A Square Meter at the Top of Earth's Atmosphere, Aligned

Multiple Choice

A square meter at the top of Earth's atmosphere, aligned perpendicular to the Sun's rays at a distance of 1 AU from the Sun, receives 1,362 watts. Researchers refer to this number, 1,362 watts/m², as the ____________ constant because it has varied by less than 0.2% over the last 400 years.

A) lithium
B) solar
C) gravity
D) fission