Friday, 9 December 2011



1) A comet is made of dirty ice, dust, and gas.

2)When a comet gets close to the Sun, part of the ice starts to melt. The solar winds then push the dust and gas released by the melting ice away from the comet. This forms the comet's tail. Every time a comet comes close to the Sun, a part of it melts. Over time, it will completely disappear.

3)A comet does not give off any light of its own. What seems to be light from the comet is actually a reflection of our Sun's light. Sunlight bounces off the comet's ice particles in the same way light is reflected by a mirror.

4)A few comets come close enough to the Earth for us to see them with our eyes. Halley's Comet, for example, can be seen from Earth every 76 years.




1)A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's (or another body's) atmosphere is called a meteor, or colloquially a shooting star or falling star.

2)If a meteoroid reaches the ground and survives impact, then it is called a meteorite. Many meteors appearing seconds or minutes apart are called a meteor shower.


meteor shower



1)Asteroids are the many small rocky or metallic objects which are flying in the Solar System.

2)Asteroids are mostly found in a belt located between the orbits of Mars and Jupiter.

3) This area is sometimes called the "asteroid belt". Think about it this way: the asteroid belt is a big highway in a circle around the Sun. Think about the asteroids as cars on the highway. Sometimes, the asteroid cars run into one another. When this happens, the asteroids may break up into


Natural Satellites---The Moon

The Moon: Earth's Satellite
The Moon is the only place in our solar system, other than Earth, where humans have visited. On July 20, 1969, astronauts Neil Armstrong and Edwin Aldrin landed the Lunar Module of Apollo 11 on the Moon's surface. Neil Armstrong was the first human to set foot on the Moon.

The Moon is like a desert with plains, mountains, and valleys. It also has many craters, which are holes created when space objects hit the Moon's surface at a high speed. There is no air to breathe on the Moon. Recently water ice was discovered at the poles (or top and bottom) of the Moon. The ice is buried beneath some of the dust of the Moon's surface. Scientists think the ice may be left over from a comet that once collided with the Moon.

The Moon travels around the Earth in an oval shaped orbit. Scientists think the Moon was formed long ago when Earth collided with another space object. The collision may have caused a big chunk of rocky material to be thrown out into space to form the Moon.
The Moon is a little lopsided. Its crust is thicker on one side than the other. The Moon is much smaller than the Earth. However, the pull of its gravity can still affect the Earth's ocean tides.
We always see the same side of the Moon from Earth. You have to go into space to see the other side.

Learn About The Planet


The planet Mercury is the closest of the planets to the Sun. Because this planet lies so close to the Sun, and as a result somewhat near to Earth, it is visible to observers on Earth in the late evening or early morning sky. Because of this, Mercury has become a part of the mythology and legend of almost every culture throughout the history of the Earth.                                         

This planet is often called a morning star. This is because Mercury shines brightly in the early morning just before the sun rises. It has also been called an evening star for the same reason. Mercury is often visible for a brief period of time just after the Sun sets.
Mercury Has No Atmosphere The planet Mercury is too small and has too little gravity to hold onto an atmosphere. Any gases released from the planet quickly escape into space. Also, Mercury is so close to the Sun that any atmosphere is quickly blown away by the Sun's solar winds. That means that there is almost no air on Mercury.

Venus: Earth's Twin

Venus is called the Evening Star. It is called this because it looks so bright to us from Earth.


Venus and Earth are almost the same size. Venus is the closest planet to Earth, but it does not have oceans or human life like Earth. Venus gets so hot during the day that it could melt a lead cannonball. The temperature rises to 484 degrees Celsius on the side facing the Sun. Venus has very thick, rapidly spinning clouds which cover its surface. These clouds hold heat in. That is why Venus gets so hot. These clouds also reflect sunlight. That is why Venus appears so bright to us here on Earth. There are constant thunderstorms in these clouds. Venus has several large inactive volcanoes. Much of the surface is covered by old lava flows from these volcanoes.

Venus is unusual because it rotates in a direction opposite that of all of the other planets. Venus spins very slowly as it orbits the Sun

Earth: The Water Planet
Seventy percent of the Earth's surface is covered by water. The remaining 30 percent is covered by mountains, volcanoes, deserts, plains, and valleys.

Earth is the third closest planet to the Sun. It has an atmosphere made up of many different gases, but mainly it is nitrogen and oxygen. The atmosphere gives us air to breathe. We live on the planet Earth.
The Earth orbits around the Sun. It takes one year to go around the Sun one complete time. The Earth also rotates, or spins, on its axis. It takes one day to spin around one complete time. The Earth's axis is not straight up and down, but tilted a little bit. This tilt is responsible for us having seasons. Otherwise, the temperature would be pretty much the same all year long.
Rotating Earth

Mars: The Red Planet
Some of the meteorites found on Earth are actually pieces of the planet Mars. As of June 2006, thirty-four "Martian meteorites" have been found.

The temperature on Mars can be very, very cold. On its warmest day, Mars can still be a very cold place. At the top and bottom of the planet are poles just like on Earth. During the Martian winter, ice caps can be seen at the poles.
Space probes have landed on Mars. These probes were sent on a fact-finding mission by the United States. They performed experiments on the Martian dirt and atmosphere. The dirt was found to contain clay which was rich in iron. The iron is what gives Mars its red color.
Mars has many craters which were formed by meteorites or asteroids hitting it. Mars also has some of the tallest volcanoes and some of the deepest valleys in our solar system. Mars has two moons, Phobos and Deimos which have unusual shapes. Scientists think these potato-shaped moons were once asteroids captured by Mars' gravitational pull .
Jupiter: The Largest Planet
Jupiter is so large that all of the other planets in the solar system could fit inside of it.

