Solar Eclipse

The Moon is a cold, rocky body about 2,160 miles (3,476 km) in diameter. It has no light of its own but shines by sunlight reflected from its surface. The Moon orbits Earth about once every 29 and a half days. As it circles our planet, the changing position of the Moon with respect to the Sun causes our natural satellite to cycle through a series of phases:

• New Moon > New Crescent > First Quarter > Waxing Gibbous> Full Moon > Waxing Gibbous > Last Quarter > Old Crescent > New Moon (again)

The phase known as New Moon can not actually be seen because the illuminated side of the Moon is then pointed away from Earth. The rest of the phases are familiar to all of us as the Moon cycles through them month after month. Did you realize that the word month is derived from the Moon's 29.5 day period?

The Moon's Two Shadows

An eclipse of the Sun (or solar eclipse) can only occur at New Moon when the Moon passes between Earth and Sun. If the Moon's shadow happens to fall upon Earth's surface at that time, we see some portion of the Sun's disk covered or 'eclipsed' by the Moon. Since New Moon occurs every 29 1/2 days, you might think that we should have a solar eclipse about once a month. Unfortunately, this doesn't happen because the Moon's orbit around Earth is tilted 5 degrees to Earth's orbit around the Sun. As a result, the Moon's shadow usually misses Earth as it passes above or below our planet at New Moon. At least twice a year, the geometry lines up just right so that some part of the Moon's shadow falls on Earth's surface and an eclipse of the Sun is seen from that region.

The Moon's shadow actually has two parts:

1. Penumbra

• The Moon's faint outer shadow.
• Partial solar eclipses are visible from within the penumbral shadow.

2. Umbra

• The Moon's dark inner shadow.
• Total solar eclipses are visible from within the umbral shadow.

When the Moon's penumbral shadow strikes Earth, we see a partial eclipse of the Sun from that region. Partial eclipses are dangerous to look at because the un-eclipsed part of the Sun is still very bright. You must use special filters or a home-made pinhole projector to safely watch a partial eclipse of the Sun.

From the part of Earth covered by the umbra (the darker,inner shadow), the Sun appears totally eclipsed. From the part of Earth covered by the umbra (the darker,inner shadow), the Sun appears totally eclipsed.

There are four types of solar eclipses:

A total eclipse occurs when the Sun is completely obscured by the Moon. The intensely bright disk of the Sun is replaced by the dark silhouette of the Moon, and the much fainter corona is visible. During any one eclipse, totality is visible only from at most a narrow track on the surface of the Earth.

http://www.youtube.com/watch?v=K42UqWGdA_o&feature=related



An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.


A hybrid eclipse is intermediate between a total and annular eclipse. At some points on the surface of the Earth it is visible as a total eclipse, whereas at others it is annular. Hybrid eclipses are rather rare.


A partial eclipse occurs when the Sun and Moon are not exactly in line, and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra never intersects the Earth's surface.

The "diamong ring" effect occurs seconds before and after a total eclipse begins and ends.

The Moon (Latin: Luna) is Earth's only natural satellite and the fifth largest natural satellite in the Solar System.

The Moon is the only celestial body to which humans have travelled and upon which humans have landed. The first artificial object to escape Earth's gravity and pass near the Moon was the Soviet Union's Luna 1, the first artificial object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The first spacecraft to perform a successful lunar soft landing was Luna 9, and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966. The United States (U.S.) Apollo program achieved the only manned missions to date, resulting in six landings between 1969 and 1972. Human exploration of the Moon ceased with the conclusion of the Apollo program, although several countries have announced plans to send people or robotic spacecraft to the Moon.

Luna 1

Luna 2

A series of Soviet Moon probes, including orbiters, landers, and sample-return craft, launched between 1959 and 1976. Lunas were the first manmade objects to reach escape velocity, crash into the Moon, photograph the Moon’s farside, soft land on the Moon, automatically return lunar surface material to Earth, and deploy a rover on the Moon’s surface.

