Clouds, atmospheric aerosols, snow, ice, sand, ocean surface and even rooftops play a role in deflecting the incoming rays. The remaining 70 percent of solar energy is absorbed by land, ocean, and atmosphere. "Greenhouse gases block about 40 percent of outgoing thermal radiation that emanates from Earth," Woods said.
Mercury's seasons are difficult to determine. This is because it has virtually no tilt (0.03 degrees), but a highly elliptic orbit. ... Mercury also has a bizarre rotation, spinning three times (every 53 Earth days) over two rotations around the Sun, making it impossible to tell when one season begins and one ends.
you can find the answer by dividing the total distance it travels by the total time elapsed in its travel.
found : http://www.answers.com/Q/What_is_an_object's_total_distance_traveled_divided_by_the_total_time_it_tr...
