Astronomy

@ SAG - Marek - '24 (P3)

Two pieces of evidence that the Earth rotates

Coriolis Effect and Focault’’s Pendulum

The Earth rotates

West to East, 15° per hour, in 24 hours

The Earth revolves

counterclockwise, takes 1 year, 1° per day

Stars on Polaris make

counterclockwise circles, Polaris stays still

Revolution

orbiting around another object

Rotation

spinning around an axis

Revolution causes

different constellation to be visible at different times of the year

Revolution creates

seasons

The altitude of Polaris equals

the latitude of the observer

Celestial objects (Sun, Moon, Planets) rise in the

East and set in the West due to Earth’s rotation

The moon has phases because

it revolves around the Earth, in one month or 29.5 days (½ the Moon is always lit)

We always see the same side of the Moon

it rotates and revolves at the same rate (27.3 days)

A new moon occurs when

the Moon is between the Earth and the Sun SME (all dark from Earth)

A full moon occurs when

the Earth is between the Sun and the Moon SEM (all bright from Earth)

Tides are caused by the

Moon's gravitational pull because it is close to Earth (also the Sun’s but far away)

Earth is a satellite of the

Sun

The Moon is a satellite of

Earth

Satellite

any object in space moving in orbit around another object

Why do the distance between the Sun and Earth change?

Because Earth’s orbit is elliptical (oval-shaped)

The apparent shape of the Moon depends on the changing positions of

the Sun, Earth and Moon

How long does it take the Moon to revolve around the Earth?

1 Month

Which device when placed on the Moon would provide evidence of Moon rotation?

Foucault Pendulum

During a New or Full Moon, when the Earth, Moon and Sun are in a line a

spring time occurs (most extreme)

During the 1st and 3rd Quarter, when the Moon and Sun are working against each other we get

neap tides (less extreme)

Tides are

the rising and falling of the ocean

What is the pattern of tides?

Cyclic and predictable

A solar eclipse happens when

the Moon is between the Earth and the Sun and it blocks out the Sun (NEW MOON PHASE ALWAYS)

A lunar eclipse happens when

the Earth is between the Sun and the Moon and the shadow hits the Moon (FULL MOON PHASE ALWAYS)

Eclipses don’t happen every month because

the Moon’s orbit is tilted about 5 degrees

Inner four planets are

• rocky (Terrestrial)

• more dense

• smaller diameters

• faster revolutions

Terrestrial Planets

• Mercury

• Venus

• Earth

• Mars

Outer four planets are

• Gas giants (Jovian)

• Less dense

• Larger diameters

• Slower revolutions

Jovian Planets

• Jupiter

• Saturn

• Uranus

• Neptune

Asteroid Belt is located

between Mars and Jupiter

Meteor

a streak of light in the sky that occurs when a meteoroid enters Earth’s atmosphere “shooting star”

Heliocentric Model

Sun centered, planet revolve in elliptical orbits, Sun at one focus

Geocentric Model

Earth centered, wrong model, planets and Sun revolve around Earth

The Earth’s orbit is

extremely round, almost perfect, but it is slightly elliptical

Eccentricity is a measure of

how oval or elliptical the orbit is (highest = 1, line) (lowest = 0, perfect circle)

The two factors affecting the force of gravity on an object are

mass and distance (closer = more)

As a planet gets closer to the Sun or a star

the faster it orbits (further = slower)

When an object is close it looks

bigger (has a large apparent diameter) (farther = slower)

The sun is a regular star, produces energy converting

Hydrogen into Helium by Nuclear Fusion

Gravity

an invisible force of attraction

Age of universe is approximately

13.7 billion years old

The solar system is how many years old?

4.6 billion years old

Perihelion

closest to the Sun

Aphelion

farthest from the Sun

What are the main classifications of stars?

1. Main Sequence

2. Supergiant

3. Giant

4. White Dwarf

What two characteristics are used to classify stars?

Temperature and Luminosity

What type of star is our Sun classified as?

Main Sequence

How do stars generate their energy?

Nuclear fusion

What do Polaris and the Sun have in common?

Same temperature and color

Two pieces of evidence of the Big Bang Theory and the universe is expanding

cosmic background radiation and the red shift caused by the Doppler Effect

Your universal address from smallest to largest

1. Earth

2. Solar System

3. Milky Way

4. Universe

Sunspots

dark and cool spots on the Sun

What happens when sunspots occur?

Causes sun flats

Speed of light

10 Trillion KM/YR

Light Year

the amount light can travel in one year

What is the name of our galaxy?

The Milky Way

What type of galaxy do we live in?

Spiral Galaxy

Galaxy

collection of billions of stars, planets and various amounts of gas and dust held together by gravity

Red Shift

objects moving away cause by explosion of space

Blue Shift

objects moving towards another object

Spectral Lines

separation of different colors based on wavelength