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Astronomy Exam 1

Kepler's 1st Law of Planetary Motion Planet's orbit is an ellipse; with Sun at one focus
Kepler's 2nd Law of Planetary Motion Object orbiting Sun on elliptic orbit is FASTEST when CLOSEST to Sun and SLOWEST when FURTHEST from the Sun
Kepler's 3rd Law of Planetary Motion Periods (YEARS) are related to planets' orbital sizes (a in AU); applies to planets orbiting a 1 solar mass star p^2=a^3
Newton's 1st Law of Gravity body at rest/ motion STAYS in rest/motion UNLESS acted upon an outside FORCE
Newton's 2nd Law of Gravity F=ma (Force=mass x acceleration) more mass--more force to accelerate
Newton's 3rd Law of Gravity Every action has an EQUAL and OPPOSITE force
Occam's Razor Scientists should prefer the simpler of two models that agrees with the observations
scientific paradigm General pattern of thought that tends to shape scientific study for a specific time period
diameter of Earth 8,000 miles
circumference of Earth 24,900 miles
Average/Mean Earth-Sun distance 93.9 million miles (=1 AU)
1 light-year DISTANCE light travels in a vacuum in a year
right ascension (LONGITUDE) but on the celestial sphere [used in equatorial coordinate system]
declination (LATITUDE) but on the celestial sphere [used in equatorial coordinate system]
elevation angle number of DEGREES between the horizon and the object (AKA altitude, used in horizon coordinate system]
azimuth direction around the horizon from due north (used in horizon coordinate system)
ecliptic Sun's apparent annual path among the constellations (fundamental great circle of ecliptic coordinate system)
zodiac constellations on the celestial sphere through which the ecliptic passes
vernal equinox points at which the sun passes through the equator making the DAY AS LONG AS NIGHT (FALL & SPRING equinox)
celestial meridian circle that connects the zenith with the north and south poles
zenith straight UP from observer
nadir straight DOWN from observer
north celestial pole point on the celestial sphere directly above earth's north pole
latitude (on Earth) angular NORTH-SOUTH distance between Earth's equator and a location on Earth's surface
longitude (on Earth) angular EAST-WEST distance between Earth's prime meridian and a location on Earth's
What causes the seasons? Earth's 23 & 1/2 degree tilt on its axis
precession of the equinoxes slow change in direction of the axis of Earth's rotation
Pythagorus a^2+b^2=c^2
scientific method based on observation, logic and skepticism
Hypothesis collection of ideas that seems to explain a phenomenon
model hypotheses that have withstood observational or experimental tests
Theory a body of related hypotheses can be pieced together into a self consistent description of nature
laws of physics theories that accurately describe the workings of physical reality, have stood the test of time and have been shown to have great and general validity
Solar system planet order sun, mercury, venus, earth, mars, jupiter, saturn, uranus, neptune, pluto (no longer considered planet)
quasar light emitted from the mass falling into the massive black hole inside the center of a galaxy
angular distance between stars if you draw lines from your eye to each of the two stars, the angle between the two stars
Created by: daisy98