The Exploration of Mars   Whatever was known about Mars till 1964 was based on the research work carried out by astronomers and scientists. In 1965 the Mariner-IV, an unmanned spacecraft, took the first pictures of Mars. Subsequent to this the Mariner-IX took close-up pictures of this desolate planet in 1971. Based on the data available from the pictures taken by these two space probes, the Viking-I and Viking-II unmanned spacecraft...

Why Are Stars Seen Only At Night? The atmosphere which surrounds the earth gives us the blue sky as we see in the daytime. Stars don’t disappear during daytime, it is just that they cannot be seen because of the Earth’s blue sky and the light from the Sun. If we were to stand on the Moon we would see the stars clearly since lack of air gives the sky a...

The Creation of Stars As we look up in the night sky we see close to 3000 different stars. They seem small but that is because of the distance, in reality they are as big as our Sun, some even bigger. Stars are generally born in clusters and are formed from thin clouds of hydrogen gas. As these clouds shrink, the hydrogen they contain gets compressed which increases the temperature and...

Comets Comets are visible at night and they look very much like meteors and meteorites but in reality they are different. When we see a comet in the sky we notice that it has a bright head and a glowing tail following it as it shoots across the sky. On a closer examination through a telescope we see a bright head, called the ‘coma’ and a large cloud of glowing dust...

Meteors and Meteorites A meteor is what we commonly known as a shooting star. Millions of small pieces of rock, some only as large as a marble, are orbiting the sun. On occasions, one of these pieces enters the Earth’s atmosphere. The friction it experiences while passing through the Earth’s atmosphere, at a speed of over 50 kilometres per second, causes it to burn up leaving a trail of white light...

The Constellations of Stars   Without the help of a telescope we can see about 6000 stars in the sky at night. Half of these can be seen in the northern sky and the other half in the southern sky. As we look at the stars we realise that we can form groups or shapes among them. These groups and shapes were mapped and classified by astronomers and given different names....

Galaxies in the Universe   It is estimated that the universe and its galaxies were formed some 15,000 million years ago due to a massive explosion. This theory of the astronomers is known as the ‘Big Bang Theory’. Since the ‘Big Bang’ the galaxies have been moving away from each other and the universe has been constantly expanding. Galaxies are large groups of stars, dust and gases, old stars are constantly...

The Milky Way The Milky Way is one of the many galaxies in the universe and the Sun is one of the 100 billion stars it has in it. The Milky way is so big in size that it takes light about 100 thousand years to travel from end to end. It tends to look patchy because in some parts of the galaxy the stars are closer to each other, as...