P1- The Earth In The Universe Flashcards
What is a planet?
Much smaller, reflect light and much closer
What is the formation of the universe?
- one cloud get squeezed slightly, particles love closer together. Gravity took over causing whole cloud to collapse in on itself.
- centre of collapse, particles come together to form a PROTOSTAR. Temperatures got hot enough for fusion to start.
- hydrogen nuclei joined together to make Helium
- fusion gives out a massive amount of heat and light, the sun was born
- all the chemical elements in the cloud with heavier atoms than hydrogen and helium were also formed in re star by fusion of different nuclei
- around the sun, material from the cloud containing hydrogen and helium and heavier elements started to clump together forming planets.
What’s an asteroid?
Smallish lumps of rubble and rock
What is a comet?
Balls of rock, dust and ice which orbit the sun in very elongated ellipses.
As the comet heads toward the sun the ice melts, leaving a bright tail of gas and debris which can be millions of km long, that is what’s seen from Earth
What is light years?
The distance that light travels through a vacuum (like space) in one year
Light travels= 300 000 km/s
So 1 light year= 9 460 000 000 000 km
Light year is a measurement of DISTANCE not time
What is a Parallax?
When something appears to move when you look at it from different places.
The apparent movement of the star between the two photos (6 months) lets you work how far away it is.
Stars further away tend to move less
Brightness of stars
Astronomers know much much EM radiation (electromagnetic radiation) certain types of stars actually emit, so you can tell how far away they are from Earth
Atmosphere and light pollution
The atmosphere absorbs quite a bit of light coming from space before it reaches us.
Light pollution makes t hard to see dim objects
That’s why scientists use the Hubble Space Telescope in space
EM radiation
It travels fast
Why are distant galaxies moving away from us?
When a galaxy us moving away from us the wavelength of light from it changes = RED SHIFT
By looking at how much red shit there is you can tell how quickly it is moving away .
The more distant the Galaxy, the faster it moves away from us, providing evidence that the universe is expanding
Big Bang Theory
A big explosion that caused the galaxies to move away from each other at great speed from a single point.
Due to the universe being compressed into a very small space, then it exploded and started expanding and the expansion is still continuing.
Difficult to tell how much the expansion has slowed down
Wegener theory
Continental drift= the earth is slowly drift apart, the continents fit together like a puzzle
The movement of continents could be caused by tidal forces and the earths rotation
Why was Wegener’s theory not accepted?
- couldn’t explain by the ‘land bridge’ theory
- the explanation of how the drifting happened wasn’t convincing
- the movement wasn’t detectable
- other geologists thought it was impossible
- he wasn’t a geologist himself but a meteorologist
New evidence of continents drifting
The Mid-Atlantic ridge, the magma rises up through the sea floor.
-when it solidifies and forms underwater mountains that are roughly symmetrical either side of ridge. This suggests that the sea floor is pressing by a few cm per year.
• magnetic orientation of the rocks, as the magma erupts out of the gaps, iron particles in the rock tend to align themselves with the earths magnetic field. Every half million years or so the earths magnetic field swaps direction and the rock on either side of the ridge bands of alternate magnetic polarity, symmetrical about the ridge
S-waves
Only travel through Solids
Slower
TranSverse