Luna 3

Luna 9

On 20th July 1969, a man set foot on an extra-terrestrial surface for the very first time in History. This man was Neil Armstrong. Apollo 11 was the name of the first mission to land on the moon.A Saturn V launched Apollo 11 from the Kennedy Space Center on July 16, 1969 .

From the Apollo missions, we discovered how the Moon’s surface temperature can be extremely hot and extremely cold, depending on whether it is receiving sunlight or not. The Moon’s surface is also dry and chalky. However, orange rocks on the surface provide evidence of volcanic activity once in the Moon’s history. Most importantly, the Apollo missions proved that man can walk on another world, something that would have been unimaginable one hundred years earlier.

http://nssdc.gsfc.nasa.gov/imgcat/thumbnail_pages/moon_thumbnails.html

Neil Alden Armstrong (born August 5, 1930) is a former American astronaut, test pilot, university professor, and United States Naval Aviator. He is the first person to set foot on the Moon.

Neil Armstrong was the first, with Edwin Aldrin as the second man. Their footsteps remain on the surface of the Moon now and will remain there for million of years. After their first mission, a few months after, Apollo 12 landed two more astronauts on the Moon on 14th November. Apollo 13 headed for the Moon, but an explosion on the spacecraft caused the mission to be cancelled and the astronauts to have to return to the Earth, using a home-made piece of equipment to prevent poisonous carbon dioxide from building up in the spacecraft. Aftermath, four more missions landed men on the Moon, with Apollo17 being the last on 7th December 1972.

The Apollo 11 mission was the first manned mission to land on the Moon. It was the fifth human spaceflight of Project Apollo and the third human voyage to the Moon. Launched on July 16, 1969, it carried Commander Neil Alden Armstrong, Command Module Pilot Michael Collins and Lunar Module Pilot Edwin Eugene 'Buzz' Aldrin, Jr.

On July 20, Armstrong and Aldrin became the first humans to land on the Moon, while Collins orbited above. The mission fulfilled President John F. Kennedy's goal of reaching the moon by the end of the 1960s, which he expressed during a 1961 speech: "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth."

Landing of a man in the Moon


Picture of The Earth viewed from The Moon

The lunar module was named Eagle after the bald eagle depicted on the insignia; the bald eagle is the national bird of the United States. The command module was named Columbia, a traditional, feminized name for the United States used in song and poetry.
On July 20, 1969 the lunar module Eagle separated from the command module Columbia.

Command module

Buzz Aldrin spoke the first words (albeit technical jargon) from the LM on the lunar surface. Throughout the descent Aldrin had called out navigation data to Armstrong, who was busy piloting the LM. As Eagle landed Aldrin said, "Contact light! Okay, engine stop. ACA - out of detent." Armstrong acknowledged "Out of detent" and Aldrin continued, "Mode control - both auto. Descent engine command override off. Engine arm - off. 413 is in." Then Armstrong said the famous words, "Houston, Tranquility Base here. The Eagle has landed." Armstrong's abrupt change of call sign from "Eagle" to "Tranquility Base" caused momentary confusion at Mission Control.

After more than 2½ hours on the lunar surface, they had left behind scientific instruments such as a retroreflector array used for the Lunar Laser Ranging Experiment. They also left an American flag, an Apollo 1 mission patch, and a plaque (mounted on the LM Descent Stage ladder) bearing two drawings of Earth (of the Western and Eastern Hemispheres), an inscription, and signatures of the astronauts and Richard Nixon. The inscription read Here Men From The Planet Earth First Set Foot Upon the Moon, July 1969 A.D. We Came in Peace For All Mankind. They also left behind a memorial bag containing a gold replica of an olive branch as a traditional symbol of peace, the Apollo 1 patch, and a silicon message disk.

