Scavengers help break down or reduce organic material into smaller pieces. These smaller pieces are then eaten by decomposers. Decomposers eat dead materials and break them down into chemical parts. ... They break down the organic material and recycle it into the ecosystem as nutrients.
“Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by- products and ATP is energy that is transformed from the process.”
Solar radiation, because it hasn't (at least noticeably) affected hawks.
One of the methods used widely to calculate the distance of nearby or closer objects in astronomy is Parallax. The distance of the stars are usually expressed in light years but the unit of distance is parsec or parallax second.
1 Parsec = 3.26 light years
Astronomers are not able to measure the parallax of a star that is a million light years away because the star is too far and the distance with which the start appears to move is too less to be calculated accurately.