# How can I get curated data to be expressed consistently in SI units?

AstronomicalData objects are consistently in SI units:

AstronomicalData["Mars", "Radius"]
(* Quantity[3.386*10^6, "Meters"] *)

AstronomicalData["Mars", "Density"]
(* Quantity[3934.0, ("Kilograms")/("Meters")^3] *)


However, PlanetData objects are not consistent anymore (miles are not cgs!):

PlanetData["Mars", "Radius"]
(* Quantity[2104., "Miles"] *)

PlanetData["Mars", "Density"]
(* Quantity[3.9340, ("Grams")/("Centimeters")^3] *)


Is there any way to force Mathematica into using consistent units and, even better, into SI units? I do not want to use UnitConvert as this makes the code really unreadable, what I want is curated data delivered in SI units.

• At least, PlanetData["Mars", "Radius"] will now return a result in kilometers. – J. M. is in limbo May 31 '16 at 9:54

\$UnitSystem = "Metric"

SetOptions[WolframAlpha, PodStates -> {"Show metric"}]

• Thank you, that at least gives answers in km instead of miles. However, the inconsistency is still there (cgs for PlanetData and SI for AstronomicalData). – leosenko Sep 16 '15 at 18:37