Astronomy

Alban Hoxhaj

SOLAR SYSTEM MODELS

GEOCENTRIC
 * Earth centered system developed by Ptolemy
 * Was accepted until the 1960's

Heliocentric
 * Sun centered system developed by Copernicus
 * Modern understanding of the structure of the Universe

Celestial Objects- Objects observed in the sky during the day or night. (planets, sun, moon, stars..) Constellation- A group of stars that make an identifiable pattern in the sky.

Rotation A spinning about the North and South Axis Evidence: The apparent daily counter- Clockwise motion of celestial objects around polaris (North Star) is because of Earth's rotation toward the East. (RATE= 15 degrees Per Hour)

Solar Day- The amount of time required for the Earth to rotate from one noon to the next. 15 degrees X 24 Hours= 360 degrees

CORIOLUS EFFECT Horizontal deflection undergone by all moving materials on the Earth's surface.

Northern Hemisphere- Deflected to the right (clockwise) Southern Hemisphere- Deflected to the left (counter clockwise)

Foucault Pendulum An experiment to demonstrate the rotation of the Earth.

REVOLUTION A Slightly Elliptical orbit around the sun (Counter Clockwise) 365.25 Days for one revolution Evidence: Seasonal change of the Constellations. The solar diameter varies in a cyclic pattern.

Perihelion- sun is the largest, occurs in the northern hemisphere winter (shortest distance between the Earth and Sun) Aphelion- Smallest, occurs in the Northern Hemisphere summer (largest distance between the Earth and Sun)

Seasons The Earth's tilt is 23.5 Degrees Parallelism of the Earth's axis- The Earth axis remains parallel throughout its revolution around the sun. Local Noon- When the sun reaches its maximum altitude. Zenith- The point directly overhead. (23.5 degrees North or South of the equator)
 * The sun's rays can only be directly overhead at solar noon between the Tropics.

Equinox- The sun is in the Zenith position at the equator (March 21 and September 23 or 21) 12 hours of both daylight and darkness.

Summer solstice- The sun is in the Zenith position at the Tropic of Cancer (June 21) Longest daylight of the year in the Northern Hemisphere.

Winter Solstice- The sun is in the Zenith position at the tropic of Capricorn (december 21) Shortest daylight of the year in the Northern Hemisphere.

Earth's Orbit 1.) Parallelism of Earth's axis- Every position of Earth's axis in it's orbit is parallel. 2.) Earth's distance to the sun at Perihelion- 147,600,000 KM at Aphelion- 152,400,000 KM 3.) a.) Planets travel in Elliptical Orbits therefore they will be at different distances from the sun throughout there revelotion. b.) The equal area law- States that each planet moves around the sun in such a way the an imaginary line joining the planet to the sun will sweep over equal areas of space in equal areas of time. c.) The Harmonic law- The Farther the planet is from the sun, the longer it's period of Revolution. 4.) Elliptical eccentricity A.) Eccentricity- Degree of the "Out of Roundness" of the ellipse. B.) Formula- Distance between foci divided length of major axis = eccentricity

The Planets and the Solar System 1.) Terrestrial (Inner) planets A.) Mercury, Venus, Earth, Mars B.) Consists of a rocky crust, a dense mantle layer, and a very dense core. C.) Average Density is above water D.) Iron, Silicon, Oxygen, and other heavy elements

2.) The asteroids that orbit between Mars and Jupiter divide the two groups 3.) Jovian (Outer) Planets A.) Huge, Gaseous, and much less Dense B.) Hydrogen and Helium C.) Have ring systems 1.) Centered around the planets equator 2,)Consists of many particles in independent orbits around the planet 4.) Meteroid- A rock or an icy fragment traveling in space 5.) Meteor- The light made by a meteoroid as it passes through earths atmosphere 6.) Meterorite- part of a large meteroriod that survives its trip through the atmosphere and strikes earth's surface

A.) 93% re stones (resemble earths dark igneous rocks but include 10-15% Iron) b.) Irons (85-95%The rest is nickel) C.) stony-irons ( rare mixture of stone and iron) 7.) the most abundant source of a meteroites is the ANTARTIC ice cap

Stars and Galaxies

1.) Distance between the earth and sun is 150 million km A.) 150 Mil. KM= Astromical Unit (au) B.) Lightyear (LY)= 9.5 X10 to the 12 Km/Yr Distance that a ray

Physical Properties of stars Size- range from smaller thanearth to 2000 x the diameter of the sun density - differs greatly mass most stars are fairly close to the sun'

Brighteness 1.) apparent magnitutde \- how bright

Luminosity- true brighteness of a star which depends only upon the size and temperature of a str Absolute Magmnitute- Expresses luminosity of stars as if they were seen from the sam distance.

3.) Origin of a star stars form from dense clouds of gas and dust an outside force troggers the attraction of gravity causing particles to move toward each other temperature increases as the area contracts If the cloud is large enough parts of it will start to glow Protostars- large glowing cloudd ections contraction continues protosstars become hotter and brighter the center cecomes so hot fusion begin ( Hydrogen nuclieunite t form helium)

4.) Red giants and supergiants star loses stability the stars gets so hot it causes the outer layers to expand, enlarging it surface area. the star radiates more light and appears brighter

5.) White Dwarfs Most of the fusion is used up Temperature and pressure of the core can no longer support the weight of its outside layers Glows faintly as it continues to cool

6.) Supernova As the star core cools it begins to collapse Pressure and temperature rise dramatically the star explodes violently

7.) black holes Gracitational forces are so powerful that even light can not escape

8.) Galaxy- a group of millions or billions of stars held together by gravity

9.) We belong to the Milky Way Galaxy 1.) Spiral- Center Lens shape and spiral arms which usually contain millions of stars as well as dust and gas. 2.) 15 billion years ago the mass exploded, forming and expanding cloud 3.) Cloud parts condenses into Galaxies.

Evidence is Red shifts or Doppler Effect

Earth's Moon 1.) The moon revolves in an elliptical orbit around the Earth A.) Revolution = 27.33 days B.) Perigee- Moons Nearest the Earth Apogee- Moon farthest the earth

2.) Phases of the moon A.) Two reasons - The moon is seen by reflected light - The moon is in orbit around the Earth

B.) Full Moon-

C.) Waning Gibbous-

D.) Last Quarter-

E.) Waning Crescent-

F.) New Moon-

G.) Waxing Crescent-

H.) First Quarter-

I.) Waxing Gibbous-

3.) Lunar Month- The Time from one new moon to the next A.) Length- 29.5 DAYS

Eclipse Umbra- The total Shadow surrounding the Umbra 1.) Lunar Eclipse- Occurs when the moon passes into Earth's Umbra. A.) Only occurs at the full moon phase B.) The Moon's and Earth's orbit are inclined to each other by 5 degrees so a lunar eclipse does not occur every month. (1 Per Year) 2.) Solar Eclipse- Occurs when the moon's Umbra Reaches Earth's Surface A.) Locations on the Earth's surface within the Umbra Experience a total solar eclipse. B.) Locations in the Penumbra receive a partial solar eclipse. C.) Can only occurs at the New Moon phase.