Rainbow flag India during the week of Amartithi (the anniversary of his death on January 31, 1969). Rainbow is used as an element of flag of Patriots of Russia (Russian: Патриоты России, "Patrioty Rossii") political party. This rainbow flag in Italy was first used in a peace march in 1961, inspired by similar multi-coloured flags used in demonstrations against nuclear weapons. It became popular with the "Pace da tutti i balconi" ("peace from every balcony") campaign in 2002, started as a protest against the impending war in Iraq. The most common variety has seven colours, purple, blue, azure, green, yellow, orange and
Rainbow In Europe, Ibn al-Haytham's "Book of Optics" was translated into Latin and studied by Robert Grosseteste. His work on light was continued by Roger Bacon, who wrote in his "Opus Majus" of 1268 about experiments with light shining through crystals and water droplets showing the colours of the rainbow. In addition, Bacon was the first to calculate the angular size of the rainbow. He stated that the rainbow summit can not appear higher than 42° above the horizon. Theodoric of Freiberg is known to have given an accurate theoretical explanation of both the primary and secondary rainbows in 1307. He