How Old Is The Universe?

      The universe is about 13.8 billion years old . At its beginning it looked like nothing like it does today. Yet everything in today's universe did exist in some form back then. It all started with a Big Bang, a kind of explosion that would not only go on to produce all the matter in the Universe but also marked the same of time.

The universe is expanding by about 70km(43miles) every second.

What's in a Name?

     The term "Big Bang" was coined by Fred Hoyle in 1950 to illustrate to his radio listeners the difference between it and his own theory, "Steady State" where the universe has no beginning.

Nuclear reactions inside the stars produce many other chemical elements, including carbon and oxygen.

Will The Sun Shine For Ever?

        The sun is a star, a vast sphere of luminous gas. Its light is a by-product of gas-fuelled nuclear reactions in its core. It shines steadily now, but in about five billion years it will swell up before dying as a cold, dark cinder in space.

The sun is 332,945 times more massive than Earth, and 750 times more massive than all of the planets in the Solar System put together.

Elements in the Sun:

1) hydrogen                          71%

2) helium                            27.1%

3) oxygen                            0.97%

4) carbon                               0.4%

5) nitrogen                         0.096%

6) silicon                             0.099%

7) magnesium                   0.076%

8) neon                               0.058%

9) iron                                   0.14%

10) sulphur                          0.04%

You should never, ever look directly at the Sun. It emits dangerous radiation that can damage cells at the back of your eyes and cause blindness.

Are there other planets like Earth?

No, we don't know of any other planets exactly like Earth, with its unique life forms. But Earth has similarities to three other planets orbiting the Sun- Mercury, Venus and Mars. All four are made of rock and metal, orbit close to the Sun, and have relatively hot surfaces. They are known as the terrestrial or rocky planets.

Facts about Venus

* Venus is named after the Roman goddess of love and beauty.

 * It is surrounded by dense       clouds stretching up to 80km (50miles) above the surface.

 * Venus is hotter than Mercury despite being further away from the Sun.

Why does the Moon change shape?

     The Moon is a large ball of rock that doesn't change shape- it just looks as though it does. The shape we see in the sky today depends on how much of Moon's face is lit up. Sometimes we observe a thin crescent, and at other times we see half or three quarters of the Moon, and then a fully lit face- a full Moon.

How many Constellations are there?

    There are 88 constellations in the night sky. Each one is a straight edge area of sky that includes a pattern made from bright stars and they all fit together like pieces of a jigsaw to make up the entire sky around Earth.

The smallest constellation is Crux, the southern cross, which is also the brightest constellation.

The biggest constellation is Hydra, a water snake that meanders its way across 3.16 per cent of the whole sky.

References:

# Kinght, D., 2011. Ask me Anything. 1st ed. New York: Dorling Kindersley Limited, pp.8-25.