My Notes for Unit 2 Flashcards
What are exoplanets?
Planets around other stars
How many exoplanets have been discovered? How many probably exoplanets are there?
1) 1000
2) 2000
What are the 2 dominant forces in our universe?
1) gravity (attractive force–accretion)
2) Thermo-nuclear energy(repulsive force–explosion) –> fission or fusion
What is the composition of the universe?
The universe as a whole is mostly Hydrogen
H=75%
He=23%
Li=2%
Most stars are mostly composed of__and__
H and He
What are the two major elements of which the Earth is made?
Iron and oxygen
The Earth: Fe= O= Si= Mg=
Fe=35%
O=30%
Si=15%
Mg=13%
Why doesn’t Earth have all H and He like stars?
Because of gravity. Atoms are always in motion
What is the largest star?
Canis Majoris
What are the four forces that control the universe?
1) Gravity
2) Electromagnetism
3) Strong nuclear force
4) Weak nuclear force
What are the smallest particles that exist within our universe?
quarks (they make up the protons and neutrons) There are three types of quarks and protons contain 2 of the 3 kinds and neutrons contain 2 of the 3 kinds.
What does electromagnetism involve?
electrons and their behaviour (electrons, protons at the scale of)
What is the strong nuclear force?
In nuclei of atom and holds quarks together
What is the weak nuclear force?
Holds protons and neutrons together
- formation fo atoms
- radioactive decay
What is the repulsive force of the resulting energy explosion with stars controlled by?
gravity
What are the oldest stars composed of? The youngest stars?
Oldest: H, He, Li
Youngest: have all 92 naturally occurring elements
___takes place with stars to create new elements.
Fusion
At what point does an average or small star stop producing elements?
At Carbon
When will will large stars stop producing elements?
At Iron
What happens when large stars start to produce iron?
-If it reaches the iron stage it becomes a supernova.
Large stars become:…?
- neutron star
- black hole
- dead star
What is a black hold?
Any light produced can’t escape because gravitational force is too strong.
What is a single particle of light called?
a photon
At what point are the rest of the heavy elements created?
supernova
Stars are___factories.
elements
What is stardust?
the stuff in a supernova
What happens at the end of a small star’s life?
once they have been producing C for awhile they inflate because of carbon production of elements because they produce more energy that He does from H. Gravitational energy can’t hold on and outer protons of stars take off. He and He may blow away leaving carbon core (diamond star) –> dead star aka a White Dwarf.
What is an active star?
Nuclear fusion takes place and energy is created.
Nuclear fusion + gravity =
star
What is a dead star?
What happens when stars die
Nova =
small star
Supernova=
large star
What are new stars created from
It is from the exploded gas and dust of a supernova
Our universe and our galaxy contains___stars, ___stars, and ___stars along with___.
- old
- new
- dead
- stardust
What does the birth of stars go back to?
The Big Bang
What is the Nebular hypothesis?
Every bit of matter melts and cools. Many things become solid particles. Form of vapour (H and He) (condensation). Supernova dust mingles. When two dust particles come together 9electromagnetic energy) they cling together. Gravity adds more and more dust (accretion)
When did condensation begin for our universe?
8 Ga
When did accretion begin for our universe?
4.7 Ga
When did accretion end for our universe?
4.55 Ga
What happened to most of the accreting dust?
It sunk to the central part (the sun) because of gravity.
In what way are (exo)planets in a state of dynamic balance?
- gravitational attraction to Sol
- centrifugal force outward generated b y spin evolution around its sun.
Galaxies for___.
clusters
1 ly = ___km
9X10^12
How many Ma does it take for the sun to make 1 revolution around the Milky Way Galaxy?
250 Ma
How many times has the sun gone around the MWG?
20.5 times
What is dark matter?
material in universe that is invisible to our eyes but has mass creating gravitational attraction that moves objects we can see. 5X as much of that in terms of its mass as there is n stars galaxies, etc.
-Attractive force pulling things together.
What percent of the universe is matter?
4.6%
What percent of the universe is dark matter? What does it do?
23% and it helps hold things together
What percent of the universe it dark energy? What is it?
- 72%
- Repulsive energy that we can see the effect of. Pushes clusters of galaxies apart. Causes the universe to expand.
What is the relationship between heat and atomic vibration?
