Gravitational Fields

Newton's law of gravitation

Every point mass attracts every other with a force proportional to the product of their masses and inversely proportional to the square of their separation:

$$F = \dfrac{G m_1 m_2}{r^2}$$

where $G = 6.67\times10^{-11}\ \text{N m}^2\,\text{kg}^{-2}$ is the gravitational constant. The force is always attractive.