A Presentation by:Jeannie Arcos

CHAPTER 9:

Earth, Moon and Sun

Early Astronomy• Human beings are curious creatures. They have a

natural desire to seek explanations for the existence of things. To the first people to exist, much of what existed on Earth would have been a mystery to them. The objects in space that we now know as stars, planets, moons and comets would have completely baffled them. But by looking at them and trying to understand them, these early human beings would become the first astronomers.

Pictures Depicting Early Astronomy

Eratosthenes

Eratosthenes was a Greek mathematician who is famous for his work on prime numbers and for measuring the diameter of the earth

Earth-Moon-Sun System

The Moon does not produce any light of its own—it only reflects light from the Sun. As the Moon moves around the Earth, we see different parts of the near side of the Moon illuminated by the Sun. This causes the changes in the shape of the Moon that we notice on a regular basis, called the phases of the Moon. As the Moon revolves around Earth, the illuminated portion of the near side of the Moon will change from fully lit to completely dark and back again.

Rotation and RevolutionRotation is when a planet or moon turns all the way around or spins on its axis one time. The axis of rotation is an imaginary line going from the north pole to the south pole. When a planet or moon travels once around an object this is considered a revolution. On Earth, a rotation is pretty short - it happens once a day! It is the rotation that makes the sun appear to come up in the morning and set at night. On Earth, a revolution is quite a bit longer - one year!

The Moon

The moon is the easiest celestial object to find in the night sky — when it's there. Earth's only natural satellite hovers above us bright and round until it seemingly disappears for a few nights. The rhythm of the moon's phases has guided humanity for millennia — for instance, calendar months are roughly equal to the time it takes to go from one full moon to the next.

EclipsesAn eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.

A solar eclipse occurs when the new moon passes directly between the Earth and the Sun. This casts a shadow on the Earth and blocks our view of the Sun.

Solar Eclipse

A total solar eclipse occurs when the Moon's shadow completely blocks the Sun. When only a portion of the Sun is out of view, it is called a partial solar eclipse. Solar eclipses are rare events that usually only last a few minutes. That is because the Moon's shadow only covers a very small area on Earth and Earth is turning very rapidly. As the Sun is covered by the moon's shadow, it will actually get cooler outside. Birds may begin to sing, and stars will become visible in the sky. During a solar eclipse, the corona and solar prominences can be seen.

Lunar Eclipse

A lunar eclipse occurs when the full moon moves through the shadow of the Earth. This can only happen when the Earth is between the Moon and the Sun and all three are lined up in the same plane, called the ecliptic. The ecliptic is the plane of Earth's orbit around the Sun. The Earth's shadow has two distinct parts: the umbra and the penumbra. The umbra is the inner, cone shaped part of the shadow, in which all of the light has been blocked. The outer part of Earth's shadow is the penumbra where only part of the light is blocked. In the penumbra, the light is dimmed but not totally absent. A total lunar eclipse occurs when the Moon travels completely in Earth's umbra. During a partial lunar eclipse, only a portion of the Moon enters Earth’s umbra. A penumbral eclipse happens when the Moon passes through Earth’s penumbra. The Earth's shadow is quite large, so a lunar eclipse lasts for hours and can be seen by anyone with a view of the Moon at the time of the eclipse.

After World War II drew to a close in the mid-20th century, a new conflict began. Known as the Cold War, this battle pitted the world’s two great powers–the democratic, capitalist United States and the communist Soviet Union–against each other. Beginning in the late 1950s, space would become another dramatic arena for this competition, as each side sought to prove the superiority of its technology, its military firepower and–by extension–its political-economic system.

The Race for Space

The Apollo ProgramThe Apollo program, also known as Project Apollo, was the third United States human spaceflight program carried out by the National Aeronautics and Space Administration(NASA), which accomplished landing the first humans on the Moon from 1969 to 1972.

Chapter 10:

The Solar System

Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; and the interplanetary medium.

Ptolemy was the most influential of Greek astronomers and geographers of his time. He propounded the geocentric theory that prevailed for 1400 years.

Claudius Ptolemy

Galileo Galilei, was an Italian astronomer, physicist, engineer, philosopher, and mathematician who played a major role in the scientific revolution during the Renaissance.

Galileo Galilei

Tycho Brahe, born Tyge Ottesen Brahe, was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations. He was born in Scania, then part of Denmark, now part of modern-day Sweden.

Tycho Brahe

Johannes Kepler December 27, 1571 – November 15, 1630) was a German Mathematician, astronomer, and astrologer. A key figure in the 17th century scientific revolution, he is best known for his laws of planetary motion.

Johannes Kepler

English physicist and mathematician Sir Isaac Newton, most famous for his law of gravitation, was instrumental in the scientific revolution of the 17th century.

Iaac Newton

It is often said that the Sun is an "ordinary" star. That's true in the sense that there are many others similar to it. But there are many more smaller stars than larger ones; the Sun is in the top 10% by mass. The median size of stars in our galaxy is probably less than half the mass of the Sun.

The Sun

The inner planets (in order of distance from the sun, closest to furthest) are Mercury, Venus, Earth and Mars. After an asteroid belt comes the outer planets, Jupiter, Saturn, Uranus and Neptune. The interesting thing is, in some other planetary systems discovered, the gas giants are actually quite close to the sun.

The Inner Solar System

Asteroids are small, airless rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. In total, the mass of all the asteroids is less than that of Earth's moon. But despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future.

Asteroids

Meteors

A meteor is a bright streak of light in the sky (a "shooting star" or a "falling star") produced by the entry of a small meteoroid into the Earth's atmosphere.

The outer planets are those planets in the Solar System beyond the asteroid belt, and hence refers to the gas giants, which are in order of their distance from the Sun: Jupiter is the largest planet in the Solar System. It has four very large satellites.

The Outer Solar System

The astronauts had to use special tools to collect rock samples on the Moon because they could not bend over in their spacesuits.

Space Travel

Chapter 11:

STARS AND GALAXIES

LensesLenses form images by refraction and are typically made of either glass or plastic. They are ground so that their surfaces are either segments of spheres or planes. If a lens is convex or converging, it takes parallel light rays from a distant object and bends them so that they converge to a single point called the focal point. The distance from the lens to the focal point is called the focal length of the lens.

The earliest telescopes, as well as many amateur telescopes today, use lenses to gather more light than the human eye could collect on its own. They focus the light and make distant objects appear brighter, clearer and magnified.

Telescopes

A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescopedesign was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses.

Refracting Telescope

A reflecting telescope (also called a reflector) is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image.

Reflecting Telescope

As everybody knows distances in astronomy are vast with many people struggling to understand the extremely large numbers involved and the methods Astronomers use to calculate distances. It must be said here that there is no single method able to be used to calculate the distance to the entire Astronomical phenomena that have been discovered.

Astronomical Distances

When the light from a galaxy which is moving away from you is observed the wavelength of the observed light appears longer, it moves towards the red end of the spectrum. This is called RED SHIFT.

Red Shift

Red shift supports the big bang theory.The big bang theory is that the universe began from a very small initial point. The universe then expanded from that point to give us the universe we see today.The light from distant galaxies is red shifted (this tells us the galaxies are moving away from us) and the further away the galaxy the greater the red shift (this tells us that the more distant the galaxy the faster it is moving).

THE BIG BANG THEORY

A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Other stars, mostly in the Milky Way, are visible from Earth during the night, appearing as a multitude of fixed luminous points due to their immense distance.

Stars

Life Cycle of Stars

A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

Galaxies

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