Aldrin entered Eagle first.While moving in the cabin Aldrin accidentally broke the circuit breaker that armed the main engine for lift off from the moon. There was initial concern this would prevent firing the engine, which would strand them on the moon. Fortunately a felt-tip pen was sufficient to activate the switch. Had this not worked, the Lunar Module circuitry could have been reconfigured to allow firing the ascent engine.

The moon is a cold, dry orb whose surface is studded with craters and strewn with rocks and dust (called regolith). The moon revolves around the Earth in about one month (27 days 8 hours). It rotates around its own axis in the same amount of time. The same side of the moon always faces the Earth; it is in a synchronous rotation with the Earth.

The moon has no atmosphere. On the moon, the sky is always appears dark, even on the bright side (because there is no atmosphere). Also, since sound waves travel through air, the moon is silent; there can be no sound transmission on the moon.


The surface of the moon is scarred by millions of (mostly circular) impact craters, caused by asteroids, comets, and meteorites. There is no atmosphere on the moon to help protect it from bombardment from potential impactors (most objects from space burn up in our atmosphere). Also, there is no erosion (wind or precipitation) and little geologic activity to wear away these craters, so they remain unchanged until another new impact changes it.

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. The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system.

This picture shows the Sun and all nine planets of the solar system as seen by the space explorers. Starting at the top-left corner is the Sun followed by the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths.

http://www.kidsastronomy.com/our_sun.htm

The Sun is the closest star to Earth and is the center of our solar system. A giant, spinning ball of very hot gas, the Sun is fueled by nuclear fusion reactions. The light from the Sun heats our world and makes life possible. The Sun is also an active star that displays sunspots, solar flares, erupting prominences, and coronal mass ejections. These phenomena impact our near-Earth space environment and determine our "space weather."

Mercury, the planet nearest the Sun, is the second smallest planet in the solar system. Only slightly larger than the Earth's moon, Mercury's surface is covered with craters. This tiny planet does not have any rings or moons.

Earth, our home planet, is a beautiful blue and white ball when seen from space. The third planet from the Sun, it is the largest of the inner planets. Earth is the only planet known to support life and to have liquid water at the surface.

Venus, a "Sister" planet to the Earth that is very different from our home. Venus does not have any moons or rings.

Mars, Earth's outer neighbor, is the fourth planet from the Sun. Mars' bright appearance and reddish color stand out in the night sky. Impressive surface features such as enormous volcanoes and valleys are frequently obscured by huge dust storms.

Jupiter is the largest planet in the solar system. When approached from afar, its fantastic striped atmosphere gradually reveals intriguing clouds that move around the planet. Rich in historical and cultural connections, Jupiter is the site of recent comet impacts and continuing scientific discovery.

Saturn, the sixth planet from the Sun, has the most spectacular set of rings in the solar system. We now know that Saturn has 59 moons in addition to its complex ring system.

Uranus is the seventh planet from the Sun and the third-largest and fourth-most massive planet in the solar system. Uranus is similar in composition to Neptune, and both have different compositions from those of the larger gas giants Jupiter and Saturn. As such, astronomers sometimes place them in a separate category, the "ice giants".
Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons.

Neptune, which is usually the eighth planet from the Sun, is a very cold place. Occasionally, the ninth planet Pluto crosses Neptune's orbit and becomes the "eighth planet". Its bluish color comes from its atmosphere of methane gas. The planet has 13 moons and a very narrow, faint ring system.

In 2006 the International Astronomical Union (IAU) approved a new classification scheme for planets and smaller objects in our Solar System. Their scheme includes three classes of objects: "small solar system bodies" (including most asteroids and comets), the much larger planets (including Earth, Jupiter, and so on), and the new category of in-between sized "dwarf planets".

There are currently three official dwarf planets. Pluto, formerly the smallest of the nine "traditional" planets, was demoted to dwarf planet status. Ceres, the largest asteroid in the main asteroid belt between Mars and Jupiter, was also declared a dwarf planet. The third and final (for now!) dwarf planet is Eris, an icy body on the edge of our Solar System that was discovered recently in 2005. Eris was temporarily labeled 2003 UB313 when it was first discovered, and given the nickname "Xena", before astronomers settled on the official name of Eris.

