From Cassini to Magellan: Unveiling the Topography of Venus

By neub9
3 Min Read

Venus, a brilliant planet in our night sky, has captivated observers throughout history, receiving various names from ancient astronomers. The maps of Venus featured in this post date back from the 1700s to the early 1990s and are based on observations by Giovanni Domenico Cassini, an influential astronomer and topographer of the 17th century. The first illustration above is an image of Venus derived from Cassini’s observations, included in an atlas published by Nicolas de Fer in 1754. Below are maps of Venus, Jupiter, and Mars also prepared based on Cassini’s work, included in an atlas published by John Seller in the 1700s.

The transit of Venus occurs when the planet aligns between Earth and the sun. The first recorded observation of this phenomenon was made in 1639, an event illustrated in a map included in Richard A. Proctor’s 1875 book “Transits of Venus.” Throughout the 1800s and early 1900s, astronomers developed and proposed various theories about the atmosphere and surface of Venus, leading to the diagrams featured below, from C. E. Housden’s 1915 book “Is Venus Inhabited?”.

In 1961, scientists used Earth-based radar to observe Venus. This marked the beginning of successful missions to Venus by space programs from the United States, the Soviet Union, Japan, and the European Space Agency. One of the most notable missions was the Magellan orbiter launched by NASA in May 1989, with the mission of mapping the entire surface of Venus, covering 98% of the planet’s surface over six mapping cycles. The mission’s planning chart and transparent overlay are shown below. Besides, topographic maps of Venus produced by the United States Geological Survey in the early 1990s using radar imagery are also featured, revealing details about the planet’s topography and landmarks named after famous figures like Ishtar, Aphrodite, Lakshmi, and James Clerk Maxwell.

Discover more about Venus and its fascinating features by watching the following videos sponsored by the Library of Congress’ Science, Technology, and Business Division: “Venus: the Forgotten, Mysterious Planet” by Dr. Lori Glaze from NASA, and “The Transit of Venus” by Dr. Sten Odenwald, also from NASA.

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