Original sentence: The amount of solar radiation received at the outer surface of Earth's atmosphere varied little from an average value of 1366 watts per square meter (W/m<sup>2</sub>).The variations in total solar output remained at or below the threshold of detectability until the satellite era, although the small fraction in ultra-violet wavelengths varies by a few percent
Edited sentence: The amount of solar radiation received at the outer surface of Earth's atmosphere varies little from an average value of 1366 watts per square meter (W/m<sup>2</sub>).The variations in total solar output are so slight (as a percentage of total output) that they remained at or below the threshold of detectability until the satellite era, although the small fraction in ultra-violet wavelengths varies by a few percent