Defined model
Pick one particular grain from the Sahara
- Probability:
- 1.25 × 10⁻²²%
- Odds:
- 1 to (7.98 × 10²³)
- dBan
- −239 dBan
Mark one grain in the modelled Sahara and choose uniformly from them all: the chance of returning to it is about one in 798 sextillion.
Calculation
p = 1 in 7.98 × 10²³. N = 9.4 × 10¹² × 0.20 × 10 × 0.60 / ((π/6) × 0.0003³)
Assumptions
The model uses a total area of 9.4 million km², with dunes covering 20% to an assumed depth of 10 m. Grains are modelled as 0.3 mm spheres with 60% solid packing.