Ch 27 The Sun-Earth-Moon System Page 764

27.1 Tools of Astronomy Radiation -Light is the most common term for electromagnetic radiation. -Visible light makes up a small portion of the electromagnetic spectrum. Found in the ESRT’s -The shorter the wave length the more intense the radiation is. -ROYGBIV the colors of the rainbow Red has the long wave length and violet has the shortest.

27.1 Tools of Astronomy Telescopes are tools used to extend our sense of sight. Refracting telescopes: Uses lenses to bring light into focus. Reflecting telescope: Uses mirrors to bring light into focus

27.1 Tools of Astronomy Telescopes can also use other wave lengths such as: -Infrared -Ultraviolet -Radio -X-rays Interferometry: The process of linking separate telescopes together so that they act as one telescope.

27.1 Tools of Astronomy Satellites and space based telescopes have one major advantage over Earth bound telescopes. The telescopes in space do not have to look through Earth’s atmosphere which can distort the images. This is an image from the Hubble telescope pictured below

Which was the first country to make it into space in 1957? 27.2 The Moon Which was the first country to make it into space in 1957? The Soviet union with Yuri Gagarin below in Sputnik right

27.2 The Moon Which country was the first and only country to land a man on the moon in 1969? The US with Neil Armstrong (right)and Buzz Aldrin (below) Apollo (right)

Neil Armstrong - “One small step for man, One giant leap for mankind” 27.2 The Moon Neil Armstrong - “One small step for man, One giant leap for mankind”

28.2 The Moon Moon notes: -Albedo: The amount of sun light that a surface reflects based on the color and texture. -The Moons albedo is very small at 7%

28.2 The Moon -The moon has no natural light of its own but reflects the light given from the Sun. -Impact craters: the marks left on the moon’s surface from objects in space striking the moon -These craters remain visible because there is no atmosphere on the moon to weather away these marks.

27.2 The Moon The moons phases are predictable and can be determined years in advance.

F.Y.I What is a Blue moon? When two full moons occur in the same month.

28.2 The Moon Highlands: Are the light colored mountainous regions covered with craters. Maria: Dark smooth plains on the lunar surface Impact craters: Craters created when objects from space struck the lunar surface Ejecta: Material that blasted out during impacts and fell back to the surface Rays: Trails of ejecta that radiate outward Rilles: Meandering valley like craters

27.2 The Moon Composition: The moon is made up of minerals similar to Earth-Mostly silicates but little iron. -The age of the moon is between 3.6 and 4.6 billion years old (found using radiometric dating). Regolith: The layer of loose ground up rock and averages several meters in thickness.

F.Y.I Several years ago a man was arrested for trying to sell moon rock that he stole. The Moon rocks value is estimated about 1,000 to 5,000 per gram and would have sold for around 7 million dollars!

27.2 The Moon After a serious bombardment of meteorites, magma flowed up to the surface (becoming lava) and created the Maria.

27.2 The Moon Tectonics on the Moon -The Moon has a similar structure to that of the Earth -The upper mantle is solid while the lower mantle is partially molten. -The Moon experiences Moonquakes -Current theory states that the Moon is not tectonically active

The Moon Three Formation Theories: 1. Capture theory: When the solar system was forming a large object came to close to Earth and was caught in the gravitational pull. Problems: a) Something would have to slow this object down first (inertia in space). b) The composition of the Moon are too similar to be a coincidence. A captured object would have a different composition in the crust.

The Moon Three Formation Theories: 2. Simultaneous Formation theory: The Earth and the Moon formed at the same time in the same general location. This solves problem of having to slow down the Moon and explains similar composition. Problem: a) Does not explain why the Earth has a lot of iron and the Moon does not.

The Moon Three Formation Theories: 3. Impact Theory *The most commonly accepted theory. -A mars sized object hit the Earth as it was developing. -The iron on the Earth at this time sunk to the center due to its high density. -The object struck Earth and ejected the iron deficient outer layer which formed the moon. -This solves the problems with the other theories.

