CHap-16..The solar system
->In 1957(Oct. 4th-my birthday :)), the first artificial satellite(SPutnik) was launched.
16.1THE PLANET EARTH
->The Solar system isa made up of nine planets(incl. Earth) and their dozen or so satellites, plus thousands of asteroids and countless comets and meteroids.
->Earth is going thorugh two simultaneous motions:
-->(1)Daily rotation of earth on its axis
-->(2) the annual revolution of Earth around the Sun

->The earth revolves eastward around the sun and sweeps ut a plane called the orbital plane of earth.
->This motion of Earth produces an apparent WESTWARD motion of the Sun on the Celestial spehere.
->ECLIPTIC=The apparent path of the Sun on The celestial sphere
->The earth is rotating eastward around a central internal axis that is tilted 23.5 from a line that is perpendicular to the orbital plane of the Earth. This causes seasonal changes on earth
->ROTATION = When a mass spins on its axis
->REVOLUTION = Movement of one mass around another

EXPERIMENT TO SHOW ROTATION OF EARTH
->(1)FOUCAULT PENDULUM = Set up near the north or south pole for clearer results.
-->A 200 ft. Pendulum with an iron ball attached at the end. FIne grain of sand on the floor which can be slightly furrowed by sharp needle.
-->Someone starts the swinging by swinging it with a strong fine thread. ensure no lateral movement.
-->Start 24hr. clock.After few minutes, the plane of swinging pendulum appears to be circular.
-->After an hour 15Degrees clockwise rotation.
-->After 6hr., 90 degrees clockwise(parallel with ceiling)
-->After 24 hrs...it apparently toates 360 degrees
-->We can also see the rotation by seeing that the pendulum stays on the same plane, by correlating its position with taht of the stars.

PROOF OF REVOLUTION OF EARTH
->PARALLAX = The apparent displacement of a star thata is located fairly close to earth. with respect to more distant stars/
->As the Earth revolves round the sun, there is an apparent shift in the positions of nearby stars in respect to the stars that are farther away because of the motion of the Earth
SECOND PROOF
->ABERRATION OF STARLIGHT = apparent displacement in the direction of light coming ffrom a star owing to the orbital motion of the Earth

->The great distance to stars is measured in Parsecs(Parallax +second)

->1 PARSEC = The distance to a star when the star exihibits a parallax of one second
->The Earth's density is 5.5g/cm^3
->Earth's circumference formula =
Circumference = dist. syene to Alexandria
_____________ _________________________
360(degrees) 7.5(degrees)

16.2 SOLAR SYSTEM
->Initially, GEOCENTRIC THEORY = Earth is the center of the Universe
->Faults(other than the obvious)=(1)Failure to explain the varriation of brightness of the planets at different times of the year
(2)Failure to explain the motion of some planets
->HELIOCENTRIC THEORY = Sun is at the center

->KEPPLER'S 1ST LAW = LAW OF ELLIPTICAL PATHS:
--> All planets move in elliptical paths around the Sun with the Sun at one focus of the ellipse.

->KEPPLER'S 2ND LAW = LAW OF EQUAL AREAS
--> An imaginary line (radius vector) joining a planet to the Sun sweeps out equal areas in equal periods of time.

->KEPPLER'S THIRD LAW = HARMONIC LAW
-->The ratio of the sqaure of the period and the cube of the semimajor axis (one-half the larger axis of an ellipse) is the same for all planets.
FORMULA = period^2 = Constant
________
Radius^3
->NEWTON'S HARMONIC LAW
--> Period^2 = 4(pie)^2
_______ ________
Radius^3 Gm(sun)
G=Gravitational constant
m = mass of sun

CLASSIFICATION
->SUPERIOR PLANETS = Those planets whose orbits are greater than Earth's
->INFERIOR PLANETS = Those planets whose orbits are smaller than Earth's
->TERRESTRIAL PLANETS = PLanets resembling Earth. Mercury, Venus, Earth and Mars
->JOVIAN PLANETS = Planes resembling Jupiter.Jupiter, Saturn URanus Neptune
->PLuto unlike either, and some consider it an asteroid

->ASTRONOMICAL UNIT(AU) = Mean distance from earth to sun (9.3 X 10^7mi.)

ORBITAL REVOLUTION PERIOD
->SIDEREAL PERIOD = The time interval between two successive conjunctions of the planet with a star(planet and star on the same meridian) as observed from the sun
->SYNODIC PERIOD = The time interval between two successive conjunctions of the planet with the Sun(planet and Sun on the same meridian) as observed from Earth

->OPPOSITION
-->Term used to describe the position of a planet when the planet is 180(Degrees) from the Sun. That is, Planet is on the opposite side of the Earth from the Sun

ASTEROIDS
->CERES = Slightly oer 600 mi in diameter, has an orbital perriod of 4.6 years.
->ASTEROIDS = 2000+ objects (named & numbered) orbiting the Sun between Mars and Jupiter
->Only Vesta can be seen with unaided eye
->Mostly Spherical, some rod shaped, some irregularly shaped
->They all revolve counterclockwise around the sun
->Asteroids are presently believed to be early solar system material that never collected into a single planet
->Chiron has a very elliptical orbit and may eentually collide with a planet or be ejected from the solar system.