The Moon is the Earth's natural satellite which has circled around it for at least four billion years. It is actually a rocky ball about a quarter of the Earth's size and is held in its orbit by mutual gravitational attraction. Scientists believed that the Monn formed when early in the Earth's history, a planet smashed into it. The impact was so great and tremendous that nothing was left of the planet but a few hot splashes thrown back up into space. Within a day of the smash, these splashes had been drawn together by gravity to form the Moon.

The first men on the Moon were Neil Armstrong and Buzz Aldrin of the US Apollo 11 mission who landed on the Moon on 21 July 1969. (As Neil Armstrong once said, "This a small step for a man, a giant leap for mankind.")

The large dark pitches visible on the Moon's surface are called seas, but in fact they are not seas at all. They are huge plains formed by lava flowing from volcanoes that erupted early on in the Moon's history.

It takes the Moon approximately 27.3 days to circle the Earth, but 29.53 days from one full moon to the next as the Earth moves as well. A lunar month is the 29.53 days cycle. Calendar months are entirely artificial.

As the Moon revolves round the Earth, sometimes it passes right into the Earth's shadow, where sunlight is blocked off. This is a lunar eclipse. So if you look at the Moon during this period of time, you will see the dark disc of the Earth's shadow creeping across the Moon.

The Moon is by far the brightest object in the night sky. However, it does not give off its own light. Hence, it simply reflects off the Sun light to produce moonlight.

The harvest moon is the full moon nearest to the autumnal equinox (when night and day are of equal length). This moon hangs bright above the eastern horizon for several evenings, providing a good light for harvesters.

 - Why does the sea have tides?

The Moon's gravity draws the oceans into an oval around the Earth, creating a bulge of water on each side of the world. These bulges stay beneath the Moon as the Earth spins around and seem to run around the world, making the tide rise and fall as they pass.

Now, let watch a video on the formation of the Moon:

URL: http://www.youtube.com/watch?v=v6A3BzWdd_o&feature=related

Around four and a half billion years ago, neither the Earth nor any of the other planets existed. There was just this vast dark very hit cloud of gas and dust swirling around the newly formed Sun. Gradually, the cloud cooled down and the gas began to condense into billions of water droplets. Slowly, these droplets then were pulled together into clumps by their own gravity - and they were carried on clumping until all the planets, including Earth, were formed. But it took about another half a billion years before the Earth had cooled enough to form a solid crust with an atmosphere around it.

An Earth day is the time when the Earth takes to rotate on its axis once. The stars come back to the same place in the sky every 23 hours 56 minutes 4.09 seconds (the sidereal day). Our day (the solar day) is 24 hours as the Earth is moving round the Sun and it must turn an extra 1 degree for the Sun to return to the same place in the sky.

In the 1500s, most people thought that the Earth was fixed at the centre of the universe, with the Sun and the stars revolving around it. However, Nicolaus Copernicus (1473 - 1543) was the polish astronomer who first suggested that the Earth was actually revolving around the Sun and not the other way round.

After reading about the instruments used in Astronomy, I think you might be interested to know more about another topic which seems to be confused by most people with Astronomy. This term is Astrology (this might be your first time hearing this word, right?).

However, there is no evidence to support their belief that stars and planets have any effect on our personalities or our destinies. Astronomers now thnik Astrology is just superstition. However, its original noble motives should not be forgetten. For most of the so-called "Dark Ages", when all pure science was in deep hibernation and the desire to know about the future that kept the science of Astronomy alive.

Until the discoveries of modern medicine, ancient people believed that the body was governed by four main different types of essence which were called "humours". An imbalance in these humours would result in illnesses. Each of the 12 signs of the horoscopes had special links with each of the hmours and with parts of the human body. One example is for a headache due to the moisture in the head (a cold), treatment would be with a drying agent - some plant ruled by the Sun or an "Earth sign", like Virgo -when a New Moon was well placed towards the sign of Aries, which ruled the head.

Most of the constellations are now known by the Latinized versions of their original Greek names. This card shows Scorpius, or Scorpio. This is the sign "through which" the Sun passes between late October and late November. Astrologers believe that people born during this time of year are intuitive, yet secretive, like a scorpion scuttling under a rock.

Cancer, the Crab

Cancer is supposed to be a home-body, like a crab in its shell. These hand-painted cards are collectively known as Urania's Mirror - Urania is the name of the muse of astronomy. By holding the cards up to the light, it is possible to learn the shapes and relative brightness of the stars in each constellation.

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The astronomical facts of the relatively regular interval of the day, the constancy of the movements of the fixed stars, and the assumption of certain theories, such as a spherical Earth, allowed people to measure their lives. By calculating the height of the Sun or certain stars, the ancient Greek began to understand the shape and size of the Earth. In this way, they were able to determine their latitude. By plotting coordinates against a globe, they could fix their position on the Earth's surface. In addition, by setting up carefully measured markers, or gnomons, they could begin to calculate the time of the day.

As the Sun travels across the sky, the shadow which it casts changes in direction and length. A sundial works by setting a gnomon, or "indicator", so that the shadow which the Sun casts at noon falls due north/south along a meridian. (A meridian is an imaginary line running from pole to pole and another for it is a line of longitude.)

The hours can then be divided before and after the noon mark. Hence, the terms "a.m." and "p.m." for morning and night actually originated from the Latin words meaning before and after the Sun passes the north/south meridian. So "a.m." actually refers to "ante meridiem" and "p.m." refers to "post meridiem"!

