P1 - The Earth in the Universe Flashcards
How old is the Earth?
4500 million years old.
How old is the Solar System?
5000 million years old.
How old is the Universe?
1400 million years old.
How many years older is the Sun than the Earth?
500 million years older.
Can you name the 6 ways scientists can use rocks as evidence of the Earth’s age?
- Erosion - Compacted layers, produced by weathering and erosion. Older layers at the bottom.
- Craters - Evidence on Moon, not on Earth due to erosion.
- Mountain formation - If new mountains weren’t being formed, the Earth’s surface would have eroded down to sea level.
- Folding - Folding rocks requires huge force over a long time.
- Fossils - Shows how life has changed.
- Radioactivity - Lower radioactivity means older.
What is the Earth’s core made from?
Nickel and iron.
How is the Earth’s core still hot?
From the decay of radioactive elements.
Why was Wegener’s theory not immidiately accepted?
- He wasn’t a geologist, and was seen as an outsider.
- The supporting evidence was limited.
- It could be explained more simply. e.g: A bridge connecting continents could have eroded over time.
- The movement of the continents wasn’t detectable.
What is a geohazard?
A natural hazard.
How often does the Earth’s magnetic field change polarity?
Every million years.
Which plate is denser? Oceanic or continental?
The Oceanic plate is denser.
How are metamorphic rocks formed?
When due to extreme heat, the minerals in sedimentary or igneous rocks are changed chemically.
They do not melt however, that would form an igneous rock.
If a wave is travelling at a constant speed…
If frequency increases, the wavelength will _________.
If frequency increases, the wavelength will decrease.
and vice-versa (If frequency decreases, wavelength will increase).
If a wave is travelling at constant frequency…
If the wave speed decreases, the wavelength will _________.
If the wave speed decreases, the wavelength will decrease.
and vice-versa (If wave speed increases, the wavelength increases).
What are the units for wave speed?
m/s.
What are the units for frequency?
Hz.
What are the units for wavelength?
m.
What are the units for distance?
m.
What are the units for time?
s/secs.
How was the Solar System formed?
- The solar system started as dust and gas clouds, pulled together by gravity.
- This created intense heat and nuclear fusion began, hence a star was born! That’s the sun by the way…
- The remaining dust and gas formed smaller masses, which were attracted to the sun.
Name the 5 smaller masses of our solar system.
- Planets.
- Moons.
- Asteroids.
- Comets.
- Dwarf planets.
Compare asteriods and comets.
Asteroids are rocky and comets are icy.
What shape are orbits?
They are elliptical.
Comets are highly elliptical.
What is the speed of light?
The speed of light is 300,000km/s through space (a vacumn).
How does relative brightness work?
Further away stars are dimmer.
However, brightness can vary so a star’s distance is never certain.
How does Parallax work?
Stars in the distance appear to move against the background of distant stars. Closer stars appear to move more through parallax.
In Parallax, two measurements are taken - an initial measurement and another 6 months later (e.g: Jan - July) to try and get the actual position of a star using the opposite sides of orbit.
You are measuring the parallax angle. Greater distance = Smaller parallax angle.
However, the further away a star, the less accurate the measurement is.
How long does it take for light to reach Earth from the Sun?
Rougly 8 minutes.
Explain how Hubble’s Law works.
Hubble’s Law states:
“The speed at which a galaxy is moving away is proportional to its distance from us”
If all of the galaxies are moving away from us, then this must mean that the Universe is expanding.
-
Sources of light further away from us have a longer wavelength, and are red shifted.
Wavelengths of light from nearby galaxies are longer than scientists expect, which means they must be moving away from us.
The Universe keeps expanding when there isn’t enough mass.
What will happen if there is too much mass?
Gravity will put everything back together and the Universe will collapse.
What are the 3 layers of the Earth called?
- Crust.
- Mantle.
- Core.
Explain Seafloor Spreading.
Seafloor Spreading is where convection currents in the mantle cause magma to rise. These currents move the solid part of the mantle and the tectonic plates.
When the plates move apart, magma reaches the surface and hardens, forming new areas of oceanic crust (Seafloor) and pushing the existing floor outwards.
New crust is continuously forming.
Compare P and S waves.
P-waves are Longitudinal.
S-Waves are Transverse.
(Cloest in alphabet).
The fastest wave: P-Waves (_P_hast).
The slowest wave: S-Waves (_S_low).
Solid only wave: S-Waves (_S_olid).
The first wave: P-Waves (_P_rimary).
The second wave: S-Waves (_S_econdary).
Label the wave below.
What types of radiation do stars produce?
- Visible light.
- Ultraviolet.
- Infrared.
As stars get further away, their wavelength of visible light gets ________.
As stars get further away, their wavelength of visible light gets larger.
How much of the Solar System’s mass is the Sun?
99%.
What is the heaviest planet?
Jupiter.
What planet has the largest orbit?
Neptune.
Why is the fate of the universe difficult to predict?
Because we can only measure the mass of those parts of the Universe which emit radiation and radiation travels such a long way to get to us, so precise measurements can not be made.
What is the principal frequency?
What factor causes it to increase?
Radiation with the greatest intensity.
Heat causes it to increase.
