astronomy, part 2

1 Astronomy Part 2 Notes

Astronomy, PART 2

Vocabulary

Astronomy -

I. Earth’s Place in the Universe

A. Universe - Our Milky Way Galaxy is one of of galaxies in an expanding universe.

B. - Our Sun/solar system is one of an estimated stars making up this spiral galaxy

C. Our Solar System - Earth is a small, dense one of that orbit the sun.

D. The Gas GIANTS or

E. Asteroids, Comets, and Meteoroids

Asteroids - Small, rocky bodies that orbit the Sun. The is located between and

. Comets - Body of methane, ammonia ,and

Aphelion Asteroid Astronomical Unit Comet Constellation Crater

Eccentricity Eclipse Equinox Geocentric model Gravitation Heliocentric model

Inertia Jovian Perihelion Revolution Rotation Lunar Penumbra

Seasons Solstice Tropic of Cancer Tropic of Capricorn Terrestrial Tides

Umbra


Orbit the sun in long Made of 3 parts: __________________made of rock, metals, and ice __________________cloud of gas and dust surrounding the nucleus __________________gas and dust streaming from the head and always points AWAY from the sun

_____________________- small bits of rock or metal that move throughout the solar system _________________ - once it enters Earth’s atmosphere

most burn up in the atmosphere and produce a long streak, which is known as a

occasionally large numbers enter the atmosphere in a short period of time, creating a ______________ - if the meteor doesn’t burn up completely in the atmosphere and strikes Earth

II. Measuring Distance A. Light Year ______________________________________________________________ ____________________________________________________ The speed of light is 186,000 mi/sec. a. We see all night stars as they WERE when the light .

When we look at distant stars and galaxies, we look back in . B . Astronomical Unit 1 AU = The distance between !

III. Models of the Universe A. Geocentric Model

A. About 2000 years ago, the Greek astronomer, Claudius

developed a detailed model of the universe based on the idea of

.

2. In this model of the universe, was at the center, and all heavenly bodies

in .

3. Ptolemy’s geocentric model, as illustrated on the next page, can be summarized as follows:


a. Earth is located in the and does not move.

b. The are located on a transparent sphere that rotates once each day

from to around Earth.

c. The the and each are carried by separate

spheres of different sizes.

d. Each planet is located on an “ “ that also rotates.

This explained -

e. This model was accepted for almost 1400 years because it explained celestial observations made

from Earth and……… it seemed obvious.

B. Heliocentric Model

Copernicus’ heliocentric model can be summarized as follows:

1. The is located in the of the system and does NOT move.

2. The are located on a stationary/unmoving transparent

sphere. The sphere is a great distance from the sun.

3. The including move in

around the sun.

4. The moves in a circle around .

5. rotates on its axis from west toward east each day. HOWEVER………

Copernicus’ heliocentric model does NOT explain the apparent cyclic variations in the size of the Sun, and the cyclic

variation in orbital speeds of the planets. This is because in the heliocentric model, .


C. Johannes Kepler 1. In 1609, published a book which included his first 2 “Laws of Planetary Motion”. These laws explain why

the apparent size of the sun changed, and why the speed of a planet changes as it orbits the Sun.

a. Kepler’s 1st law: The orbit of each planet is an with the sun at one focus and an imaginary point in

space at the other focus.

An ellipse looks like an oval, or squashed circle. The longest line drawn from one end of the ellipse (through the center) to the other side is called the . For a circle, the two foci lie on top of each other.


= degree of the “out-of-roundness” of an ellipse.

Eccentricity can be calculated as e = Distance between the foci

Length of the Major Axis

The eccentricity of a circular orbit is , and can range from zero to less than

for an ellipse.

Relationship: As the distance between the focal points , the shape of the ellipse becomes more oval (Line = 1)

b. Kepler’s 2nd law: describes the fact that

Area A = Area B

1. __________________ = Point in orbit when object is nearest the sun.

2. __________________ = Point in orbit furthest from sun

c. Kepler’s 3rd law: The further a planet is from the sun, the it’s period of revolution!

1. Farther planets have orbital paths

2. Farther planets have orbital paths

D. Sir Isaac Newton

1. Newton’s Laws of Gravity a. 1st Law: and will pull all other objects with a certain gravitational

force.

b. 2nd Law: The mass of an object will determine the amount of gravitational force that object possesses. The the

mass, the the gravitational force.

c. 3rd Law: The gravitational force between 2 objects changes as the distance between them change. As the distance

gravitational pull will .


The Inverse Square Law: If you half the distance between two objects, you quadruple the gravitational force between them.

2. Gravity and Inertia

a. Newton’s Law of Inertia states that a body in motion will continue in motion unless acted on

by an .