The backstaff allowed a navigator to measure the height of the Sun without having to stare directly at it. The navigator held the instrument so that the shadow cast by the shadow vane would fall directly on to the horizon vane. Moving the sight vane, the navigator lined it up so he could see the horizon through the sight vane and the horizon vane. By adding together the angles of the sight and shadow vanes, the navigator could calculate the altitude of the Sun, from which he could determine the precise latitude of his ship.

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As Astronomy is the oldest of the sciences, it has a long history which evolves from one stage of life to another.

In ancient times, early cultures identified celestial objects with gods and spirits. They related these objects (and their movements) to phenomena such as rain, drought, seasons, and tides. It is generally believed that the first "professional" astronomers were priests (such as the Magi), and that their understanding of the "heavens" was seen as "divine", hence astronomy's ancient connection to what is now called astrology. Ancient structures with possibly astronomical alignments (such as Stonehenge) probably fulfilled both astronomical and religious functions.

In the ancient times, calendars of the world would have usually been set by the Sun and Moon (measuring the day, month and year) and were of importance to agricultural societies, in which the harvest depended on planting at the correct time of year. The most common modern calendar is based on the Roman calendar, which divided the year into twelve months of alternating thirty and thirty-one days apiece. In 46 BC Julius Caesar instigated calendar reform and adopted a calendar based upon the 365 1/4 day year length originally proposed by 4th century BC Greek astronomer Callippus.

The spread of knowledge tends to follow the two routes of trade and war. As great empires were expanding, they eventually brought their gods, customs, and learning with them. The earliest civilisation believed that the stars and planets were actually ruled by gods. How amazing!

One example is the Babylonians named each planet after the god which they believed had most in common with that planet's characteristics. In addition, the Greeks and the Romans soon adopted this Babylonian system, replacing the names of the planets with those of their gods. Hence, all planet names can be traced directly to the Babylonian planet-gods such as: Nergal has become Mars, and Marduk has become the god Jupiter. 

The earliest astronomical records are in the form of clay tablets from ancient Mesopotamia, the "land between the rivers" Tigris and Euphrates, where the ancient kingdoms of Sumer, Assyria, and Babylonia were located. A form of writing known as cuneiform emerged among the Sumerians around 3500-3000 BC. Our knowledge of Sumerian astronomy is indirect, via the earliest Babylonian star catalogues dating from about 1200 BC. The fact that many star names appear in Sumerian suggests a continuity reaching into the Early Bronze Age. Astral theology, which gave planetary gods an important role in Mesopotamian mythology and religion, began with the Sumerians. They also used a sexagesimal (base 60) place-value number system, which simplified the task of recording very large and very small numbers. The modern practice of dividing a circle into 360 degrees, of 60 minutes each, began with the Sumerians.

Classical sources frequently use the term Chaldeans for the astronomers of Mesopotamia, who were, in reality, priest-scribes specializing in astrology and other forms of divination.

The first evidence of recognition that astronomical phenomena are periodic and of the application of mathematics to their prediction is Babylonian. Tablets dating back to the Old Babylonian period [disambiguation needed] document the application of mathematics to the variation in the length of daylight over a solar year. Centuries of Babylonian observations of celestial phenomena are recorded in the series of cuneiform tablets known as the Enūma Anu Enlil. The oldest significant astronomical text that we possess is Tablet 63 of the Enūma Anu Enlil, the Venus tablet of Ammi-saduqa, which lists the first and last visible risings of Venus over a period of about 21 years and is the earliest evidence that the phenomena of a planet were recognized as periodic. The MUL.APIN, contains catalogues of stars and constellations as well as schemes for predicting heliacal risings and the settings of the planets, lengths of daylight measured by a water-clock, gnomon, shadows, and intercalations. The Babylonian GU text arranges stars in 'strings' that lie along declination circles and thus measure right-ascensions or time-intervals, and also employs the stars of the zenith, which are also separated by given right-ascensional differences.

A significant increase in the quality and frequency of Babylonian observations appeared during the reign of Nabonassar (747-733 BC). The systematic records of ominous phenomena in astronomical diaries that began at this time allowed for the discovery of a repeating 18-year cycle of lunar eclipses, for example. The Greek astronomer Ptolemy later used Nabonassar's reign to fix the beginning of an era, since he felt that the earliest usable observations began at this time.

The last stages in the development of Babylonian astronomy took place during the time of the Seleucid Empire (323-60 BC). In the third century BC, astronomers began to use "goal-year texts" to predict the motions of the planets. These texts compiled records of past observations to find repeating occurrences of ominous phenomena for each planet. About the same time, or shortly afterwards, astronomers created mathematical models that allowed them to predict these phenomena directly, without consulting past records. A notable Babylonian astronomer from this time was Seleucus of Seleucia, who was a supporter of the heliocentric model.

Babylonian astronomy was the basis for much of what was done in Greek and Hellenistic astronomy, in classical Indian astronomy, in Sassanian Iran, in Byzantium, in Syria, in Islamic astronomy, in Central Asia, and in Western Europe.

Do you know that the earliest astronomers were actually shepherds who watched the heavens for signs of the changing seasons! Those clear nights would have given them the opportunity to recognize familiar patterns and movements of the brightest heavenly bodies.