Follow this link to skip to the main content National Aeronautics and Space Administration Logo
NASA Banner
Mars Exploration Program


THE 1700s (The era of the telescope)

Giancomo Miraldi observes "white spots" at the poles, and discovers that the southern cap is not centered on the rotational pole.

Miraldi wonders (correctly) if the "white spots" are ice caps.

Mars is in opposition, and closer to Earth than it would be until the year 2003. The brightness in the sky causes panic.

Jonathan Swift's Gulliver's Travels described the Martian moons, although this may just be coincidence. "They have likewise discovered two lesser Stars, or Satellites, which revolve around Mars, wherof the innermost is distant from the Center of the Primary planet exactly three of his diameters, and the outermost five; the former revolves in the Space of ten Hours and the latter in Twenty-one and a Half."

Sir William Herschel (1738 - 1822), the British Astronomer Royal, studied Mars with telescopes he built himself. Herschel believed that all the planets were inhabited and that there were even intelligent beings living in a cool area under the surface of the sun.

Sir William Herschel In Herschel's paper, entitled On the remarkable appearances at the polar regions on the planet Mars, the inclination of its axis, the position of its poles, and its spheroidal figure; with a few hints relating to its real diameter and atmosphere., which declares the axial tilt to be 30 degrees. (The actual current value is 25.19 degrees.) Herschel also mistakenly assumed that the dark areas on Mars were oceans, and the lighter regions land. When two faint stars passed very close to Mars with no effect to their brightness, Herschel correctly assumed that Mars had a tenuous atmosphere. He speculated that Martian inhabitants "probably enjoy a situation similar to our own."

Historical Perspective...

Although the telescope was invented in the 1600s, and first used for astronomical purposes by Galileo in 1609, it did not have an astronomical impact until the 1700s. While science in the 1600s was hampered by the Inquisition, scientists in the 1700s enjoyed a much greater degree of freedom. The telescopes of the 1600s were primitive, while those of the following century were much larger and more powerful. Miraldi made his observations with the Campani Telescope in the Paris Observatory.

Newton designed the first reflector to be used in a telescope and presented it to the Royal Society of London in 1672, but the metals used in mirrors at that time could not be polished adequately. In 1722, John Hadley produced a reflector that performed well.

Herschel was a major innovator in the world of telescopes. He found that the long telescopes were difficult to manage and that the reflectors of the day were prohibitively expensive, so he attempted to create his own. After many attempts, he made a working reflector. Eventually, he would create some of the most advanced telescopes of the day, with focal lengths of 2.1-m, 2.7-m, and 6.1-m.

With the increases in telescope quality and availability, scientists of the 1700s paved the way for future Mars research. These telescopes allowed the discovery of the Martian polar ice caps, and many significant features of the Martian terrain. Hundreds of years later, many of the results from the 1700s have been corroborated by experimental evidence.