As comets move close to the Sun, they develop tails of dust and ionized gas. Comets have two main tails, a dust tail and a plasma tail. The dust tail appears whitish-yellow because it is made up of tiny particles â about the size of particles of smoke â that reflect sunlight. Dust tails are typically between 1 and 10 million kilometers (about 600,000 to 6 million miles) long.
Hyperhidrosis, or excessive sweating, is a common disorder which produces a lot of unhappiness. An estimated 2-3% of Americans suffer from excessive sweating of the underarms (axillary hyperhidrosis) or of the palms and soles of the feet (palmoplantar hyperhidrosis). Underarm problems tend to start in late adolescence, while palm and sole sweating often begins earlier, around the age 13 (on the average). Untreated, these problems may continue throughout life. Sweating is embarrassing, it stains clothes, ruins romance, and complicates business and social interactions.
The palms of your hands and the soles of your feet have more sweat glands than any other part of your body. Some people have hands and feet that sweat a lot. This problem is common and can be very embarrassing. Sweaty hands and feet usually are not caused by a disease. This problem tends to begin in childhood.