The cluster has distorted the shape of the galaxy from a spiral shape to a more arc-shaped. Astronomers are certain the blue-shaped objects are copies of the same galaxy because the shapes are similar. Here we will look at the way in which gravity is able to provide huge amounts of power, before looking at the sources themselves. Questions in blue can be clicked to reveal the answers, but to test your understanding and engage your brain, it is best to consider your own answer before clicking.
Gravity is a very weak force compared to electrical forces.
2 is a good approximation except in regions of extremely strong gravity. This force is referred to as the weight of the body. It is not the same as its mass , it doesn't even have the same units. Orbits and weightlessness A striking illustration of the difference between weight and mass is the behaviour of bodies in orbit. Most of the general public believe that this weightlessness is due to the fact that the astronauts are a long way from Earth, which is the source of the gravity.