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Astro100 MT uofr
university of Regina Astronomy 100 - martin beech
| Term | Definition |
|---|---|
| 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
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