Hi, my name is Stefan. Today, I'm going to be speaking on how scientists know the mass of Mars, okay Mars is a planet here, we'll call this M, M for Mars and there's a satellite that travels around Mars, it's actually called Dimos and it travels around it in a circle and this radius I'll call it R and we have the time that it takes to go around it, we'll call that T and we use the formula, T = the square root of 4 Pi squared R cubed/G/M and G is the gravitational pull and M is the mass and now when we solve we get M or the mass of Mars, that's equivalent to, I'm going to use scientific notation, 6.4169 x 10 to the 23 kilograms. And this is our mass of Mars.