With reference to the visibility of planets and stars during total eclipses of the sun; in the eclipse of May 12, 1706, Venus, Mercury, and Aldebaran, and several other stars were seen. During the totality of the eclipse of May 3, 1715, about twenty stars were seen with the naked eye.[482] At the eclipse of May 22, 1724, Venus and Mercury, and a few fixed stars were seen.[483] The corona was also noticed. At the eclipse of May 2, 1733, Jupiter, the stars of the "Plough," Capella, and other stars were visible to the naked eye; and the corona was again seen.[483] During the total eclipses of February 9, 1766, June 24, 1778, and June 16, 1806, the corona was again noticed. But its true character was then unknown. At the eclipse of July 8, 1842, it was noticed by observers at Lipesk that the stars Aldebaran and Betelgeuse (α Orionis), which are usually red, "appeared quite white."[484] There will be seven eclipses in the years 1917, 1935, and 1985. In the year 1935 there will be five eclipses of the sun, a rare event; and in 1985 there will be three total eclipses of the moon, a most unusual occurrence.[485] Among the ancient Hindoos, the common people believed that eclipses were caused by the interposition of a monstrous demon called Raha. This absurd idea, and others equally ridiculous, were based on declarations in their sacred books, and no pious Hindoo would think of denying it. The following cases of darkenings of the sun are given by Humboldt:-- According to Plutarch the sun remained pale for a whole year at the death of Julius Cæsar, and gave less than its usual heat.[486] A sun-darkening lasting for two hours is recorded on August 22, 358 A.D., before the great earthquake of Nicomedia. In 360 A.D. there was a sun-darkening from early morn till noon. The description given by the historians of the time corresponds to an eclipse of the sun, but the duration of the obscurity is inexplicable. In 409 A.D., when Alaric lay siege to Rome, "there was so great a darkness that the stars were seen by day." In 536 A.D. the sun is said to have been darkened for a year and two months! In 626 A.D., according to Abul Farag, half the sun's disc was darkened for eight months! In 934 A.D. the sun lost its brightness for two months in Portugal. In 1090 A.D. the sun was darkened for three hours. In 1096, sun-spots were seen with the naked eye on March 3. In 1206 A.D. on the last day of February, "there was complete darkness for six hours, turning the day into night." This seems to have occurred in Spain. In 1241 the sun was so darkened that stars could be seen at 3 p.m. on Michaelmas day. This happened in Vienna.[487] The sun is said to have been so darkened in the year 1547 A.D. for three days that stars were visible at midday. This occurred about the time of the battle of Mühlbergh.[488]