Our Moon and Earth System The Moon Our

  • Slides: 25
Download presentation
Our Moon and Earth System

Our Moon and Earth System

The Moon – Our Nearest Neighbor A natural satellite u One of more than

The Moon – Our Nearest Neighbor A natural satellite u One of more than 96 moons in our Solar System u The only moon of the planet Earth u

Location, Location! u u About 384, 000 km (240, 000 miles) from Earth 3,

Location, Location! u u About 384, 000 km (240, 000 miles) from Earth 3, 468 km (2, 155 miles) in diameter (about ¼ the size of Earth)

Birth of Our Moon u u u “Born” 4 -5 billion years ago Formed

Birth of Our Moon u u u “Born” 4 -5 billion years ago Formed from impact of Marssized “planetesimal” on Earth Moon’s rocks are very similar to those on the Earth

Moon’s Interior u u 3 major divisions of the Lunar interior Crust - average

Moon’s Interior u u 3 major divisions of the Lunar interior Crust - average thickness of about 70 kilometers Mantle Core - radius is between 300 and 425 kilometers

The Moon’s Surface u u u No atmosphere No liquid water Extreme temperatures •

The Moon’s Surface u u u No atmosphere No liquid water Extreme temperatures • Daytime = 130 C (265°F) • Nighttime = -190 C (-310 F) u 1/6 Earth’s gravity

Lunar Features - Highlands Rilles u u u Highlands are the lighter part of

Lunar Features - Highlands Rilles u u u Highlands are the lighter part of the moon Mountains up to 7500 m (25, 000 ft) tall Rilles (trenchlike valleys)

Lunar Features - Maria u u Originally thought to be “seas” by early astronomers

Lunar Features - Maria u u Originally thought to be “seas” by early astronomers Darkest parts of lunar landscape Filled by lava after crash of huge meteorites on lunar surface 3 -4 billion years ago Mostly basalt rock

Lunar Features - Craters u u Up to 2500 km (1, 553 miles) across

Lunar Features - Craters u u Up to 2500 km (1, 553 miles) across Most formed by meteorite impact on the Moon

Movements of the Moon u u u Revolution – Moon orbits the Earth every

Movements of the Moon u u u Revolution – Moon orbits the Earth every 271/3 days The moon rises in the east and sets in the west The moon rises and sets 50 minutes later each day Rotation – Moon turns on its axis every 27 days Same side of Moon always faces Earth

Far Side of the Moon u u First seen by Luna 3 Russian space

Far Side of the Moon u u First seen by Luna 3 Russian space probe in 1959 Surface features different from near side • • • More craters Very few maria Thicker crust

It’s Just a Phase u u Moonlight is reflected sunlight Half the moon’s surface

It’s Just a Phase u u Moonlight is reflected sunlight Half the moon’s surface is always reflecting light From Earth we see different amounts of the Moon’s lit surface The amount seen is called a “phase”

FOUR MAIN SHAPES FULL QUARTER CRESCENT GIBBOUS

FOUR MAIN SHAPES FULL QUARTER CRESCENT GIBBOUS

Tides u u u Moon affects Earth by the formation of tides Moon’s gravity

Tides u u u Moon affects Earth by the formation of tides Moon’s gravity pulls on Earth along imaginary line connecting Earth and the Moon that creates bulges of ocean water on both the near and far sides of the Earth’s rotation contributes to tide formation As Earth rotates, these bulges align with the Moon Person at shoreline on Earth’s surface would see ocean level rise every 12 hours

Spring and Neap Tides u u Sun’s gravitational effect (about ½ of the Moon’s)

Spring and Neap Tides u u Sun’s gravitational effect (about ½ of the Moon’s) not as strong as the Moon’s because further away from the Earth When Sun and Moon are aligned, see stronger tides because effects are combined These higher tides are called spring tides and they are high when Moon is nearest Earth and Earth is nearest the Sun Lower than normal tides, or neap tides, occur when the Moon is at a right angle to the Sun. Earth line

Nutation u In addition to causing tides, the moon’s orbit around Earth also causes

Nutation u In addition to causing tides, the moon’s orbit around Earth also causes the Earth to nod, or bob throughout its rotational period, called nutation

Solar Eclipse u u u Solar eclipse occurs when the Moon passes directly between

Solar Eclipse u u u Solar eclipse occurs when the Moon passes directly between the Sun and the Earth and blocks our view of the Sun When the Moon perfectly blocks out the Sun’s disk, we only see the dim, gaseous outer layers of the Sun; this is called a total solar eclipse Partial solar eclipse seen when the Moon blocks a portion of the Sun’s disk

Solar Eclipse u u The difference between a partial and total solar eclipse can

Solar Eclipse u u The difference between a partial and total solar eclipse can be explained by the fact that the Moon casts a shadow on Earth Shadow consists of two regions: inner portion called the umbra that doesn’t receive direct sunlight, and an outer portion called the penumbra that receives some sunlight

u u u People who witness eclipse from the umbra (inner portion) see a

u u u People who witness eclipse from the umbra (inner portion) see a total solar eclipse People who witness eclipse from the pnumbra (outer portion) see a partial solar ecipse Umbral shadow very small (~270 km), so total solar eclipse visible from small portion of Earth Solar Eclipse

u u u Only when the Moon intersects the Earth; s ecliptic in line

u u u Only when the Moon intersects the Earth; s ecliptic in line with the Sun and Earth does a solar eclipse occur Closest point in Moon’s orbit around Earth is called the perigee Farthest point in Moon’s orbit around the Earth is the apogee Effects of Orbits

Effects of Orbits u u When Moon is near apogee, appears smaller from Earth

Effects of Orbits u u When Moon is near apogee, appears smaller from Earth and can’t block out Sun entirely When Moon is near perigee, appears larger on Earth and can block out Sun entirely

Lunar Eclipse u u Lunar eclipse occurs when Moon passes through Earth’s shadow Can

Lunar Eclipse u u Lunar eclipse occurs when Moon passes through Earth’s shadow Can only happen during a full moon when the Moon is in the opposite direction from the Sun Earth has two parts to its shadow like the moon: umbral and penumbral When entire Moon is in the Earth’s umbral shadow, you can see a total lunar eclipse

Periodicity of Eclipses u u u Solar and lunar eclipses don’t occur every full

Periodicity of Eclipses u u u Solar and lunar eclipses don’t occur every full moon because the Moon in orbit usually passes above or below the Sun as seen from Earth Solar and lunar eclipses occur in almost equal numbers, with slightly more lunar eclipses Maximum number of combined eclipses that can occur per year is seven; this won’t happen again until 2038

Moon base of the future? u What would you need to live there?

Moon base of the future? u What would you need to live there?