Comets are lumps of ice and dust that periodically come into the center of the solar system from somewhere in its outer reaches, and that some comets make repeated trips. When comets get close enough to the Sun, heat makes them start to evaporate. Jets of gas and dust form long tails that we can see from Earth. These tails can sometimes be millions of miles long.

Asteroids are small bodies that are believed to be left over from the beginning of the solar system 4.6 billion years ago. They are rocky objects with round or irregular shapes up to several hundred km across, but most are much smaller.

Meteors are streaks of light, usually lasting just a few seconds, which people occasionally see in the night sky. They are sometimes called "shooting stars" or "falling stars", though they are not stars at all. Meteors are caused by the entry of small pieces of rock, dust, or metal from space into the atmosphere at extremely high speeds. These particles, called "meteoroids" when they are floating around in space (think of very small asteroids), are traveling at incredible speeds of tens of kilometers per second (tens of thousands of miles per hour) when they streak into the atmosphere. The incredible pressure meteoroids experience when they collide with Earth's atmosphere shatters them, transferring energy to atoms and molecules in the atmosphere, which then release the energy by glowing. This glow produces the bright trails of light in the sky we see as meteors.

Most meteoroid particles are quite small, ranging in size from a grain of sand to a pea-sized pebble. Almost all of them disintegrate in the atmosphere long before reaching the ground. Very rarely, a larger meteoroid actually survives to strike the ground, creating a meteor crater in a huge explosion. This explosion often vaporizes whatever solid material is left of the meteoroid after its fiery flight through the atmosphere. Sometimes, however, pieces of the meteoroid survive and are found in the crater or nearby. These chunks of rock or metal are called meteorites.

In common usage, a constellation is a group of stars that are connected together to form a figure or picture..

A galaxy is a massive, gravitationally bound system consisting of stars, an interstellar medium of gas and dust, and dark matter. The name is from the Greek root galaxias , meaning "milky," a reference to the Milky Way galaxy. Typical galaxies range from dwarfs with as few as ten million stars up to giants with one trillion stars, all orbiting a common center of mass. Galaxies can also contain many multiple star systems, star clusters, and various interstellar clouds. The Sun is one of the stars in the Milky Way galaxy; the Solar System includes the Earth and all the other objects that orbit the Sun.

The Universe is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term "universe" may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world or Nature.

Globe is a hollow sphere representing Earth and illustrated with the continents, seas, and islands, especially one showing and labeling the countries

The World is a proper noun for the planet Earth envisioned from an anthropocentric or human world view, as a place inhabited by human beings. It is often used to signify the sum of human experience and history, or the 'human condition' in general.The world population is over 6.80 billion people.

Earth is the only place in the universe where life is known to exist. Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land.

Earth's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 71% of the surface is covered with salt-water oceans, the remainder consisting of continents and islands; liquid water, necessary for all known life, is not known to exist on any other planet's surface. Earth's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.

A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary.

Earth has only one natural satellite, the Moon. But thousands of small artificial satellites have also been placed in orbit around the Earth.

Earth is the third planet from the Sun and the fifth largest:

    orbit:    149,600,000 km (1.00 AU) from Sun    
    diameter: 12,756.3 km 
    mass:     5.972e24 kg

The earth consists of seven continents listed as follows: North America, South America, Antarctica, Africa, Europe, Asia and Australia; the largest of which is Asia.

71 Percent of the Earth's surface is covered with water. Earth is the only planet on which water can exist in liquid form on the surface (though there may be liquid ethane or methane on Titan's surface and liquid water beneath the surface of Europa). Liquid water is, of course, essential for life as we know it. The heat capacity of the oceans is also very important in keeping the Earth's temperature relatively stable. Liquid water is also responsible for most of the erosion and weathering of the Earth's continents, a process unique in the solar system today (though it may have occurred on Mars in the past)

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