How many?

Nautical Miles

A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters.Historically, it was defined as the meridian arc length corresponding to one minute (1/60 of a degree) of latitude. Today the international nautical mile is defined as exactly 1,852 metres. The derived unit of speed is the knot, one nautical mile per hour. To sail from Southampton to New York would cover a distance of around 3,081 nautical miles.

Nanometres

The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth (short scale) of a metre (0.000000001 m). To demonstrate just how small a nanometre is, it is commonly used to measure atoms and molecules. A typical virus is around 100 nanometres wide. The coronavirus, known as COVID 19 is believed to be between 60 to 120 nanometres wide.