ASTR PTYS 206 Exam1 Review
ASTR/PTYS 206 EXAM 1 STUDY GUIDE Terminology
Astronomical Unit - Average distance from the Earth to the Sun
Centrifugal force - the tendency of rotating object to flee from the center of their rotation
Obliquity - tilt of a planet’s axis
Ecliptic - a plane in space defined by Earth’s orbit around the Sun; plane by which the orbit of all other planets in the solar system are compared
Inclination - angle between plane of orbit and ecliptic plane
Transit - passing of object in front of star, transit of planets can only occur on line of nodes; transit of Venus will occur next year and will not occur again until 2117
Prograde - Normal orbital motion, right hand rule (counterclockwise)
Retrograde - Reverse normal motion (clockwise)
Eccentricity - degree of elliptical shape of orbit compared to a circle
Sidereal - with respect to fixed point in space, e.g. length of day with respect to distant stars
Synodic - with respect to another object, e.g. length of day with respect to Sun
Doppler Effect - change in wavelength due to moving toward or away from observer; with sound lower pitch means moving away, higher pitch means moving toward; with light red shift (longer wavelength) means moving away, blue shift (shorter wavelength) means moving toward
Spin-Orbit Resonance - when rotation and orbit of an object around another body is in a simple ratio; caused by tidal dissipation; Mercury & Sun = 3:2, Moon & Earth = 1:1
Tidal Dissipation - when the gravity of two objects in orbit cause one to decelerate the other
Oblate Spheroid - shape of squashed sphere created by planet’s rotation
Precession - the movement of the axis of a spinning body, a wobble in its rotation; changes north star from Polaris to Vega on 26,000 year timescale; will not change degree of obliquity only direction of obliquity; with Earth caused by gravity of Sun and Moon pulling on the non-spherical shape of Earth
Nutation - Change in obliquity of a planet; changes Earth’s tilt from 22.5° to 24.5°; results
Astronomical Unit - Average distance from the Earth to the Sun
Centrifugal force - the tendency of rotating object to flee from the center of their rotation
Obliquity - tilt of a planet’s axis
Ecliptic - a plane in space defined by Earth’s orbit around the Sun; plane by which the orbit of all other planets in the solar system are compared
Inclination - angle between plane of orbit and ecliptic plane
Transit - passing of object in front of star, transit of planets can only occur on line of nodes; transit of Venus will occur next year and will not occur again until 2117
Prograde - Normal orbital motion, right hand rule (counterclockwise)
Retrograde - Reverse normal motion (clockwise)
Eccentricity - degree of elliptical shape of orbit compared to a circle
Sidereal - with respect to fixed point in space, e.g. length of day with respect to distant stars
Synodic - with respect to another object, e.g. length of day with respect to Sun
Doppler Effect - change in wavelength due to moving toward or away from observer; with sound lower pitch means moving away, higher pitch means moving toward; with light red shift (longer wavelength) means moving away, blue shift (shorter wavelength) means moving toward
Spin-Orbit Resonance - when rotation and orbit of an object around another body is in a simple ratio; caused by tidal dissipation; Mercury & Sun = 3:2, Moon & Earth = 1:1
Tidal Dissipation - when the gravity of two objects in orbit cause one to decelerate the other
Oblate Spheroid - shape of squashed sphere created by planet’s rotation
Precession - the movement of the axis of a spinning body, a wobble in its rotation; changes north star from Polaris to Vega on 26,000 year timescale; will not change degree of obliquity only direction of obliquity; with Earth caused by gravity of Sun and Moon pulling on the non-spherical shape of Earth
Nutation - Change in obliquity of a planet; changes Earth’s tilt from 22.5° to 24.5°; results