The Moon Chapter 25.

Presentation on theme: "The Moon Chapter 25."— Presentation transcript:

The Moon Chapter 25

Total Lunar Eclipse February 20, 2008 Peak 10:26 pm

Viewing Area Next Total Lunar Eclipse: December 21, 2010
Next Total Solar Eclipse: August 1, 2008

Partial Lunar Eclipse June 26, 2010

How Long Does it Take to Get There?
a. THE FLYING TIME FROM THE EARTH TO THE MOON can be expressed as a three-week, nonstop ride in a jet airplane, traveling at 500 miles per hour. It would take approximately one school day to fly across the continental United States at the same speed. b. TRAVELING TO THE MOON BY CAR at 55 miles per hour for 12 hours a day would require one year’s worth of time to complete the trip. Of course, one would have to return which would require an identical amount of time. A student could miss two full years of school on a round trip to the moon. Any volunteers...?

Apollo 11 Crew:  This is the most famous picture taken by NASA of the three-member crew that flew in Apollo 11, the first mission where people walked on the moon. Everyone knows that Neil A. Armstrong was the first astronaut to walk on the moon, but do you know his location in the picture? The astronaut sitting on the right is Buzz Aldrin, the second person to walk on the moon. The standing astronaut is Michael Collins. He remained in the Command Module while Buzz and Neil walked. Yes, Neil is seated on the left with the biggest smile.

The Moon: An Introduction
A. The moon is a satellite ( a smaller body orbiting around a larger one) 1. Luna- Latin from moon 2. Diana, or Luna, Roman goddess of the Moon, animals, and hunting (earth’s moon).

Name the three astronauts that first landed on the moon.
Draw the shape of the moon as seen this past weekend. Neil Armstrong, Buzz Aldrin, Michael Collins

B. Physical Properties of the Moon
Size a. Diameter: 2,160 miles (3,476 kilometers) b. Compared to Earth Diameter of: Moon = ,160 = or about ¼ Earth ,000 c. Scale of Size

2. Gravity a. The Moon has 1/6 the gravity of Earth.
b. The Earth is 81 times more massive (weight) than the moon. The moon’s average density is 3.3 g/cm3 and the Earth’s average density is 5.5 g/cm3. A person standing on the moon would feel as if his or her weight had decreased by 5/6. And if that person dropped a rock, the rock would fall to the surface much more slowly than the same rock would fall to Earth.

3. Atmosphere a. The moon has a very limited atmosphere (aka: exosphere). b. On the moon, the sky always appears dark, even on the bright side.

4. Temperatures a degrees F (+127 degrees C) on the lighted side. b degrees F (-173 degrees C) on the dark side. c. These large temperature extremes or differences exist because the moon has very little atmosphere.

C. Lunar Topography Tycho Crater
Crater- circular hollows on moon’s surface -caused by impacts from meteoroids/asteroids Rays- cracks that radiated outward from craters - can reach hundreds of kilometers in length Tycho Crater

Maria- Latin for seas - Large dark areas on moon caused by volcanic activity. - Higher density of surrounding areas (mascons). - Basalts Sea of Serenity Sea of Rains

Highlands- usually found on the edges of maria
- Lower density. - Anorthosite (igneous) Apennine Mt. & Caucasus Mt.

Regolith- loose rock material (small rocks, sand, dust)
- Contains no water or organic materials (NOT soil)! - Depths of 2-20 meters. Buzz Aldrin’s footprint in Regolith

D. The Moon’s Revolution
1. Period of Revolution a. 27 1/3 days OR b. 1 month 2. The moon revolves around the Earth in an elliptical orbit, and Earth is at one foci. 3. This causes the moon’s apparent diameter to change in a cyclic manner.

The Moon month: Sidereal Month= the time the Moon takes to complete one full revolution around the Earth with respect to the background stars. However, because the Earth is constantly moving along its orbit about the Sun, the Moon must travel slightly more than 360° to get from one new moon to the next days (27 d 7 h 43 min 11.5 s) Synodic Month= the time it takes for the Moon to complete one cycle of phases. That is, the time between successive new moons days

E. Phases of the Moon 1. Caused by the orbit (revolution) of the moon and the rotation of Earth. 2. Our Earth view of the changing phases is the view of the sunlit portion and the dark portion of the moon.

3a & b. Phases of Moon as Viewed from Earth and Space.
Sun’s Rays

c. (1) Waning- the decreasing of the moon’s visible surface; from full moon to new moon.
Light on left = leaving c. (2) Waxing- the increasing of the moon’s visible surface; from new moon to full moon. Wax on right!

