ASTR 1010 1st EditionLecture 23Outline of Last Lecture I. CometsII. AsteroidsIII. MeteorsOutline of Current LectureI. ReviewA. DefinitionsCurrent LectureI. ReviewA. Definitions1. Aphelion: the point at which an object is furthest from the sun.2. Perihelion: the point at which an object is closest to the sun.3. AU: Astronomical Unit; average Earth to Sun distance (93 million miles)4. Geocentric Model: Ptolemy believed universe revolved around the Earth. Attempted to explain retrograde motion.5. Heliocentric Model: Copernicus believes the Sun was the center.6. Wavelength: distance between points of the same phase in adjacent waves. 7. Frequency: number of crests or cycles passing a point per unit8. Period: 1/frequency or 1/f9. Speed: Wavelength x frequency10.Electromagnetic Spectrum (In order of increasing frequency):- Gamma- X-Ray- UV- Visible (red, orange, yellow, green, blue, violet)- Infrared- Radio11.Newton’s Laws:- Any object in motion will stay in motion unless acted upon by an unbalanced, outside force.- Force = mass x acceleration- Every action has an equal and opposite reaction.12.Kepler’s Laws:- The orbit of each planet is an ellipse with the sun at its focus- As the planet moves around in its orbit, it sweeps out equal orbits in equal time- More distant planets orbit the sun at slower average speeds, obeying the relationship p2=a313.Newton’s Universal Law of Gravitation:- Every mass attracts every other mass- Attraction is directly proportional to the product of their masses.- Attraction is inversely proportional to the square of the distance between their centers.- Formula:
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