List 3 facts you know about the moon

Chapter 28

Scientists use light from distant objectsRadiation = light (x-rays, gamma rays, UV,

IR, radio waves, and microwaves)Electromagnetic spectrum includes all

forms of light. We see only a small portion of this light

Visible light has a frequency between 4.3 x 1014 to 7.5 x 1014 Hz

• Electromagnetic radiation consists of waves of electrical and magnetic disturbances. • Electromagnetic radiation travels at the same speed and is classified by:

– Wavelengths—the distance between peaks on a wave.

– Frequency—the number of waves or oscillations occurring per second.

Collects light from distant objects Brings light to a focus better than the

eye Attach different detectors to observe

what the eye can’t see Used to take pictures of distant objects

Reaching for the Moon

• Plans for a crewed lunar expedition began in the late 1950s. – In 1957 the Soviet Union launched the first satellite, Sputnik

I.

– In 1961, Soviet cosmonaut Yuri A. Gagarin became the first human in space.

– On May 5, 1961, Alan B. Shepard Jr. became the first American in space

– Project Mercury was followed by Project Gemini.

– On July 20, 1969, the Apollo program landed Neil Armstrong and Buzz Aldrin on the Moon, during Apollo 11.

Reaching for the MoonLunar Properties

– Earth’s moon is one of the largest moons in the solar system.

– The Moon is relatively farther from Earth than most moons are from the planets they orbit.

– Earth’s moon is a solid, rocky body, in contrast to the icy composition of the moons of the outer planets.

– Earth’s moon is the only large moon among the inner planets.

Reaching for the MoonThe Lunar Surface

– The albedo of the Moon, the amount of sunlight that its surface reflects, about 7% (Earth’s average 31%).

– Because the Moon has no atmosphere, surface temperatures can range from 400 K (127°C) in sunlight to 100 K (–173°C) where it is dark.

– There is no erosion on the Moon—except for wear caused by recent impacts—because it has no atmosphere or flowing water.

– Craters on the Moon are preserved until one impact covers another.

Composition• The Moon is made up of minerals similar to those of Earth—

mostly silicates.

History of the Moon• Radiometric dating of lunar rocks from the highlands

indicates an age between 3.8 and 4.6 billion years. Tectonics on the Moon?

– The Moon, like Earth, has a layered structure, which consists of the crust, the upper mantle, the lower mantle, and the core.

– The Moon experiences moonquakes approximately once a year but scientists believe the Moon is not tectonically active.

– The Moon has no active volcanoes and no significant magnetic field.

History of the MoonFormation Theories

– The capture theory proposes that as the solar system was forming, a large object ventured too near to the forming Earth, became trapped in its gravitational pull, and formed into what is now the Moon.

– The simultaneous formation theory states that the Moon and Earth formed at the same time and in the same general area, and thus the materials from which they formed were essentially the same.

– The impact theory is the most commonly accepted theory of how the Moon formed. – This theory proposes that the Moon formed as the

result of a gigantic collision between Earth and a Mars-sized object about 4.5 billion years ago, when the solar system was forming.

1. Why do scientists believe that tectonic activity is not occurring on the Moon?

2. What is the most accepted theory of how the Moon formed, and what are the problems with the other theories?

The Sun-Earth-Moon System

• The relationships between the Sun, Moon, and Earth are important to us in many ways. – The Sun provides light and warmth, and it is the source of

most of the energy that fuels our society.

– The Moon raises tides in our oceans and illuminates our sky with its monthly cycle of phases.

– Every society from ancient times to the present has based its calendar and its timekeeping system on the apparent motions of the Sun and Moon.

Any object that orbits another object is called a satellite.

The moon rotates once every 27.3 days around the Earth. We never see the other side of the moon.

Gravity on the moon is 1/6 that of Earth.

Apogee – point the moon is farthest away

Perigee – point moon is at closest Earth is at apogee in summer and perigee in

winter. Eclipse – one planetary body passes in

front of another creating a shadow. Umbra – darkest part of the shadow Penumbra - light is partially blocked

Lunar eclipses don’t occur every month.

Moon is at a 5° tilt from Earth’s orbit Phases – varying shapes of the moon’s

reflected light New moon – moon is unlit from sun Waxing – increasing in light

Waxing crescent Waxing gibbous

First Quarter – half full Full moon – the whole moon is visible Waning – decreasing in light

Waning crescent Waning gibbous

Last quarter – moon is half full Earthshine – sunlight reflected off the

surface of the moon Know the phases on page 763

Earth Rise: View of Earth rising over Moon's horizon taken from Apollo 11 spacecraft. NASA picture

Earth’s axis – imaginary line going through center on which the Earth rotates.

What causes day and night and the seasons? Rotation and revolution

Earth rotates at 1600km/hr Takes 24 hours to rotate once Rotates counterclockwise (West to East) Length of day and night change due to

tilt Earth is tilted at 23 ½° Toward Sun = long days, short nights Away from Sun = short days, long nights

Year on Earth = 365.25 days Once every 4 years we add extra day

called leap day 4 seasons – Winter, Spring, Summer &

Autumn 5 other planets have seasons

Mars, Saturn, Uranus, Neptune, Pluto All are tilted on their axis

Begins on December 21 or 22 Winter solstice

Solstice means “Sun stop”

South pole is tilted a full 23 ½° toward Sun

Shortest daylight hours in Northern Hemisphere

Sun’s rays are at 90° at the Tropic of Capricorn

Begins on March 20 or 21 Vernal Equinox

Equinox means “equal night”

Neither pole is tilted toward the Sun Day and night are equal lengths

Begins on June 21 or 22 Summer solstice

North pole is tilted a full 23 ½° toward Sun

Longest daylight hours in Northern Hemisphere

Sun’s rays are at 90° at the Tropic of Cancer

Begins on September 22 or 23 Autumnal equinox

Neither pole is tilted toward the Sun Day and night are equal lengths

1. What are the causes of the seasons on Earth?2. What would our seasons be like if Earth’s axis

were not tilted?3. Explain why the Moon goes through phases as

seen from Earth.4. If Earth’s axis were tilted 45°, at what latitudes

would the Sun be directly overhead on the summer and winter solstices, and on the vernal and autumnal equinoxes?

Magnetosphere – earth’s magnetic field Sphere means around or surrounding

Geographic north is magnetic south Geographic south is magnetic north Earth’s magnetosphere comes from

movement of Fe (Iron) and Ni (Nickel) in the core

Rotation – one turn on its axis Revolution – one trip around the Sun

Perihelion – closest point to Sun Aphelion – farthest point from Sun

Time Zones – there are 24 standard time zones Ben Franklin invented Daylight Savings

Time move clocks ahead one hour in April, back to normal in October