AST101 UofT

uranus

planet with weird axis tilt

venus

planet with opposite rotation

counter clockwise

direction planets rotate around the sun

terrestrial planets

relatively small and dense, rocky surfaces, lots of metals in its core. Usually no moons and no rings.

jovian planets

relatively large, has many moons. Mostly made of hydrogen, helium, and hydrogen compounds.

celestial poles

the points directly above the poles of the earth

celestial equator

forms a complete circle around the celestial sphere

zenith

the point directly overhead of the observer

lunar eclipse

this phenomenon occurs when earth lies directly between the Sun and the Moon

solar eclipse

this phenomenon occurs when the Moon lies directly between the Sun and the Earth

copernicus

the guy who proved that earth rotated around the Sun, but was not 100% accurate because orbits were elliptic, not circular

kepler

the guy who found out that the orbits of planets were elliptical and not circular

galileo

the guy who found out that orbit paths can be imperfect, and that things remain in motion unless a force acts on it

eccentricity

the quantity that describes how ellipse is stretched out from a perfect circle; the more it's stretched out, the higher eccentricity it is

orbital period

the time it takes for one astronomical object to complete an orbit around another one

orbital semi-major axis

the radius of the longer axis in an ellipse

kepler's three laws

1) orbit of each planet around the sun is elliptical
2) as planet moves around orbit, an imaginary line connects it to the sun sweeping out equal areas
3) more distant planets orbit the sun at slower speeds

newton's three laws

1) an object moves at constant velocity when no net force acting on it
2) force = ma
3) for any force, there exists an equal opposite reaction force

radiometric dating

a method in which we measure a rock's age by carefully measuring the rock's proportions of various atoms and isotopes (radioactive decay)

hydrostatic equilibrium

when gravity and gas pressure maintains the temperature and size of the sun

solar wind

the stream of charged particles spewed from the Sun

corona

the sun's atmosphere, extends several million km above the visible surface of the Sun. Temperature is incredibly high, around 1 million K

chromosphere

the middle layer of the Sun's atmosphere and the region that radiates the most UV light. Temperature only around 10,000 K

photosphere

visible surface of the Sun, less dense than Earth's atmosphere, and around 6000 K only. It has sunspots of intense magnetic fields

convection zone

where the energy generated in the solar core travels upwards by rising gas and falling of cooling gas, thus the word convection

radiation zone

where energy moves outwards as photons of light

core

the part of the sun at the very middle, where nuclear fusion transforms hydrogen into helium

proton proton chain

when two protons smash together, and then those particles smash together again, creating energy

sunspots

they look dark because they're not as bright compared to its surrounding. The sunpsots are regions with strong magnetic fields, and alter nergy levels in atoms so it causes spectral lines to split. They act as tight magnetic spots so it prevents surrounding plasma from entering the region, thus decreasing the temperature

doppler effect

phenomenon where objects travelling further away are red, and towards you is blue.

radiometric dating

the method of measuring a rockss age by its radioactive decay

frost line

after this points, planets were created from the seed of ice, whereas before, planets were created from seeds of rock and metals

nebular theory

the theory in which the solar system was once just stellar of cloud, that collapsed under its own gravity, and gave birth to the Sun in the center. Heated up bc of crashing particles, flattened because of spinning gas clouds, spinning as it shrank, and stopped it from being a black hole

formation of the Moon

must be a giant impact between Earth and a Huge planet .

counter evidence to nebular theory

reason why this cannot be the case, is because same observations around the universe, it would be weird if our solar system was an exception to the creation of other 'solar systems'

outgassing

this thing volcanoes do that build the atmosphere of terrestrial planets

greenhouse effect

visible light passes through the atmosphere. then, the surface absorbs the visible light, and emits thermal radiation in infrared. Greenhouse gases absorb and re-emit infrared radiation, heating the lower atmosphere.

carbon cycle

- atmospheric co2 dissolves in rain water
- rainfall erodes rocks on earth
- rivers bring minerals into ocean
- mineral dissolves and falls into ocean floor
- plate tectonics carries minerals into subduction zones
- it eventually melts and release co2
- goes into atmosphere through volcanoes

plasma tail

a comet tail that is ionized by UV light from the Sun and pushed outwards by solar wind, and is always extending directly away from the Sun

dust tail

dust size particles pushed outwards by the pressure of sunlight. slightly curved.

stony primitive meteorites

meteorites composed of rocky materials with little metallic flakes in it. created near frost line

carbon-rich primitive meteorites

meteorites composed of rocky materials but have carbon and sometimes, water. This means that these asteroids were composed near the outside of the asteroid belt,and near the frost line to create water.

metal-rich meteorites

meteorites made mostly out of high density iron and nickel, and are composed of terrestrial planet cores in composition

rocky processed meteorites

lower density rocks, made of mostly that of terrestrial mantles and crust, and are remarkably close to that of erupted terrestrial volcanoes.

origin of rings

small moonlets crashing into each other, creating fragments of moonlets rotating around the Jovian planet via accretion

tidal heating

Jupiter's moon undergoes this type of interior heating - it stretches sides of the planet so it heats up the interior through friction

orbital resonance

when multiple moons line up at the same time, creating an anomaly in gravitational pull strength.

extrasolar planets

planets around other stars like our solar system

transit

when a planet appears to move across the face of a star

transit method

the method of searching for eclipses by monitoring a star system's brightness over an extended period of time.

radial velocity

the velocity directed towards or away from us only

Fermi's paradox

1) we are alone
2) civilizations are common, but there has been no colonization
3) galactic civilization has not found us yet.

accretion

the process in which small particles condense from gas, into planetesimals

asteroid

minor planets left over from the birth of our solar system and are not big enough to become proper planets . Orbit closer to the Sun than comets

comets

chunks of ice mixed with rocky dust that were condensed in outer regions of the solar nebula.

Io

One of Jupiter's moons; the most volcanically active world in the solar system.

titan

moon of Saturn, made of mostly nitrogen

Doppler Method

A method of searching for gravitation tugs due to orbiting planets; it searches for a star's orbit movement around the center of the mass by looking for changing Doppler shifts in its spectrum. Used to look for big planets, and only close orbits.

transit method

a method in searching for planets by carefully monitoring a star's sytem's brightness over an extended period of time.Only works for edge-on orbigs, but can reveal smaller planets. gives you mass and size.

SETI

a collective term for scientific searches for intelligent life by monitoring radio signals from extra terrestrial civilizations

energy levels of atoms

a larger decrease of this will emit a high frequency of light