What is the Universe?
- Stars and planets form from interstellar
- Edwin Hubble
Played two sports and earned two degrees
Attended oxford and law school
Drafted for ww1
First person to see other galaxies
Developed a classified galaxies
Explained redshift
Defined the big band theory
Redshift depends on distance from earth
Further away an object is, the faster it is moving away
Big Bang theory
Boom, then expansion
Steady State Theory-Fred Hoyle
New matter has been created when space becomes available
Motion in Space
- perihelion=closest to
- aphelion= farthest from
- Farther a satellite,
- longer to complete orbit
- greater the distance it will travel to complete the orbit
- the slower its average speed of motion
- Newton's Laws
- an object in motion will stay in motion unless acted upon
- an object accelerates in the same direction of the force applied
- for every action, there is an equal and opposite reaction
- Newton+Kepler= :*
- parallax=an apparent change in the direction of an object, caused by a change in observation position that provides a new line of sight
- Precession= earth's wobble on its tilted axis
- takes earth about 26,000 years to wobble
- Nutation=messed with earth's tilt
Barycenter= balance between 2 things
The Moon
Nutation- tilt of the axis
procession- wobble of the axis
barycenter of the sun/earth is in the sun
procession- wobble of the axis
barycenter of the sun/earth is in the sun
- What makes our moon weird?
- large compared to what it orbits
- great distance from earth
- rocky solid composition
- no atmosphere, really hot and cold, 127 and -173 C
- No erosion
- high and low elevation
- similar mineral content
- capture theory- gravity pulled it in
- simultaneous formation- formed at same time, same composition
- impact- Mars-sized object collided and moon broke off
- ellipse, tilted at about 7*
- moon day and year are both 27.3 days
- this is called synchronous rotation, meaning that the same side of the moon is always facing Earth
- this is called synchronous rotation, meaning that the same side of the moon is always facing Earth
- far side of the moon is never seen from Earth
- when the moon's shadow hits Earth or Earth's shadow hits the moon
- solar and lunar eclipses, named after what is being blocked from Earth
- Umbra= darkest and smallest part of the shadow; cone shaped (total darkness)
- Total solar eclipse= only people in the umbra experience a total solar eclipse
- partial solar eclipse= in the penumbra, since the sun is still partially visible, not safe to look at it
- During a full moon, the Earth blocks the sun's light from reaching the moon, making it appear dark
- Total lunar eclipse= moon is in the earth's umbra
- partial lunar eclipse= moon passes partly into earth's umbra
- moon's gravity pulls earth's water toward itself and away from 2 opposite places, creating low tides
- all 4 tides rotate in a 25 hour cycle
- spring tides happed twice a month, full and new moon
- combined force of the sun and moon's gravity make a tide with the most intense high and low tide
- neap tides happen twice a month, 1st and 3rd quarter