Solar system, relative position of Earth with respect to Sun and other planets, movement of earth and moon in solar system, lunar and solar eclipses

The solar system consists of the Sun and its eight main planets, their satellites, asteroids, comets, meteors and other dwarf planets. The Sun is at the one of the two “centers” of the Solar system and the planets revolving around it in elliptical orbits.

The sun is in the centre of the solar system. It is huge and made up of extremely hot gases. It provides the pulling force that binds the solar system. The sun is the ultimate source of heat and light for the solar system. The sun is about 150 million km away from the earth.The Sun is made up of 73% hydrogen and 25% helium. It also has trace amounts of oxygen, carbon, iron and other elements. It is about 4.6 billion years old and will continue to shine for another 5 billion years. After that it will grow into a Red Giant and then finally end its life as a white dwarf.

Earth and the moon, sun, and planets have predictable patterns of movement. These patterns, which are explainable by gravitational forces and conservation laws, in turn explain many large-scale phenomena observed on Earth. Planetary motions around the sun can be predicted using Kepler’s three empirical laws, which can be explained based on Newton’s theory of gravity. These orbits may also change somewhat due to the gravitational effects from, or collisions with, other bodies. Gradual changes in the shape of Earth’s orbit around the sun (over hundreds of thousands of years), together with the tilt of the planet’s spin axis (or axis of rotation), have altered the intensity and distribution of sunlight falling on Earth. These phenomena cause cycles of climate change, including the relatively recent cycles of ice ages.

The orbits of planets and of their moons, of asteroids and of comets are governed by the gravitational force and described by the three Kepler’s laws.Kepler formulated three laws which govern the motion of planets. These are:

1. The orbit of a planet is an ellipse with the Sun at one of the foci

keplers-first-law

2. The area swept by the line joining the planet to the sun in unit time is constant through out the orbit

3. The square of the period of revolution of a planet around the sun is proportional to the cube of its average distance from the Sun. If we denote the period by T and the average distance from the Sun as r, T2 ? r3 .

The Earth orbits around the Sun and Moon around the earth, so when the Earth comes between Moon and the Sun then Moon passes through the Earth’s shadow, it is called a Lunar Eclipse. As most of us know that Moon is not self illuminated but it reflects Sunlight falling on it. During Lunar Eclipse light coming from the Sun is blocked by the Earth, and directly it does not reach up the Moon so, moon’s brightness, reduced very much. Moon’s brightness is not totally vanished because, some indirect light from earth’s atmosphere reaches up to the Moon so it remains visible up to some extent

In a partial lunar eclipse, part of the Moon is within the Earth’s umbral shadow. From the Earth, we see the Moon partially in shadow, almost as if it wasn’t full. In the later stages of a partial eclipse, as the Moon darkens, red coloration may become visible on the shadowed side of the Moon. A total lunar eclipse is when the Moon is completely shadowed by the Earth. The Moon passes through the Earth’s umbra, and no direct light can reach it from the Sun.

A solar eclipse occurs when the moon passes in a direct line between the Earth and the sun. The moon’s shadow travels over the Earth’s surface and blocks out the sun’s light as seen from Earth.

Different types of solar eclipses

• A total eclipse occurs when the dark silhouette of the Moon completely obscures the intensely bright light of the Sun, allowing the much fainter solar corona to be visible.

• 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 surrounding the dark disk of the Moon.

• A hybrid eclipse shifts between a total and annular eclipse. At certain points on the surface of Earth it appears as a total eclipse, whereas at other points it appears as annular. Hybrid eclipses are comparatively rare.

• A partial eclipse occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun.

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