How are plants and animals related? What is the Universe made of? And just what is the big secret behind it all? Find out all about the mysteries which scientists have been exploring for thousands of years.

1 In the beginningThe universe was created from a very tiny and incredibly hot ball of energy. Scientists call this 'The Big Bang' but the creation was very quiet as there was no air to carry the sound. When people later appeared. they used science as a way to find out what was going on. Scientists would carry out experiments, collect and compare samples, and use telescopes to see the stars.2 Heavenly bodiesThe universe is very big. There are so many stars, planets and moons in it than we could ever count. There are also things in the universe called black holes that are so heavy and massive that they suck light into themselves. Galaxies are formed when stars group together in massive clusters. Our solar system has one sun and eight planets including Earth.3 Life as we know itAll the different kinds of living things on Earth contain DNA inside them. Living things that share similar features are put together in a group. Millions of tiny living things, like bacteria, can live in plants and animals. All living things need food to build up their bodies and they can also reproduce which means they can make babies.4 The smallest thingsAll living things have millions of tiny building blocks called cells. Microscopes are used to see the cells in your body. Computers are not living things but they are also made up of tiny building blocks called microchips. Molecules are the tiny things that make up everything. Most molecules are too small to be seen with a microscope. Molecules are made of even smaller bits called atoms.5 The secret behind everythingEnergy is what makes atoms do anything. It never appear or disappears but it can be changed from one kind to another. Nuclear power stations find energy by splitting atoms into pieces. This is called nuclear fission. The nuclear energy that is released is used to make electricity. Solar panels change light energy into electricity. 6 Mixed reactions Molecules that are made of just one kind of atom are known as elements. Chemical reactions happen when two elements are mixed together and this creates a whole new substance. Chemical reactions can also separate elements from each other. Elements are listed in a chart called 'The Periodic Table'.7 Putting things togetherUnderstanding how things work mean that amazing things can be built like robots that do jobs that too dangerous or too boring for people. Altering the DNA of living things can lead to new kinds of plants and animals with special abilities. Discoveries that happen accident can be used create amazing things and examples of such accidental discoveries are penicillin and x-rays.8 See into the futureKnowing everything about how the world works would allow scientists to predict the future very accurately. 9 What's whatBranches of science include cosmology, entomology, quantum physics, mechanical engineering, dendrology, informatics, and meteorology.