
- over time would have spread out to become lower energy radiation
- scientists detected this using microwave detectors on Earth and on satellites as cosmic microwave background radiation (CMBR)
[] existence can only be explained by the Big Bang Theory
What is dark matter and why do we know it’s there ?
- “invisible” matter that we can’t see
- means that the universe’s mass is probably much larger than appears
- if it wasn’t present, stars would spin much faster as there would be no other gravitational forces
Give two possible futures of the universe
- big yawn
[] if total density of universe is less than certain amount, universe will expand forever and everything will eventually die out - big crunch
[] if total density of universe is more than a certain amount, will stop expanding and collapse in on itself
What is dark energy ?
- attractive force possibly causing the acceleration apart of distant galaxies
- cannot be explained by gravity due to being an attractive force and thus acting against the outwards motion of galaxies moving apart