INERTIA + GRAVITY =

IV. Rotation -

A. Earth’s Direction of Rotation:

to

Angular Rate of Rotation:

THINK – one complete rotation

degrees

hours

Rate = 360°/24 hours =

B. Effects of Earth’s Rotation

1. _____________ and _________________

2. Apparent daily motion of

a. Earth rotates from to

b. Sun “appears” to move in an arc from to

Earth is NOT a perfect sphere. It is an – slightly wider across the

equator (due to its rotational spin)


Earth‘s axis is not stable. It moves/wobbles (like a top). This is known as . It’s

very slow - 26,000 years to complete one cycle.

Within the precession are additional motions known as . These are

smaller motions back and forth as the precession occurs.

IV. Revolution

The of one celestial body around another object.

A. Earth’s Angular Rate of Revolution

1. degrees (Think CIRCLE)

2. days

3. Rate = 360°/365 days ~ =

B. Effects of Earth’s Revolution

1. Nighttime constellations change in a yearly cycle.

2. – groups of stars that form patterns of imaginary things such as animals, legendary heroes, and mythological gods.

3. ____________________ – A yearly cycle

5. Seasons of the Year

A. Causes:

1. _____________________________- Earth revolves around the sun

2. _____________________________ - Earth is tilted/inclined on axis 23

1/2o

3. _____________________________ - Earth’s axis always points in the

same direction.


B. Earth’s axis is tilted _________________ relative to the plane of it’s orbit. (Draw and label your diagram according to the diagram at the right. Be sure to name the equator, the Tropic of Cancer and Capricorn and note where we live.)

C. The apparent path of the sun changes with the and with .

D. Length of Daylight (duration of daylight) – changes with and with .

E. Factors Affecting Insolation

1. Shape of the Earth ( )

2. As latitude increases, the angle of insolation and the intensity of insolation

3. Season of the Year

a. As Earth travels along its orbital path around the sun, the angle of insolation at a given latitude changes with the seasons. This depends on

how far a given latitude is from the direct rays of the sun. The direct rays migrate between the and the


4. Time of Day

a. The angle of insolation changes in the course of one day. Maximum intensity occurs at .

b. Looking South

A. The shadow of a vertical pole indicates how the angle of insolation changes during the day. The higher/greater the insolation, the

the shadow, and the the intensity of insolation.


VI. The Moon

A. The Moon is a .

1. - is Latin for Moon.

2. - Roman Goddess of the Moon.

B. Physical Properties of the Moon

1) Size

i. Diameter = miles.

ii. Compared to the Earth:

1. Diameter =Moon

Earth 8000_____

2. Gravity:

a. the gravity of Earth.

b. This is because the Moon has

2) Atmosphere

a. The Moon has .

b. Gravity is too weak so

c. Without an atmosphere radiation from the sun is

d. You would get a sunburn in seconds.

e. Frozen water may exist at the Moon’s but no liquid water would exist.

3) Temperatures

a. It is on the lighted side of the Moon.

b. It is on the far side of the Moon.


c. These large temperature extremes exist because

4) Lunar Topography

a. - bowl-shaped depressions formed primarily as a result of

impact of meteors.

i. Most cratering occurred during a heavy bombardment period which gave

Earth it’s early CO2 atmosphere – 4 billion years ago.

ii. There are many more craters on the Moon than on the Earth because

.

b. - smooth glassy regions, which are generally craters

filled in by lava.

c. The surrounding rough regions are called

5) The Moon’s Revolution

a. Period of Revolution = or

b. The Moon travels around the Earth in an orbit

with the Earth at one

c. This causes the Moon’s apparent to

change in a manner.


6) Phases of the Moon

a. The phases of the Moon are caused by the moon’s .

b. This is an Earth view of the changing illuminated part of the Moon’s surface that faces the Earth.

c. - the decrease in light (on the left); from full moon to new moon.

d. - the increasing of the Moon’s visible illuminated surface (on the right); from new moon to full

moon.

Phases

Phase #1

_ - when the Moon is roughly in the same direction as the sun, it’s illuminated half is facing away from the

Earth and therefore the part that faces us is all dark.

Phase # 2

Phase # 3

____________________________

Phase # 4

___________________________

Phase # 5

___________________________

Phase # 6

___________________________

Phase # 7

___________________________

Phase # 8

___________________________


7) Moon Rotation?

a. The same side of the Moon always faces the Earth.

b. Does this mean that the Moon doesn’t rotate?

c. YES IT DOES!!!

.

8) Lunar Eclipse

a. An eclipse of the Moon can only take place at

and only if the Moon passes through some portion of the Earth's shadow. The shadow is actually composed of two cone-shaped

components, one inside the other. The outer or shadow is a zone where some portion of

the Sun's rays are blocked. In contrast, the inner or shadow is a region devoid of all

direct sunlight.

9) Solar Eclipse

a. A Solar eclipse occurs when the passes directly between the Earth and the Sun.

b. are the only time solar eclipses occur.


10) Tides

a. Tides are the alternate and of the sea

b. This is caused by the gravitational pull on the surface waters.

c. The rising of tides is affected by the position and

d. The period from high tide and high tide is normally about hours and minutes.

e. Tides are a change.

astronomy, part 2

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