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1 Describe the structure of the moon 2. Describe its surface features 3. Summarize the hypothesis of moon formation
•moon -a body that revolves around a planet and that has less mass than the planet does. •A natural satellite
•satellite a natural or artificial body that revolves around planet.
•One of more than 96 moons in our Solar System •The only moon of the planet Earth
Earth
7930 miles (12,756.3 km) diameter
23 degree axis tilt (seasons!)
Surface temps –73 to 48 C (-100 to 120F)
Thick atmosphere, mild greenhouse effect
Liquid water – lots! - at surface
2160 miles (3476 km) diameter
7 degree tilt (no seasons)
Surface temps - 107 C to –153 C (224 F to –243 F)
No atmosphere
No liquid water … Ice at poles in shadows?
Moon
Birth of the Moon: 1.began when a Mars-sized “planetesimal” collided with Earth more than 4 billion years ago. 2.The collision ejected chunks of Earth’s mantle into orbit around Earth. 3. The debris eventually clumped together to form the moon. This hypothesis explains why moon rocks share many of the chemical characteristics of Earth’s mantle.
3 major divisions of the Lunar interior
Crust - average thickness of about 70 kilometers
Mantle Core - radius is
between 300 and 425 kilometers
The side of the moon that faces Earth is called the near side, while the side of the moon that faces away from Earth is called the far side. The moon’s crust is thicker one side than the other. The crust on the near side is about 60 km thick. The crust on the far side is up to 100 km thick. The difference in thickness was caused by the pull of Earth’s gravity during the formation of the moon.
Beneath the crust is the moon’s mantle. The mantle is thought to be made of rock that is rich in silica, magnesium, and iron. Scientists think that the moon has a small iron core that has a radius of less than 700 km. Studies of the core have shown that the moon’s rotation is not uniform and that the core is neither completely solid nor completely liquid.
mare -a large, dark area of basalt on the moon Any feature of the moon is referred to as lunar. The light patches seen on the moon’s surface are called anorthosites. The darker areas are called maria. Maria are plains of dark, solidified lava which form more than 3 billion years ago when lava slowly filled basins that were created by massive asteroids
crater -a bowl-shaped depression that forms on the surface of an object when a falling body strikes the object’s surface or when an explosion occurs The surface of the moon is covered with craters, rilles, and ridges. Most of the craters formed when debris struck the moon about 4 billion years ago. Rilles -are long, deep channels that run through the maria. Rilles are thought to be leftover lava channels from the formation of the maria. The moon’s surface also has several ridges, which are long, narrow elevations of rock that rise out of the surface and criss-cross the maria.
The moon’s surface is very susceptible to meteorite hits because the moon has no atmosphere for protection. Over billions of years, these meteorites crushed much of the rock on the moon’s surface into a layer of dust and small fragments called regolith. The depth of regolith on the moon varies from 1 m to 6 m.
Lunar rocks are igneous, and most rocks near the surface are composed mainly of oxygen and silicon. Rocks from the lunar highlands are light-colored, coarse-grained anorthosites that contain calcium and aluminum. Rocks from the maria are fine-grained basalts and contain titanium, magnesium, and iron. Breccia is found in both maria and the highlands. Lunar breccia formed when meteorites struck the moon.
• 1960-1977 seismometers were tracking moonquakes, average of 5.5 on the Richter scale.
• There are 4 types of moonquakes: 1.Deep moonquakes (likely caused by tidal stresses caused by the gravitational tug of war between the Earth, Moon and Sun.) 2.Meteorite induced tremors 3. Thermal quakes(freezing crust expands as it returns into sunlight after two weeks of lunar night time) 4. Shallow quakes (due to landslides of rock down steep crater rims) • 1-3 are generally mild and harmless • Last long time some for 10minutes, earthquakes rarely surpass 2
minutes usually between 10-30seconds
• No current plate tectonics • Moon has cooled to point of inactivity (for about 3
billion years now) • So no current volcanoes • current moonquakes not due to plate tectonics
1.Describe shape of the moon’s orbit using apogee and perigee. 2. Describe the types of eclipses and what is happening to the Moon and Earth during them
Earth and the moon revolve around each other. Together they form a single system that orbits the sun.
The balance point of the Earth-moon system is located within the Earth’s interior, because Earth’s mass is greater than the moon’s mass.
This balance point is called the barycenter. The barycenter follows a smooth orbit around the sun.
Apogee- in the orbit of a satellite, the point at which the satellite is farthest from Earth Perigee- in the orbit of a satellite, the point at which the satellite is closest to Earth When the moon is farthest from Earth, the moon is at apogee. When the moon is closest to Earth, the moon is at perigee. The orbit of the moon around Earth forms an ellipse, the distance between Earth and the moon varies over a month’s time. o Moon rotates once on its axis every 27.3 days o One lunar day equals 29.5 Earth days o due to moon and Earth both revolving around the sun in
addition to the moon going around the Earth.
The moon appears to rise and set at Earth’s horizon because of Earth’s rotation on its axis. The moon rises and sets 50 minutes later each night. This happens because of both Earth’s rotation and the moon’s revolution. While Earth completes one rotation each day, the moon also moves in its orbit around Earth. It takes 1/29 of Earth’s rotation, or about 50 minutes, for the horizon to catch up to the moon.
