Astronomy 5-9-13

2 types of models Geocentric model- a model which places the Earth at the center of the solar system. Proven wrong! Heliocentric model- Sun is at the center of the solar system. All planets revolve around the sun One that is true today!

Explain the difference between pictures 1 and 2. What is each called Explain the difference between pictures 1 and 2. What is each called? Which one do we believe today? 1. 2.

Galileo-supported heliocentric model He discovered the moons of Jupiter orbit an object other than Earth. Galileo noticed that the four visible moons of Jupiter appeared to orbit around Jupiter and therefore did not revolve around the Earth.

Inertia & Gravity Newton- 2 factors Inertia and gravity keep the planets in orbit Gravity- attracts all objects toward each other- depends on mass and distance Newton found Earth keeps pulling the moon toward it with gravity Moon keeps moving ahead of Earth because of inertia

Which is the correct choice for order and size of planets?

My Very Easy Method Just Set Up Nine Planets

Seasons Caused by Revolution of Earth around the sun. Revolution- movement of an object around another object 1 complete revolution= a year (365 ¼) Revolves in path called an orbit

Summer- July 4th Winter- Jan. 4 Aphelion -- the point on its orbit when the Earth is farthest from the sun Perihelion -- the point on its orbit when the Earth is closest to the sun

*Closer to the sun, stronger the gravitational attraction and the faster the object moves* winter summer

Earth’s elliptical orbit

Day and Night Caused by Rotation of Earth on its axis Axis- imaginary line through Earth’s center and the North and South poles Earth rotates eastward- the sun appears to move westward across the sky Night- side that does not face the sun Day- side that faces sun Takes 24hrs or 1 day!

360°÷24hours= 15°/hr Earth spins at 15 degrees per hr Rotation Takes 24 hours for Earth to rotate once How long does it take the Earth to spin once? How many degrees is a full spin? 360°÷24hours= 15°/hr Earth spins at 15 degrees per hr

Evidence of rotation Foucault Pendulum: The first good evidence of the earth's rotation was provided by a swinging pendulum. The pendulum would continue to swing in the same direction while the Earth rotated beneath it

Coriolis effect- Evidence that the Earth rotates Winds in the Northern hemisphere Are deflected to the right

Time Zones Longitude- E/W of Prime Meridian Time Zones- every 15o to the west subtract an hour, every 15o to the east add an hour

Solar eclipses A solar eclipse happens when the moon blocks our view of the sun. This happens when the Moon is exactly between the Sun and the Earth. 2 types: Partial Solar Eclipse and Total Solar Eclipse

Lunar Eclipse A lunar eclipse occurs when the Earth's shadow falls on the moon. Lunar eclipses occurs about every 6 months. Types of Lunar Eclipses Total Eclipse - When the entire moon enters the Earth's umbra (the darkest part of its shadow), this is called a total eclipse. Partial Eclipse - When only part of the moon enters the Earth's umbra, this is called a partial eclipse.

Tides Are periodic rises and falls of large bodies of water. Caused by the gravitational interaction between the Earth and the Moon. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the Earth is also being pulled toward the moon Since the earth is rotating while this is happening, two tides occur each day.

Spring tides Are strong tides They occur when the Earth, the Sun, and the Moon are in a line. Spring tides occur during the full moon and the new moon.

Neap tides Are weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.