In scientific notation, if the exponent of 10 is positive, the number is very very large. In the metric system, very large numbers are expressed in megameters (Mm) or gigameters (Gm). Gigameters is equal to 10⁹ meters. So, in SI prefix, that would be equal to 150 Gm. In kilometers, that would be equal to:
1.5×10¹¹ m * (1 km/1000 m) = 1.5×10⁸ km
