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 ...

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