gravity On Earth there is a simple rule what goes up must come down If I jump in the air or throw a ball really high I know that the ball and I will always return back to the ground This is because of gravity which is an invisible force that pulls us down to the ground Gravity always pulls things together but never pushes things apart If there was no gravity on Earth then we would all float around which would make it difficult to eat and drink or see our friends GRAVITY KEEPS US ON THE GROUND EVERYTHING IN ITS RIGHT PLACE The more massive a thing is the more force it exerts on us We all stay on the surface of the Earth because it is the biggest thing that is nearest to us The sun is so big that it exerts a huge force due to gravity 4 This gravitational pull keeps our planets together so they don’t fly off into outer space and that is why the planets stay in orbit
KEEPING OUR MOON IN THE SKY Our Moon stays in orbit around the Earth because of the Earth’s gravity Our moon is always trying to fly away but the gravity of our Earth keeps it flying around us YAHOO ON THE MOON JUMPING ON THE MOON ground but much slower than you would on Earth Gravity is smaller on the Moon because the Moon is smaller than the Earth This means you are able to jump much higher there You would still come back down to the ON THE EARTH WHO DISCOVERED GRAVITY We know about gravity because of very curious people called scientists that explore test and think about how everything works around us Isaac Newton was a scientist who discovered how gravity works he realised that gravity was acting on everything from an apple falling from a tree to the planets moving around the Sun So before we begin our adventure let’s understand what a scientist does FOR GRAVITY’S SAKE Gravity is the reason the Earth and the Sun were created from clouds of dust and gas floating around in space Gravity started to pull them together until they collapsed in on themselves and as they fell inwards they became increasingly compact and turned into the stars and planets we see around us today
Science is the study of the world around us and scientists are people who look at the world and ask some very simple questions about it What is everything made of Why does everything move the way it does Why is everything arranged this way rather than any other way the scientific method In order to answer these questions scientists go out and investigate the world by performing experiments An experiment is a test we carry out on something in the world to see if it will behave the way we think it will For example we might like to find out where rainbows come from Perhaps you’ve noticed that rainbows only seem to appear when there is sunshine and rain in the sky at the same time So we might guess that some combination of sunshine and rain causes a rainbow In scientific terms this guess is called a hypothesis
To see if our hypothesis is right or not we can conduct an experiment Let’s try creating our own rain using a spray of water from a hosepipe first spraying the water on a sunny day where we expect to make a rainbow and then spraying the water on a cloudy day where we don’t expect to make a rainbow HOW ABOUT TRYING THIS EXPERIMENT YOURSELF WHAT DO YOU THINK WILL HAPPEN SUNNY DAY CLOUDY DAY When we do this experiment we are collecting scientific results If these results match our guesses then our hypothesis is correct If not we will have to go back to the drawing board and try to work out what else might be causing the rainbows This is what scientists do all the time They make a hypothesis about how the world works and then design an experiment to test it When a hypothesis proves to be true scientists explain why it is true using a theory
