Partial-thickness burns (2nd degree burns)-- affect the top 2 layers of skin. Most notable by blisters (which may develop quickly or take 24 hours to form), but also red, mottled, wet and painful skin. Full-thickness burns (3rd degree burn)-- all three layers of skin affected; leathery, dry, charred, gray.
1 Discoveror: known since ancient times. 2  Place of discovery: not known. 3  Date of discovery: unknown. 4  Origin of name: from the Anglo-Saxon word  gold  (the origin of the symbol Au is the Latin word  aurum  meaning  gold ).
Astronomical unit (AU, or au) Astronomical unit (AU, or au), a unit of length effectively equal to the average, or mean, distance between Earth and the Sun, defined as 149,597,870.7 km (92,955,807.3 miles). Alternately, it can be considered the length of the semimajor axisâi.e., the length of half of the maximum diameterâof Earthâs elliptical orbit around the Sun.