F. The Near and Far Sides of the Moon
1. The Near Side- the side of the moon that always faces Earth. It is nearly half highlands and half maria. 2. The Far Side- the side of the moon that never faces Earth. It is mostly highlands/craters. 3. The same side of the moon (the near side) always faces Earth because: the period of the moon’s rotation and revolution are nearly equal. The dark side is NOT always dark! Rotation = 27.3 days Revolution = 27 days 8 hours

Far Side Near Side

Picture of Mare Imbrium with the craters Plato and Cassini, the Alpine Valley, Mt. Pico and Mt. Piton

Moon Phases Animation

What is moonrise time? Sunset

What is the phase? Waxing Gibbous

What is the name of the next phase?
Waning Crescent

What is the phase? Waxing Crescent

What is the phase? Full Moon

What is the phase? Waning Crescent

What is the phase? Waxing Quarter or First Quarter

What is the name of the next phase?
New Moon

What is the phase? Waning Quarter or Last Quarter

What is the moonset time?
Midnight

What is the phase? Waning Gibbous

On a particular evening a business man decides to work extra hours at his office in London because his wife went out with her friends. After some hard work he opens the curtains of his office and looks outside (see the picture), but immediately he gets in panic. Why? The moon is a waning crescent. The waning crescent is only in the sky in the northern hemisphere from about 3 am (rises) to 3 pm (sets). This moon just rose. The business man stayed at the office VERY late!

Tides A tide is the rise and fall of ocean surface levels due to the gravitational pull from the Moon and Sun.

Mont St. Michel, France

Spring and Neap Tides Spring Tide:
A tide of large range occurring during the full and new moon phases. (moon and Sun aligned in a straight line) Neap Tide: A tide of small range occurring during quarter phases of the moon. (moon and Sun at right angles to one another) PPT

Eclipses • Although the Sun is about 400 times larger than the Moon, it is also about 400 times further away. – Both appear to be about ½ degree across. – As a result of this coincidence, the Moon can completely cover the Sun, producing a total solar eclipse. Solar Eclipse = moon covers the Sun and casts a shadow on Earth (new moon phase) Lunar Eclipse = Earth casts a shadow on the moon (full moon phase)

Frequency of Lunar/Solar Eclipses • We do not get solar eclipses at every new moon because the orbit of the Moon is tilted by about 5 degrees with respect to the ecliptic. – At most new & full moons the Moon is either above or below the Sun (plane of ecliptic). – The tilted orbit of the Moon crosses the ecliptic at two points. When the Sun approaches these points, eclipses are possible. This will happen twice a year.

Lunar Eclipses • A lunar eclipse occurs when the Moon passes into the shadow of the Earth. • The lunar eclipse is visible to everyone on the night side of the Earth. • Aristotle ( B.C.) used the apparent shape of the Earth’s shadow to show that the Earth is a sphere.

Lunar Eclipse Occur during the full moon phase
* The shadow of any body consists of two parts: – The umbra is where the Sun is completely blocked from view. – The penumbra is where the Sun is only partially blocked.

Total Lunar Eclipse February 20, 2008 Peak 10:26 pm

Viewing Area Next Total Lunar Eclipse: December 21, 2010
Next Total Solar Eclipse: August 1, 2008

Total Solar Eclipse

• Under the most favorable conditions, the diameter of the shadow cone is 269 km at the Earth’s surface. – At the equator, the shadow moves at 1730 km/hr. – Totality can last as long as 7½ minutes. • A total solar eclipse occurs about once every 18 months somewhere in the world. • At any given location, a total solar eclipse occurs once every 360 years. – The next total solar eclipse in the U.S. is on Aug

Total Solar Eclipse

Solar Corona

Total Solar Eclipse • As the Moon orbits the Earth, its apparent size varies. – Only when the Moon is closest to the Earth (perihelion) can it completely block the Sun. – If the Moon does not completely cover the Sun we get an annular eclipse.

Annular Solar Eclipse New Moon is NOT at Perihelion

Origin of the Moon Images on p.32-33

Fission Theory Early in Earth’s history a molten piece tore off and flew out into space because Earth was rotating so rapidly. Problems with theory- the energy and momentum required for this to occur was not great enough.

Co-Formation Theory The moon and Earth formed at the same time from the debris circled the Sun. Problems with theory- does not explain why the moon has less iron and other elements/rocks than the Earth.

Capture Theory The moon was a celestial body that formed farther away in the solar system. It’s orbit came too close to the Earth and Earth’s gravitation captured the moon from it’s old orbit. Problems with Theory- It is very difficult for a planet to capture a large moon. The rocks on the moon have a similar isotope composition as rocks on the Earth.

Impact Theory

Impact Theory A Mars sized asteroid struck Earth during it’s early formation. The debris from the explosion condensed into what is now the moon. Supporting evidence- The elements and compounds that are absent on the moon (oxygen, water) would have been vaporized during the collision. The moon has little heavy iron-rich matter because that material had sunk deep into the Earth before the asteroid struck.

The phases of the moon are caused by the
Earth’s revolution around the Sun Moon’s revolution around Earth Moons varying distance from Earth Sun’s varying distance from the Moon

Earth rotates on its axis, causing the Moon to appear to rise each day
Earth rotates on its axis, causing the Moon to appear to rise each day. Moonrise occurs about 52 minutes later each day because as Earth completes one rotation, the Moon also Completes one rotation on its axis. Wobbles on its axis. Is incline 23.5°. Revolves part way around Earth.

Aug 02