The temperature records also differ slightly because the point of reference that each group uses to calculate global temperature is different.

Using the light from 1, 857 stars, a team of French and American astronomers were able to measure the density of the gas surrounding our sun by examining fine differences in the starlight.

Calculated from the light - and dark-forward curve, usually gives you values that are slightly too low because the diode curves from the light and dark measurements are slightly different.