Notes 12-3 The Moon
Jan 02, 2016
Location, location, location!
• About 384,000 km (240,000 miles) from Earth
• 3,476 km (2,155 miles) in diameter (about ¼ the size of Earth)
The Moon’s Size• The moon is 3,476 km in diameter, a little
less than the distance across the United States.
Birth of the Moon• First Stage • Moon originally was once
part of the Earth.• Scientists believe a very
large body hit the Earth early in its development, throwing a huge amount of debris into orbit.
• Debris eventually was influence by Earth’s gravity and formed the moon we have today.
Second Stage • After forming a sphere, the surface of the moon was covered by molten rock. • Eventually, this mix of rock separated.
Third Stage •The outer surface of the moon cooled, forming a crust. •Craters started to form from the constant bombardment by meteoroids.• Meteoroids decreased• Moon cooled completely• Moon changed little in 3 billion years
The Moon’s Surface
• No atmosphere• No liquid water• Extreme
temperatures– Daytime = 130C
(265°F)
– Nighttime = -190C (-310 F)
• 1/6 Earth’s gravity
Craters• Bowl shaped depressions• Up to 2500 km (1,553 miles) across• Most formed by meteorite impact on the Moon• Some formed by volcanic action inside the Moon
Maria
• Originally thought to be “seas” by early astronomers
• Darkest parts of moon
• Hardened rock formed from huge lava flows 3-4 billion years ago
Movements of the Moon
• Orbit is an ellipse, not circular
• Revolution – Moon orbits the Earth every 27 1/3 days
• Same side of Moon always faces Earth
Far Side of the Moon
• 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
• 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”
Waxing and Waning
• New moon
• Waxing Crescent moon
• First Quarter moon
• Waxing Gibbous moon
• Full moon
• Waning Gibbous moon
• Third Quarter moon
• Waning Crescent moon
• New moon
earth
moon orbit`searth
last (third)quarter
gibbous moon
full moon
gibbous moon
first quarter
crescent
new moon
crescent
waning Moon
waxing Moon
SUN
Lunar Eclipses
• Moon moves into Earth’s shadow – this shadow darkens the Moon
• About 2-3 per year
• Last up to 4 hours
• Only during full moon
Solar Eclipses• New Moon moves
between Earth and Sun
• Moon casts a shadow on part of the Earth
• Total eclipses rare – only once every 360 years from one location!
Solar Eclipse• A solar eclipse occurs when the moon passes
directly between Earth and the sun, blocking sunlight from Earth.
Exploring the Moon
• 1950s to 1960s - probes
• Neil Armstrong First man on the Moon – July 20, 1969
• Six Apollo missions (1969-1972)
• 12 Americans have walked on the moon
• Possibly send people to moon again in 2018
Extra Credit for Astronomy Test:
• Go to the website nasa.gov
• Find a topic that you are interested in and print out the information. Write a ½ page summary of the information that you find, and ½ page of why you find this topic interesting and what other questions do you have regarding the topic.
• 5 points
• Due Wednesday