27.3 The Sun-Earth-Moon System -The rotation (spinning) of the earth causes night and day. -360 degrees in a sphere and there are 24 hours in a day. Divide 360 by 24 and you get: -A rate of 15 degrees per hour. -Evidence of Earth’s rotation can be seen with a pendulum and is also observed by the Coriolis effect. -Our time keeping is based on a solar day (sun rise to sun set).

27.3 The Sun-Earth-Moon System -It takes about 365 days to complete an orbit around the Sun. -Ecliptic: The term for the plane on which the Earth orbits. -The Earth’s tilt is 23 and 1/2 degrees. -This is why the tropics are between 23 1/2 degrees North and South latitude. -The Sun’s altitude changes with the seasons and is over head at noon between these two latitudes no matter what season it is. -When we are tipped towards the Sun in the northern hemisphere it is our summer.

27.3 The Sun-Earth-Moon System -A solstice occurs when the Earth is tilted towards or away from the Sun. -The Summer solstice occurs when we are tilted towards the Sun on June 21 our longest day. -The Winter solstice is Dec 21 our shortest day. -The equinox (equal night in Latin) occurs when both hemispheres receive an equal amount of Sun light -The autumnal equinox September 21 -The Vernal (spring) equinox March 21

27.3 The Sun-Earth-Moon System Phases of the Moon -The new moon phase occurs when the moon is between the Earth and the Sun. -The full moon occurs when the moon is on the direct opposite side of the Earth as the new moon and Sun.

28.3 The Sun-Earth-Moon System Synchronous rotation: The state at which the Moon’s orbital period and rotational period are equal. -This is why we always see the same side of the Moon.

27.3 The Sun-Earth-Moon System Synchronous rotation: The state at which the moons orbital period and rotational periods are equal. -This is why we always see the same side of the Moon.

27.3 The Sun-Earth-Moon System -The Lunar cycle is about 29.5 days. -It takes about 27.3 days for one revolution around Earth. -The Moon rises and sets about 50 minutes later each day. -The moon moves 13 degrees in its orbit over a days time.

27.3 The Sun-Earth-Moon System Tides: The cyclic and predictable movement of the Earth’s Oceans as it rises and falls at 12 hour intervals. -Tides are a product of the Moons gravitational pull on Earth’s oceans. -The Sun’s effect on the tides is about 1/2 as much as the moon because the Sun is so far away.

27.3 The Sun-Earth-Moon System Neap tides: created when the Sun and Moon are at right angles to the Earth and lower than normal tides are produced.

27.3 The Sun-Earth-Moon System Spring tides: Larger than normal tides produced when the Moon and Sun are in alignment and are pulling in the same direction.

27.3 The Sun-Earth-Moon System Solar Eclipse: When the Sun’s light is blocked by the new Moon.

27.3 The Sun-Earth-Moon System Lunar Eclipse: When the Moon’s light is blocked by Earth’s shadow.

27.3 The Sun-Earth-Moon System Why is it that we do not have an eclipse every month??? The orbital plane of the Moon is at a 5 degree tilt compared to the orbital plane of the Earth (ecliptic). The moons orbit is elliptical around the Earth. Perigee: When the Moon is closest to the Earth. Apogee: When the Moon is at its farthest point from Earth.

Ch 27 Quiz 1. What is the most common term for electromagnetic radiation? 2. How did the moon most likely form? 3. What is the rotation rate of the Earth (in degrees per hour)? 4. Draw and label a diagram of the Moon, Earth and Sun during a lunar eclipse. Bonus: What is the term when the Moon is closest to the Earth?

Ch 27 Quiz 1. Draw a diagram of the Earth around the Sun showing the beginning of each of the 4 seasons. Show the tilt and label the date. 2. Draw a diagram showing the position of the Sun, Earth, and Moon for both spring tides and neap tides. Label each one. 3. Draw a diagram showing the Moon, Earth and Sun during a Full moon. 4. Why do we always see the same side of the Moon? Bonus: Why do we not have an eclipse every month?