The Earth In The Solar System - Class 6 Geography - Extra Questions

A small rocky body orbiting the sun. Large numbers of these, ranging enormously in size, are found between the orbits of Mars and Jupiter, though some have more eccentric orbits.

A meteoroid is a small rocky or metallic body in outer space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to one-meter-wide objects. Objects smaller than this are classified as micrometeoroids or space dust.  

A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. 

The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. 

Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. 

However, most of the estimated 300 sextillions (3×10²³)stars in the observable universe is invisible to the naked eye from Earth, including all-stars outside our galaxy, the Milky Way.

Stars are celestial objects that can produce their own light. They are extremely hot and extremely large in size. They are mostly made up of hydrogen gas with a little helium in them. The sun is also a star; the sun’s energy and light play one of the key roles in sustaining all forms of life on earth.

Stars produce light by nuclear fusion reactions that happen inside it. In this process hydrogen is converted into helium and energy is produced as a byproduct. It is this energy that comes to us as light. The sun is near to us appears large and very bright in the sky. However, all other stars are extremely far away from us. So, they appear small and faint in the sky. In fact, many of these celestial bodies are hundreds of times bigger than our sun in size and much brighter but they don’t appear so because they are so far away from the earth.

They are present in the sky even during the day. We do not see them because the sun’s bright light hides them. There are billions of them in the universe, more than all the grains of sand in the earth.

Orbits are elongated fixed paths in which a celestial body always remains.

Meteors burn up when they hit the Earth's atmosphere. 

When the meteor hits the atmosphere, the air in front of it compresses incredibly quickly. When a gas is compressed, its temperature rises. This causes the meteor to heat up so much that it glows.

Venus is similar to earth in its size and shape. Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period of any planet in the Solar System and rotates in the opposite direction to most other planets. It does not have any natural satellites. It is named after the Roman goddess of love and beauty. 

As one of the brightest object t in the sky, Venus has been a major fixture in human culture for as long as records have existed. It has been made sacred to gods of many cultures, and has been a prime inspiration for writers and poets as the morning star and evening star. Venus was the first planet to have its motions plotted across the sky, as early as the second millennium BC.

Venus has been a prime target for early interplanetary exploration. It was the first planet beyond Earth visited by a spacecraft , and the first to be successfully landed on Venus's thick clouds render observation of its surface impossible in visible light, and the first detailed maps did not emerge until the arrival of the Magellan orbiter in 1991. Plans have been proposed for more complex missions, but they are hindered by Venus's hostile surface conditions.

Planetai-"wanderers", from which today's word "planet" was derived. In ancient Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the universe and that all the "planets" circled Earth. 

The reasons for this perception were that stars and planets appeared to revolve around Earth each day and the apparently common sense perceptions that Earth was solid and stable and that it was not moving but at rest.

Jupiter is the largest planet in the solar system. Fittingly, it was named after the king of the gods in Roman mythology. In a similar manner, the ancient Greeks named the planet after Zeus, the king of the Greek pantheon.

Jupiter helped revolutionize the way we saw the universe and ourselves in 1610, when Galileo discovered Jupiter's four large moons. This was the first time that celestial bodies were seen circling an object other than Earth, major support of the Copernican view that Earth was not the center of the universe.

Saturn is the sixth planet from the sun and the second-largest in the solar system, after Jupiter. It is a gas giant with an average radius about nine times that of Earth It has only one-eighth the average density of Earth, but with its larger volume Saturn is over 95 times more massive. Saturn is named after the roman god of agriculture; its astronomical symbol represents the god's sickle.

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 naptune, and both have bulk chemical compositions which differ from that of the larger gas giants jupiter and saturn.

Stars are celestial objects that can produce their own light. They are extremely hot and extremely large in size. They are mostly made up of hydrogen gas with a little helium in them. The sun is also a star; the sun’s energy and light play one of the key roles in sustaining all forms of life on earth.

Stars produce light by nuclear fusion reactions that happen inside it. In this process hydrogen is converted into helium and energy is produced as a by product. 

It is this energy that comes to us as light. The sun being near to us appears large and very bright in the sky. However, all other stars are extremely far away from us. So, they appear small and faint in the sky. In fact, many of these  celestial bodies  are hundreds times bigger than our sun in size and much brighter but they don’t appear so because they are so far away from the earth.

They are present in the sky even during the day. We do not see them because the sun’s bright light hides them. There are billions of them in the universe, more than all the grains of sand in the earth.

Constellations of Stars:

Because the earth revolves around its axis from west to east, the stars all appear to move east to west like the sun. In the night sky they seem to appear as groups called as constellations forming a particular pattern in the sky. In reality, stars in constellations can be billions of kilometers apart. They only appear to be close when viewed from the earth.

Our solar system includes Sun, planets, satellite etc. but we have other members also which play a very important role in the existence of universe the way it exists today. Let us briefly discuss about the other members of the solar system.

The solar system is huge in size at least a 100 Astronomical Units in size (15 trillion km). It is held together by the sun’s immense gravitational pull that keeps objects like the planets and the asteroids in orbit around it.

The solar system also contains 8 planet which are large almost spherical objects that revolve around the sun in elliptical paths known as orbits. 

The earth is also one of the planets and lies at a distance from the sun such that it is neither too hot nor too cold for life to exist. 

The planets were formed at least 4.6 billion years ago when discs of dust and gas orbiting around the sun collapsed and clumped together due to gravity. There are two kinds of planets:

1. Rocky planets include Mercury, Venus, Earth and Mars which are mostly made up of solid rock and metal.
2. Gas giants include Jupiter, Saturn, Uranus and Neptune which are mostly made up of gases like Hydrogen, Helium, Methane etc. These planets are very large in comparison to the rocky planets.

The solar system also contains small irregularly shaped objects made of rock, metal and carbon called  Asteroid or biting the sun. Most of these objects lie between the orbits of Mars and Jupiter in the asteroid belt.

Asteroids

These are big chunks of rock or metal that are mostly found orbiting the Sun between Mars and Jupiter. It is believed that these moons did not originally orbit Mars, but were instead a part of the Asteroid belt. 

Satellites

Satellites are objects that revolve around planets and are also part of the solar system. The Earth’s satellite is the Moon. Some satellites like Ganymede are bigger than Mercury and can have atmospheres.

Comets

Comets are small irregularly shaped objects made up of ice. They usually come from the outer most reaches of the solar system beyond Neptune from a region known as the Kuiper Belt. 

When these objects come close to the sun, the ice vaporizes forming a beautiful tail behind them.

Dwarf planets

Dwarf planets are objects smaller than planets and larger than asteroids that orbit the sun at various places. The nearest dwarf planet to us is Ceres which lies in the asteroid belt. The most famous is Pluto which lies beyond Neptune on the inner edge of the Kuiper belt. In 2014, Pluto and its 5 satellite were visited by a spacecraft named New Horizons for the first time in history capturing images of the icy dwarf planet in high resolution.