History of the telescope received the report in November, and the English mathematician and astronomer Thomas Harriot, who used a six-powered telescope by the summer of 1609 to observe features on the moon. The Italian polymath Galileo Galilei was in Venice in June 1609 and there heard of the "Dutch perspective glass" by means of which distant objects appeared nearer and larger. Galileo states that he solved the problem of the construction of a telescope the first night after his return to Padua from Venice and made his first telescope the next day by fitting a convex lens in one extremity of a leaden
Optical telescope 550 nm wavelength, is given by: formula_12 The unit used in the object diameter results in the smallest resolvable features at that unit. In the above example they are approximated in kilometers resulting in the smallest resolvable Moon craters being 3.22 km in diameter. The Hubble Space Telescope has a primary mirror aperture of 2400 mm that provides a surface resolvability of Moon craters being 174.9 meters in diameter, or sunspots of 7365.2 km in diameter. Ignoring blurring of the image by turbulence in the atmosphere (atmospheric seeing) and optical imperfections of the telescope, the angular resolution of an optical