A star is located at$<6\times {10}^{10},8\times {10}^{10},6\times {10}^{10}>$m. A planet is located at$\mathbf{<}\mathbf{-}\mathbf{4}\mathbf{\times }{\mathbf{10}}^{\mathbf{10}}\mathbf{,}\mathbf{-}\mathbf{9}\mathbf{\times }{\mathbf{10}}^{\mathbf{10}}\mathbf{,}\mathbf{6}\mathbf{\times }{\mathbf{10}}^{\mathbf{10}}\mathbf{>}$m. (a) What is the vector pointing from the star to the planet? (b) What is the vector pointing from the planet to the star?

Star m

Planet m

(a) Here the tail of the vector will be on the star, and the head of it is on the planet, and the position vector between these two points could be found by subtracting the position of the tail from the position of the head.

Thus, the required vector is m.

(b) The vector pointing from the planet (position of the tail) to the star (position of the head) is the result of subtracting the position of the planet from the position of the star (or simply it is the negative of the position vector from the star to the planet).

Therefore, the required vector is m.