International Ultraviolet Explorer was considered the most successful astronomical satellite ever. The human eye can perceive light with wavelengths between roughly 350 (violet) and 700 (red) nanometres. Ultraviolet light has wavelengths between roughly 10 nm and 350 nm. UV light can be harmful to human beings, and is strongly absorbed by the ozone layer. This makes it impossible to observe UV emission from astronomical objects from the ground. Many types of object emit copious quantities of UV radiation, though: the hottest and most massive stars in the universe can have surface temperatures high enough that the vast majority of their light is emitted
Day of the Sun leaders. Festivities are not confined to the date. Commemorations occur from 16 February, which is the birthday of Kim Jong-il, during what is known as the Loyalty Festival. Celebrations in April around the Day of the Sun are called the Sun Festival. The day itself is followed by two days of rest, making it a three-day holiday. Kim Il-sung was born on 15 April 1912 in the village of Mangyongdae, which is now a suburb of North Korea's capital Pyongyang. He has been long identified with the Sun and is frequently called "Sun of the nation". He adopted his name