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Astro100 MT uofr

university of Regina Astronomy 100 - martin beech

North Celestial Pole stars move in a circle around this point due to Earths rotation. Polaris(North star)
Basic Things(moon, sun , earth) Sun=1 year= 365.25 days Earth = 24hours = 360degrees Moon = 29.530 days = moon cycle
Planisphere Projection of the celestial sphere onto a flat disc
Celestial Sphere An imaginary sphere of which the observer is the center and on which all celestial objects are considered to lie
Celestial Equator The projection into space of the earth's equator; an imaginary circle equidistant from the celestial poles.
Ecliptic The ecliptic corresponds to the projection of the Earth's orbit onto the celestial sphere
The Metonic Cycle It is the time for the Moon to show the same phase in the same position on the sky. 235
Angular Size physical size if distance is known
Angular Units and Conversions 360 degrees in a circle 60 arc minutes in 1 degree 60 arc seconds in 1 arc minute
Speed of Light c = 3 x 10 to the 8 m/s
Speed formula Speed = Distance Traveled/time taken
Light Year The distance traveled by a light ray in 1 year
Nearest Star Proxima Centauri
Astronomical Unit Average distance between the Earth and the Sun 1 AU = 1.496 x 10 to the 8 km. Distance can be directly measured by radar.
Superior Planet A planet with an orbit greater than Earth's (Mars -> Neptune)
Inferior Planet A planet with an orbit smaller than Earth's (Mercury and Venus)
Conjuction Planet is directly lined up with the Sun as seen from the Earth
Oppopsition Sun and planet in line with Earth, but in opposite directions (180degrees apart) on the sky(as seen from Earth)
Elongation The angular seperation of a planet from the sun
Method of Copernicus Theory : At greatest elongation the observers line of sight is tangential to the planets orbit Deduction: Can determine the size of the orbit relative to Earth's by measuring the greatest elongation
Johannes Kepler Assistant to Tycho Brahe became mathematician to Emporer Rudolph
Kepler's 1st Law The planets revolve around the Sun along elliptical orbits with the Sun at one focus
Kepler's 2nd Law A line drawn from the planet to the Sun sweeps out equal areas in equal time. Equal area Equal time traveled
Eccentricity(e) Describes shape of the ellipse. For a closed orbit 0 < e < 1
Perihelion Closest point to the Sun
Aphelion Greatest distance from Sun
Eight of 13 published in Harmonice Mundi as number 8 in a list of 13 points
Kepler's 3rd Law The square of a planets orbital period (P) is proportional to the cub of its orbital semi-major axis. P^2=K * a^3. If p(years) and a(AU0 then k = 1
Newton's Genius Hypothesis: there is a gravitational attraction between all of the planets and the Sun
Newton's 1st law of motion A body will remain at rest or in constant motion along a stright line path unless acted upon by an external force
Kepler's 3rd Law with Newtons help P^2/a^3 = K = 4pi^2/G(Msun + Mplanet)
Conditions for Planetary Status 1. Object must orbit the Sun 2. Large enough to be spherical through its own gravity 3. Must have 'cleared' its region of the solar system of other (smaller) objects.
Dwarf Planets An object that satisfies conditions 1 and 2 for the planets but not condition 3
Main components of the Solar system -Sun -Planets(Terrestrial Plants and Jovian Planets)
Terrestrial Planets Small, rocky(metal core) worlds with orbits less than 2 AU for the Sun (Mercury ->Mars)
Jovian Planets Large, mostly gas-giant planets with orbits greater than 5 AU from the Sun (Jupiter -> Neptune)
Oort Cloud Vast resevoir of comets surrounding Sun(spherical halo of objects) COmets can enter the inner solar system at any angle
Kuiper Belt disk like distribution of large ice/rock objects
Minor Planets Rock/metal, with sizes less than 1000km
Comets Mostly water-ice, with sizes less than 50km. Long elliptical orbits at any angle to ecliptic
Kuiper Belt Objects ice and rock, with sizes up to several 1000km
Main belt Asteroids Near circular orbits about the Sun, located between Mars and Jupiter, there are more small than large, population evolved through collision
Meteorites 1.Are small(meter sized) fragments of material(rock&iron) ejected from the surface of asteroids during collisions 2. Survive passage through Earth's atmosphere to be collected on the ground 3.Tell us about the composition of Astoids and 1st mats to form
Meteors-shooting Stars Centimeter(and smaller) sized grains (derived from comets) that are totally destroyed during their passage through Earth's atmosphere
Comet Nucleus water ice+embedded rocks+dust and organic compounds. Typically a few kilometers in size. become active when approaching sun approx. 1.5 AU. Ice sublimation (ice to gas) produces tails. Comet tails point away from the sun.
Coma Bright spherical halo-sunlight reflected off gas and dust particles
Type 1 Tail/ plasma tail Blue colour - emission from ionized CO molecules-interaction with Sun's magnetic field
Type 2 Tail/ dust tail Sunlight reflected off small dust particles
Plutinos Numerous smaller objects that follow Pluto
Reflecting Telescope light captured by a curved mirror
Radio Telescope Light captured by a a curved metal mirror
Refracting Telescope Light captured by a curved glass lens
Telescope a telescope is a device for collecting and bringing to a detector electromagnetic radiation eg. light
Electromagnetic Wave a disturbance propagated as a variation in the local electric and magnetic fields at the speed of light
Wave a wave is a travelling disturbance
EM waves equation c = lamda * f
starlight how stars tell us about themselves
Doppler Effect Pitch increases as vehicle approaches and decreases as it moves away - the change is an apparent change - not a change in the siren's actual tone
Doppler's Formula (lamdaobs - lamda)/lamda = V/c = Velocity/speed of light
Synodic Period The orbital period is the time taken for a given object to make one complete orbit about another object
The big result d(km) = (2pi/360)D(km)alpha(degrees)
Expanding orbit formula Delta = c(t2 - t1)/2
Hubbles Law There is a systematic increase in the velocity of recession of a galaxy with increasing distance
Hubbles Formula Vgal = H * Dgalaxy
Radiant energy formula E = h * f
Created by: davidvachon1