The moon’s revolution around Earth and its rotation on its axis take the same amount of time. Because the rotation and revolution take the same amount of time, observers on Earth always see the same side of the moon.
• The part of the moon illuminated by sunlight changes as the moon orbits Earth.
• The Sun always illuminates half of the moon and half of the Earth.
• The near side of the moon can be completely illuminated, partially illuminated or completely darkened depending on where it is in its orbit
• This gives the phases of the moon
eclipse -an event in which the shadow of one celestial body falls on another Bodies orbiting the sun, including Earth and its moon, cast long shadows into space. An eclipse occurs when one body passes through the shadow of another. Shadows cast by Earth and the moon have two parts: the inner, cone-shaped part of the shadow called the umbra and the outer part of the shadow called the penumbra.
solar eclipse- the passing of the moon between Earth and the sun; during a solar eclipse, the shadow of the moon falls on Earth. During a total solar eclipse, the sun’s light is completely blocked by the moon. The umbra falls on the area of Earth that lies directly in line with the moon and the sun. Outside the umbra, but within the penumbra, people see a partial solar eclipse. The penumbra falls on the area that immediately surrounds the umbra.
During a total solar eclipse, the sunlight that is not eclipsed by the moon shows the normally invisible outer layers of the sun’s atmosphere. This causes what is known as the diamond-ring effect, because the sunlight often glistens like the diamond on a ring. If the moon is at or near apogee during a solar eclipse, the moon’s umbra does not reach Earth. This causes an “annual eclipse” in which a thin ring of sunlight is visible around the outer edge of the moon. The brightness of this ring prevents observers from seeing the outer layers of the sun’s atmosphere (corona).
lunar eclipse - the passing of the moon through Earth’s shadow at full moon A lunar eclipse occurs when Earth is positioned between the moon and the sun and when Earth’s shadow crosses the lighted half of the moon. When only part of the moon passes into Earth’s umbra, a partial lunar eclipse occurs. When the entire moon passes through Earth’s penumbra, a penumbral eclipse occurs.
1. Identify and summarize the pattern of moon phases 2. Understand and explain why the moon goes through phases
phase - the change in the illuminated area of one celestial body as seen from another, celestial body phases of the moon are caused by the changing positions of Earth, the sun, and the moon As the moon revolves around Earth, different amounts of the near side of the moon, which faces Earth, are lighted. Therefore, the apparent shape of the visible part of the moon varies. The varying shapes are called phases.
• The moon passes through four major shapes during cycle that repeats itself every 29.5 days.
• The phases always follow one another in the same order.
• New Moon
• First Quarter
• Third Quarter
• Full Moon
• The lighted side of the moon faces away form the Earth.
• This means the Sun, Earth, Moon are almost in a straight line
• The moon that we see looks dark
• The right half of the Moon appears lighted and the left side of the Moon appears dark.
• During the time between the New Moon and the First Quarter Moon, the part of the Moon that appears lighted gets larger and larger every day, and will continue to grow until the Full Moon.
• The left half of the Moon appears lighted, and the right side of the Moon appears dark.
• During the time between the Full Moon and the Last Quarter Moon, the part of the Moon that appears lighted gets smaller and smaller every day. It will continue to shrink until the New Moon, when the cycle starts all over again.
• The lighted side of the Moon faces the Earth.
• This means that the Earth, Sun, and Moon are nearly in a straight line, with the Earth in the middle.
• The Moon that we see is very bright from the sunlight reflecting off it.
• Between the four main phases are crescent and gibbous shaped moons
• These phases include
• Waxing crescent
• Waxing gibbous
• Waning gibbous
• Waning crescent
• Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight.
• Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight.
Waxing- When the size of the lighted part of the moon is increasing When a sliver of the moon’s near side is illuminated, the moon enters its waxing-crescent phase. When a waxing moon becomes a semicircle, the moon enters its first-quarter phase. When the lighted part of the moon’s near side is larger than a semicircle, the moon is in its waxing-gibbous phase. At full moon, the entire near side of the moon is illuminated by the light of the sun.
Waning - When the lighted part of the near side of the moon appears to decrease in size When the moon is waning, but is still larger than a semicircle, the moon is in the waning-gibbous phase. When the moon is waning, and it is a semicircle, the moon enters the last-quarter phase. When only a sliver of the near side is visible, the moon enter the waning-crescent phase. After this phase, the moon becomes a new moon, in which no lighted area of the moon is visible from Earth.
New moon Waxing crescent First quarter Waxing gibbous Full moon Waning gibbous Third quarter Waning crescent Starts at new moon again
e moon revolves around Earth in 27.3 days, however, the period from one new moon to the next one is 29.5 days.
moon revolves around Earth in 27.3 days, however, the period from one new moon to the next one is 29.5 days. This difference of 2.2 days is due to the orbiting of the Earth-moon system around the sun. In the 27.3 days in which the moon orbits Earth, the two bodies move slightly farther along their orbit around the sun. So, the moon must go a little farther to be directly between Earth and the sun. About 2.2 days are needed for the moon to travel this extra distance.
Bulges in Earth’s oceans, called tidal bulges, form because the moon’s gravitational pull on Earth decreases with distance from the moon. As a result, the ocean on Earth’s near side is pulled toward the moon with the greatest force. The solid Earth experiences a lesser force. These differences cause Earth’s tidal bulges. Because Earth rotates, tides occur in a regular rhythm at any given point on Earth’s surface each day.
