MoonsChapter 18Section 2Lecture 1

What is a satellite?• A satellite is a natural or artificial body that

revolves around large bodies like planets.• All of the planets, except for Mercury &

Venus, have natural satellites called moons.

Artificial satelliteArtificial satellite

Natural satellite Natural satellite

Our Lovely Moon• Our moon is called Luna, the Latin word for moon.• Our moon has a lower density than Earth & samples

of lunar rocks brought back by the Apollo astronauts suggests the moon is similar to the Earth’s mantle.

• The oldest lunar rocks are about 4.6 billion years old.• The moon is also covered in craters. • By counting these, we know exactly how many times

the moon has been hit .

Did Earth Have Two Moons?

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Interesting Facts• The moon changes slightly every single night. • There is no air, food, or liquid water on the

moon.• The moon’s gravity is too weak to hold an

atmosphere.• The moon reflects only 7% of the light that

falls on it.• Every full moon has a name. The most familiar

is the harvest moon, which occurs in the fall. • More than 70 spacecraft have been sent to

the moon.• 12 astronauts have walked on the surface• Check out: Google Moon

Why do we only see one side of the moon?

• Think about it: every time you look at the moon, it looks the same. Same man on the moon, same bunny rabbit, always the same.

• This is because the moon rotates at the same rate it revolves (27 days, 7 hours, 43 minutes) - so the same side always faces Earth.

• This is called synchronous rotation.• There is a part of the moon we never will

see from Earth. • There is no such thing as the dark side of

the moon because the sun shines on all sides of the moon in turn.

How was the moon formed?

2. How was the moon formed?

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The Phases of the Moon

FULL MOON

WAXING GIBBOUS FIRST QUARTERWAXING CRESCENT

NEW MOON

WANING CRESCENT

LAST QUARTER

WANING GIBBOUS

Week 1

1. New Moon -When the Moon is roughly in the same direction as the Sun, its illuminated half is facing away from the Earth, and therefore the part that faces us is all dark. When in this phase, the Sun and the Moon rise and set at about the same time.

2. Waxing Crescent - As the Moon moves around the Earth, we get to see more and more of the illuminated half, and we say the moon is waxing. At first we get a silver of it, which grows as the days go by.

Waxing = to increase in power/brightness

Week 2

3. First Quarter - A week after the New Moon, when the Moon has completed about a quarter of its turn around the Earth, we can see half of the illuminated part; that is a quarter of the Moon.

4. Waxing Gibbous - During the next week we keep on seeing more and more of the illuminated part of the Moon.

gibbous = almost full

Week 3

5. Full Moon - Two weeks after the New Moon, the Moon is now half way through it’s revolution, and now the illuminated half coincides with the one facing the earth, so that we can see a full disk. At this time the Moon rises as the Sun sets, and it sets as the Sun rises.

6. Waning Gibbous - From now on, till it becomes new again, the illuminated part of the Moon decreases, and we say that’s a waning.

Waning = to decrease in power/brightness

Week 4

7. Last Quarter - Three weeks after the new, we again see half of the illuminated part.

8. Waning Crescent - Finally, during the fourth week, the Moon is reduced to a thin silver crest.

Other Moons• Many of the planets

have moons - both large and small

• All of the gas giants have many moons

• Many of the very small moons may be captured asteroids

• 4 moons are larger than our moon: Ganymede, Titan, Callisto & Io

3. Scientists research surface of the Titan moon

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Eclipses• An eclipse occurs when the shadow of one celestial body

falls on another. • It’s all about blocking light & creating a shadow.• Eclipses don't last longer than a few hours because both

planets or moons are moving. • The amount of eclipse is also dependent on your location. • The same eclipse might be a total eclipse for someone in

Brazil, but only a partial eclipse for someone in Florida. • Why don’t we see solar and lunar eclipses every month?

– Because the moon’s orbit is titled by about 5˚– This means the moon stays out of Earth’s shadows most

of the time, and vice versa

Lunar Eclipse

• Occurs when the Earth comes between the sun and the moon.

• During a total lunar eclipse, the moons often appears to turn a deep red.

• There are 2 to 3 lunar eclipses a year• Partial lunar eclipses are a little more

common than total lunar eclipses• Lunar eclipses are totally safe to look

at.

Solar Eclipse• Occurs when the moon comes

between the sun and the earth.• The Moon casts a shadow over a

portion of the planet, leaving that area in darkness.

• If you were watching from space, you could see the shadow pass over the surface.

• You would also notice that the Moon's shadow only covers a part of the planet because the Earth is much larger than the Moon.

Solar Eclipse• There are 1-2 solar eclipses each

year. • A total solar eclipse happens when

the Moon blocks the entire Sun. • An annular or partial solar eclipse

only covers some of the Sun. • There are different eclipses because

the Moon can be closer or further away from the surface of the Earth.

• Never look directly at a solar eclipse.• Turkey Eclipse 2006

What if we had no moon?We’ll get to watch that movie

on Friday

BrainPops!

1. The Moon :click here

2. Moon Phases: click here

3. Eclipse: click here

4. Tides: click here

Brain Pops: The Moon

2. Moon Phases

3. Eclipse

4. Tides

Let’s talk about the moon Journal

• After we talk about the moon journal, you’ll be going into the computer lab to watch the 4 Brain Pops that have to do with the moon.

• THEN, you’ll have some time to start working on you Chp 18 little book that is due next week

4. And in conclusion… here’s Bill

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