The distance between the Sun and Earth is not a fixed number because Earth's orbit is elliptical. It varies throughout the year.

Here's the information you need to calculate it:

* Average distance: 149.6 million kilometers (93 million miles)

* Closest approach (perihelion): 147.1 million kilometers (91.4 million miles)

* Furthest distance (aphelion): 152.1 million kilometers (94.5 million miles)

To convert these distances to millimeters, you'd multiply by 1,000,000,000 (1 billion).

So, for example, the average distance in millimeters would be:

149.6 million kilometers * 1,000,000,000 millimeters/kilometer = 149,600,000,000,000,000 millimeters