Heat=atomic vibration
-The faster atoms vibrate, the more heat
What happens to the temperature when the atomic vibration goes up?
the temperature goes up
What is Earth’s internal heat?
self-regulated through nuclear fission (radioactivity)
What are the two parts to the Heat of Accretion?
1) Particles in mass of dust forming planets create heat as they smash together
2) Pressure generates heat as well –> pressure of stuff on EArth’s surface.
What is light a part of?
Is part of the electro-magnetic force (emf) spectrum.
What does light travel in?
travels in waves
Light: constant velocity in a___. ~___km/sec
- vacuum
- 300 000
How long does it take for light fro the sun to get to us?
8 min
Short waves:___frequency of waves.
high
Long waves: ___frequency of waves.
low
True or False: Light waves travel at the same speed?
true
What is spectroscopy?
The analysis of electromagnetic waves…esp. light waves.
How do you know the composition of a planet’s atmosphere?
The light emitted by an object is controlled mostly b the chemical composition of the object. Numerous other features can also be determined, such as “the doppler effect”.
What is the Doppler Effect?
You can measure the frequency of waves that bounce back
What is the red shift?
When an object (star) moves closer to the red end of things. You can identify velocity by the spin rate.
What is this refer to: Stretching and compression of electromagnet energy waves and sound waves…any energy that travels in waves.
The Doppler Effect.
The Big Bang: Velocities increasing___Ga after this happened.
13.8
When did the MWG begin?
b/w 7-8 billion years ago from exploding stars.
Density=
mass / volume (grams / cubic centimetres)
How can astronomers figure out the density of stars?
Depending on the way it spins because the make-up of something can control the way it spins.
What are the two things that density is controlled by?
1) what it’s made of
2) how large the object it (because more weight pushes down)
How long does it take the Earth to spin once?
23 hours and 56 minutes
Why isn’t the Earth a perfect sphere?
because it’s spinning which creates a centriphical force which makes it ‘blob’ at the equator
What is elliptic?
- planet of orbit around the sun
- elliptical orbits are mostly circular
What is escape velocity?
How fast something has to move to escape a planet’s gravitational attraction.
The larger the mass, the larger the___attraction.
gravitational
What are volatile elements?
anything that will boil away easily. Will either be boiled off or you get a solar wind.
What gave us our current distribution of planets?
collision of planetesimals
What two kinds of objects does the Kuiper belt contain?
1) dwarf planets
2) comets
What are dwarf planets?
Stay put and orbit then. Of low density. A lot of ice.
What are comets?
Smaller objects like asteroids except they seem to be composed of a mixture of dust, water ice, and CO2 ice. Travel around the sun, some in elliptical orbits. Comets from Kuiper Belt are making orbit around the sun every 1-4 years.
What is the largest dwarf Planet?
Eris
Do all dwarf planets have moons?
no
What dwarf planet is the furthest away?
Sedna
What did all dwarf planets form from/
All formed by accretion of dust and gas that eventually formed the sun (left over objects that didn’t make the sun)
What did asteroids form from?
left over objects that didn’t make planets
Gas giants may have a core similar to that of the___.
Earth
Besides the Kuiper Belt, where else can comets come from?
Oort Belt
What is gas around a comet caused by?
Solar wind that vaporizes i.e. and causes it to stream into space of billions of meters.
We know of___moons.
71
Why doesn’t our moon have a layer of ice around it?
Because of its proximity to the sun
How did moons (besides our sun) form?
From accretion
What do some of the smaller moons seem to be?
asteroids or comets trapped by gravitational pull of planets.
What is our moon believed to be?
Our moons seems to be mad elf Eartha and possibly some of the planetesimal that slammed into Earth.
What does the direction of the streak behind a comet show?
direction of comet
What is the streak behind a comet caused by?
Solar wind tha tis shed off the sun
What does the solar wind create? What is it composed of?
- creates a kind of electromagnetic energy
- Composed of stream of electrically charged particles and light
What are northern and southern lights caused by?
solar wind
What do we see of a comet?
the material being shed off of it
Why does a comet glow?
Because of the electric particles of the solar wind.
Solar wind drives material___from objects.
away
Where do meteor showers take place?
in upper atmosphere
What are the meteors that we see in the showers?
The rocky dust from comets.