A look at our nearest neighbor in Space!
The
Moon--Luna
Formation of the Earth and Moon
How did the Moon Form?
What is the Moon?
• A natural satellite – an
naturally occurring celestial body that orbits a planet.
• One of more than 96
moons in our Solar System • The only moon of the planet
Location, location, location!
• About 384,000 km
(240,000 miles) from Earth
The Moon’s Surface
• No atmosphere • No liquid water • Extreme
temperatures
– Daytime = 130C (265°F)
– Nighttime = -190C (-310 F)
Lunar Features - Highlands
• Mountains up to 7500 m (25,000 ft) tall
• Rilles (trenchlike valleys)
Lunar Features - Craters
• Up to 2500 km (1,553 miles) across
Lunar Features - Maria
• 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
Maria Craters
Phases of the Moon
• The phases, or
cyclical changes in appearance of the
Phases of the Moon
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
Moon Phases
• The moon goes around the earth, on average, in 27 days 7 hours 43 minutes.
• We experience a new full moon about every 29 days.
Lunar phase simulator link http://astro.unl.edu/
A Day on the Earth…
• The time it takes for the Earth to rotate counterclockwise completely around its
A Year on Earth
A year is the amount of time it takes Earth to make one revolution around the sun.
Scientists have no reason to believe that the amount of time to do this has changed.
See the animation:
INTERESTING THOUGHTS
• The Earth’s rotation has slowed down since its formation.
• A day probably lasted only about 6 hours when the Earth formed.
• The year has not changed.
Movements of the Moon
• 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
• Rotation – Moon turns on its axis every 27 days, which virtually equals its revolution.
• The same side of the Moon always faces Earth because one rotation equals one revolution.
• Moon's revolution = rotation video clip
https://www.youtube.com/watch?v=OZIB_leg75
Far Side of the Moon
• First seen by Luna 3 Russian space
probe in 1959
• Surface features different from near side
Phases of the Moon
Phases of the Moon in order as
seen from Earth:
• New moon
• Waxing Crescent moon • First Quarter moon
• Waxing Gibbous moon • Full moon
• Waning Gibbous moon • Third Quarter moon • Waning Crescent moon • New moon
Definitions:
Waxing – the moon phase is getting bigger. Waning – the moon phase is getting smaller. Waxing Gibbous – the moon phase between 1st quarter and full moon—the moon is getting
larger.
Waning Gibbous – the moon phase after full moon and before 3rd quarter—it is getting
smaller.
FULL
QUARTER
CRESCENT
GIBBOUS
Earth
Moon
Moon Plane of earth’s orbit
Lunar Eclipses
• Moon moves into
Earth’s shadow – this shadow darkens the Moon
– Umbra
– Penumbra
• About 2-3 per year • Last up to 4 hours
Solar Eclipses
• 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
The Tides
• Tides caused by pull of Moon’s gravity on Earth • High tide –
– Side facing Moon and side away from Moon – Every 12 hours, 25 ½ minutes
• Low tide –
Tides
Earth Tide
The surface of the Earth actually deforms about 20 cm (8 inches) by the
High and Low Tide
• High and low tides are caused by the Earth
rotating and the relationship between areas on Earth and the moon.
• Areas that face toward and away from the moon experience high tide.
How Often and How Many?
• Most coastal areas on Earth experience two high tides and two low tides per
day.
Lag-time
• The moon travels about 1/30 of the way around the Earth each day.
• Since the moon is revolving around the Earth, the Earth has to rotate a bit more each day to “catch up” with the moon.
• This means that the moon rises and sets a little later each day.
Spring Tides
• During full and new moon phases, the
Earth, sun, and moon are in a line
• The gravity from the sun adds to the
gravity from the moon.
• The result is higher
than normal high tides and lower than
Neap Tides
• During first quarter and last quarter moon
phases, the Earth, sun, and moon are at a 90 degree angle to one another.
• The gravity of the sun partially subtracts from the gravity of the moon. • The result is lower than
Tides are slowing the Earth
• When high tides hit land, they act like a giant “brake”. This is called “tidal
friction”.
• The rotation of the Earth is slowing down
Exploring the
Moon
• 1950s to 1960s - probes
• Neil Armstrong
First man on the Moon – July 20, 1969
• Six Apollo missions (1969-1972)
– 382 kg (842 lbs) rocks
Moon base of the future?
Name this phase!
Full Moon
Name these
features.
Name
these
features.
Craters
Does this image show us the near
side or far side of the moon?
Far Side
Name this phase!
Name this phase!
Does this image show the near side or the far side of the moon?
Name this phase!
Name this
phase!
From what direction does the moon rise?
Name this phase!
Name this phase!
What might be happening in this image?
Name this phase!
Look closely!
Name this phase!
Name this phase!
Does the moon rise or set in the west?
Name this phase!
Name this
phase!
Name this phase!
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