The Wonders Of Astronomy

Some Formulas: a) Powers of Ten: 1 = 100 ; 1,000 = 103 ; one million = 1,000,000 = 106

; one billion = 109 ; 0.001 = 10-3 ; 0.000001 = 10-6 ; ... etc "nano-"(n) = 10-9

"micro-"(m) = 10-6 "milli-"(m) = 10-3 "kilo-"(k) = 103 "mega-"(M) = 106

b) Geometry: Circles: Area = pr2

Perimeter = 2pr

Spheres:

Volume = 4/3pr3

Surface Area = 4pr2

c) Laws of Motion:

Time = Distance/Speed or Distance = Rate x Time

1 Year = 3.16 x 107 sec

1 AU = 1.5 x 108 km

1pc = 3.26 ly = 206265 AU

d) Kepler's and Newton's Laws: P2(yr) = a3(AU)

F = ma

FG = Gm1 m2 / r2 e) Light, Waves:

Speed of light c = 3 x 105 km/sec = 300,000 km/sec = 186,000 miles/sec f) Telescopes:

Light Gathering Power -> Area g) Magnification = (Focal length of the Objective) /

(Focal length of the Eyepiece) General Knowledge: COVER ALL THE TOPICS IN THE SYLLABUS! *

Who were Aristotle, Eratosthenes, Ptolemy, Galileo, Kepler and Newton and what were

their main contributions to science?

Aristotle (350 BC)

Greek Philosopher

Believed the Earth is at the center of all orbits

Geocentric System

Eratosthenes (200 BC)

Greek astronomer and mathematician

First to measure the Earth?s diameter

Ptolemy (140 AD)

Retrograde Motion - Planet appears to be moving backwards from the view of the Earth.

Theory of Epicycles - a small circle, riding on a larger circle called the deferent, on

which a planet moves. The epicycle is used to account for retrograde motion.

Heliocentric System

Galileo

Credit for first using a telescope to make astronomical studies

Observed the moon

Observed that the apparent size of Venus changes for different phases

Studied projectiles

Dropped two balls from one point and discovered they fell at the same speed. Arrested

and tried for stating that the Earth moved.

On his death bed said, ?Epur Si Muave? = It?s still moving.

Kepler ?Kepler?s Supernova?

Kepler?s Laws of Planetary Motion

The orbit of the planets are ellipses - NOT CIRCLES with the Sun located at one of the

focus of the ellipse. A line from the planet to the sun sweeps over equal areas in equal

intervals of time. Hence, the planet moves faster when closer to the Sun.

A planet's orbital period squared is proportional to its average distance from the Sun

cubed: P2 (years) = a3 (AU)

Newton

The Giant of the 18th Century

Most influential scientist to ever live

Explained Kepler?s Laws

Newton?s Laws of Motion

A body continues at rest or in uniform motion in a straight line unless acted upon by

some external force

A bodies change of motion is proportional to the force acting on it and is in the

direction of the force

When a body exerts a force on a second body, the second body must exert an equal and

opposite force back on the first body

Newton?s Law of Gravitation

The force is proportional to the PRODUCT of the masses. That is, the force with which,

say the Sun acts on a Planet, is proportional to the mass M1 of the Planet and to the

mass M2 of the Sun. The force is inversely proportional to the SQUARE of the Sun-Planet

distance r. If the distance between the Sun and the Planet is increased by a factor of

two, the force becomes 4 times smaller (weaker). The force is always ATTRACTIVE: the Sun

wants to "engulf" the Planet - it never pushes it away. G is a UNIVERSAL constant:

G=6.672x10-11 m3/kg/s2 It is the same for any two objects in the Universe!!!

Invented Calculus

* Constellation, the celestial equator, the ecliptic, the celestial poles, right

ascension and declination.

Constellation - One of the 88 areas into which the sky has been divided for convenience

in referring to the stars or other objects therein.

Celestial Equator - The intersection of the celestial sphere with the plane that passes

through the Earth?s equator.

Ecliptic - The path followed by the Sun across the celestial sphere in the course of a