I am currently in an astronomy class, and we are learning about gravity. We learned how to calculate the difference of gravity in different planets and stars. The formula is gravity = mass ÷ (radius)^2.  As an example, we calculated the difference in gravity between the Earth and the moon. The moon is about 1/10 the mass of Earth and about 1/4 the radius. To figure out the difference, you much plug in the numbers into the equation. (g=gravity  m=mass  r=radius  ☾=moon  O=earth)

g☾=m☾÷(radius☾) ^2=(mO/10)÷(rO/4)^2=16/100gO

In pain English, this formula helps show us that the moon has about 16% of the gravity of Earth meaning in comparison, a jump would be higher and you’d feel lighter. What helps determine gravity of a planet, star, or moon, is its size, radius, and distance from the sun. As a planet’s mass increases with all else constant, the jump will be shorter meaning more gravity; as mass decreases with all else constant, the jump will be higher meaning less gravity. As the radius of a planet increases with all else constant, the jump will double the amount the radius increased (if it increases x3, your jump will increase x9), meaning less gravity. As the radius decreases, all else constant, the jump will decrease in height meaning more gravity.

This subject seemed extremely relevant to last week’s topics of comparisons in sizes and measurements because this subject helps us compare levels of gravity in the solar systems and puts them in laymen’s terms. Also, we had previously looked at the scale of different things in our solar system, so the subject seemed reasonable.

Resource: ASTRO Notes from the class and Video game from the class.