Jupiter is a large gas planet whose clouds change colors daily. This planet is made mostly of hydrogen and helium gases. Jupiter gives off two times more heat than it gets from the Sun. It shines very brightly in the night sky for nine months of the year when it is closest to Earth. Huge areas of swirling gases can be found in Jupiter's atmosphere. The largest swirling area of gas is called the Great Red Spot. Scientists believe this is a large hurricane-like storm which has lasted for hundreds of years. Large bolts of lightning have also been seen in Jupiter's atmosphere. Pictures taken by space probes have shown thin rings around Jupiter. As of January 2011, Jupiter has 50 named moons. 13 more have been discovered but not given official status or names. One of Jupiter's moons, Io, has active volcanoes on it. Areas on Io that are near the volcanoes are very, very hot.

Saturn: The Ringed Planet
When seen through a telescope, Saturn is one of the most beautiful sights in the night sky. It looks like a big ball inside of rings.


Saturn is a very large gas planet which spins very rapidly on its axis. It spins so fast that it flattens out the top and the bottom of the planet. The fast spin also causes Saturn to bulge at its equator. Saturn's atmosphere has winds which can blow at over 1800 kilometers per hour! The white spots on Saturn are believed to be powerful storms. Saturn is surrounded by over 1000 rings made of ice and dust. Some of the rings are very thin and some are very thick. The size of the particles in the rings range from pebble-size to house-size. Scientists believe that the particles came from the destruction of moons circling the planet. As comets and meteorites smashed the moons, Saturn's gravitational pull shaped the particles into rings. Saturn has at least 53 moons. Some of these moons orbit the planet within the rings, creating gaps in the rings.
Uranus: Neptune's Twin
Uranus is one of the smaller gas giants in our solar system, but it is still large enough to hold 64 planets the size of Earth.

Uranus tilts over so far on its axis that it rotates on its side. Because of this, its poles are sometimes pointed almost directly at the Sun. Uranus' atmosphere is made up of hydrogen, helium, and methane. The temperature in the upper atmosphere is very cold. The cold methane gas is what gives Uranus its blue-green color. The rapid rotation of Uranus causes winds up to 600 kilometers per hour to blow in its atmosphere. Uranus has eleven known rings which contain dark, boulder-sized particles. Uranus has 27 named moons. Some of these moons are less than 100 kilometers wide and black as coal.

Neptune: The Blue Planet
It is so cold on Neptune that you would need skin thicker than a polar bear's to stay warm.
Neptune and Uranus are very much alike. They are both large gas planets that look like big blue-green balls in the sky. Neptune has winds in its atmosphere which blow at over 2000 kilometers per hour! This planet has large, dark circles on its surface which astronomers believe to be storms. Neptune has two thick and two thin rings which surround it. Neptune also has thirteen known moons. Four of these moons orbit the planet within the rings. One of Neptune's moons, Triton, orbits the planet in a direction opposite to Neptune's other moons. Neptune is the farthest planet from                                             the Sun.

Eight Planets In The Solar System

An Introduction...
In our solar system, eight planets circle around our Sun. The Sun sits in the middle while the planets travel in circular paths (called orbits) around it. These nine planets travel in the same direction (counter- clockwise looking down from the Sun's north pole). The picture above shows the different paths and positions of each planet (not to scale).

The solar system is made up of two parts:
The inner solar system contains Mercury, Venus, Earth and Mars. These four planets are closest to the Sun.
The outer solar system contains Jupiter, Saturn, Uranus and Neptune
The inner planets are separated from the outer planets by the Asteroid Belt.

How big are they?

 As you might expect, dwarf planets are smaller than major planets. Even Earth's Moon is bigger than the dwarf planets.
  • Earth is 7,926 miles in diameter.
  • Earth's Moon is about 2,100 miles in diameter.

How far away are they?

Earth is third outward from the Sun. Neptune is eighth. Pluto is ninth. Now, Pluto is downgraded in its classification to dwarf leaving only eight planets of the Solar System described as major.

Earth is only 93 million miles from the Sun, while Pluto's average distance from the Sun is 3.6 billion miles. At 9.7 billion miles, Eris is three times farther from the Sun than Pluto.
Neptune's diameter is about 30,775 miles.

Planets: How Big, How Far?
in miles
Sun Distance
in miles
Mercury3,03236 million
Venus7,54367 million
Earth7,92693 million
Mars4,217142 million
Jupiter88,732483 million
Saturn74,975870 million
Uranus31,7631.8 billion
Neptune30,7752.8 billion
Pluto1,4293.7 billion


19.1 The Constituents Of The Solar System


1.The Sun is a small star.The Sun is located at the centre of the Solar System

The Sun's core can reach 10 to 22.5 million°F. The surface temperature is approximately 9,900°F (5,500°C). The outer atmosphere of the Sun (which we can see during a solar eclipse) gets extremely hot again, up to 1.5 to 2 million degrees. At the center of big sunspots the temperature can be as low as 7300 °F (4300 K, 4000 °C). The temperature of the Sun is determined by measuring how much energy (both heat and light) it emits.