127944
The intensity of solar thermal energy from solar radiation at the surface of the earth is about , of area normal to the direction of the sun , under clear-sky conditions .
 earth, sun
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 earth, sun