The Solar System is the Sun and the objects that orbit the Sun. These are a planetary system (of eight planets) and various secondary bodies: dwarf planets and other small objects that orbit the Sun directly, as well as satellites (moons) that orbit many planets and smaller objects. The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant molecular cloud.
SOLAR SYSTEM
Neptune
Uranus
Neptune, the outermost planet in the Solar System, cannot be seen from Earth without a telescope or binoculars. It is covered by icy, bright blue methane clouds that whip around the globe at speeds of more than 700mph (1,100km/h).
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both are of different chemical composition than the larger gas giantsJupiter
Earth
Mars
Earth is the third planet from the Sun. It is the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world or the Blue Planet.
Mars is the fourth planet from the Sun and the second smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often described as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance.
Saturn
and Saturn.
Mercury
Jupiter
Venus
Mercury is the smallest and closest to the Sun of the eight planets in the Solar System, with an orbital period of about 88 Earthdays.
Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth of that of the Sun but is two and a half times the mass of all the other planets in the Solar System combined.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. It is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows.
PLANETS
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter.
Distance to Earth: 384,400 km Orbital period: 27 days Gravity: 1.622 m/s² Age: 4.527 billion years Circumference: 10,917 km Orbits: Earth
he Moon is the only natural satellite of the Earth and the fifth largest moon in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, having 27% the diameter and 60% the density of Earth, resulting in 1â „81 its mass. Among satellites with known densities, the Moon is the second densest, after Io, a satellite of Jupiter. The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic mariathat fill between the bright ancient crustal highlands and the prominent impact craters. It is the brightest object in the sky after theSun, although its surface is actually dark, with a reflectance just slightly higher than that of worn asphalt
The Moon is the only celestial body other than Earth on which humans have set foot. The Soviet Union's Luna programme was the first to reach the Moon with unmanned spacecraft in 1959; the United States' NASA Apollo program achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings between 1969 and 1972, with the first being Apollo 11. These missions returned over 380 kg of lunar rocks, which have been used to develop a geological understanding of the Moon's origins, the formation of its internal structure, and its subsequent history.
THE MOON
In both astrology and historical astronomy, the zodiac is a circle of twelve 30째 divisions of celestial longitude that are centered upon the ecliptic: the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets also remain close to the ecliptic, within the belt of the zodiac, which extends 8-9째 north or south of the ecliptic, as measured in celestial latitude. Because the divisions are regular, they do not correspond exactly to the twelveconstellations after which they are named.
ZODIAC
Although the zodiac remains the basis of the ecliptic coordinate system in use in astronomy besides the equatorial one, the term and the names of the twelve signs are today mostly associated with horoscopic astrology.
The Antikythera mechanism is an ancient analog computer designed to predict astronomical positions and eclipses. It was recovered in 1900–1901 from theAntikythera wreck, a shipwreck off the Greek island of Antikythera. Although the computer's construction has been attributed to the Greeks and dated to the early 1st century BC, its significance and complexity were not understood until a century after its recovery, when, at 1970s, it was analyzed with modern X-ray technology. Technological artifacts approaching its complexity and workmanship did not appear again until the 14th century, when mechanical astronomical clocks began to be built in Western Europe.
The front dial is marked with the divisions of the Egyptian calendar, or the Sothic year. Inside this there is a second dial marked with the Greek signs of the Zodiac. This second dial is moveable dial so that it can be adjusted to compensate for leap years. The front dial probably carried three hands, one showing the date, and two others showing the positions of the Sun and the Moon. The Moon indicator is ingeniously adjusted to show the fist anomaly of the Moon's orbit. It is reasonable to suppose the Sun indicator had a similar adjustment. The front dial also includes a second mechanism with a spherical model of the Moon that displays its phase. There is reference in the inscriptions for the planets Mars and Venus, and it would have certainly been within the capabilities of the maker of this mechanism to include gearing to show their positions. There is some speculation that the mechanism may have had indicators for the 5 planets known to the Greeks. Finally the front dial includes a parapegma used to mark the rising and setting of specific stars. Each star is thought to be identified by Greek characters which cross references details inscribed on the mechanism. The upper back dial, is in the form of a spiral, with 47 divisions per turn, displaying the 235 months of the 19 year Metonic cycle. This dial contains a smaller subsidiary dial which displays the 76 year Callippic cycle. (There are 4 Metonic cycles, within 1 Callippic cycle.) Both of these cycles are important in fixing calendars. The lower back dial is also in the form of a spiral, with 223 divisions showing the Saros eclipse cycle. It also has a smaller subsidiary dial which displays the 54 year Exeligmos cycle. (There are 3 Saros cycles, within 1 Exeligmos cycle.)
ANTIKYTHERA MECHANISM