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This Week in Astronomy History: June 7-13

Photo: A painting of Pioneer 10’s flyby of Jupiter | Rick Guidice

A portrait of Giovanni Cassini | Wikimedia Commons

June 8, 1625: Giovanni Cassini born

Italian astronomer Giovanni Cassini was born in the municipality of Perinaldo (located in the Liguria region of modern Italy) on June 8, 1625. Cassini is best known for his work in the fields of astronomy and engineering, discovering four moons of the planet Saturn as well as divisions in its rings. This introduced the idea that Saturn had not one large ring, but multiple smaller rings with gaps in between them. The Cassini Division, a region between two of Saturn’s largest rings, is named after him. Another well-known namesake of his is the Cassini space probe. Launched in 1997, it was the fourth probe to visit the ringed planet and the first to orbit it.

June 13, 1983: Pioneer 10 leaves the proximity of major planets in the Solar System

An artist’s impression of Pioneer 10 looking back on the inner Solar while on its way to interstellar space | NASA/Don Davis

Pioneer 10 was a space probe launched by NASA on March 2, 1972, with the intention of exploring the outer solar system. Shortly after launching, it became the first spacecraft to travel through the asteroid belt. From there, it photographed Jupiter, transmitting over 500 images back to Earth. Over the course of its mission, it gathered new information about the asteroid belt, the environment surrounding Jupiter, solar wind, cosmic rays, and eventually, the furthest reaches of our Solar System.

On June 13, 1983, the craft crossed the orbit of Neptune, making it the first Earth object to travel out of the proximity of the major planets of the Solar System. Though its mission technically ended on March 31, 1997, when it had reached a distance of 67 AU from the Sun, communication with Pioneer 10 continued until its radio lost electric power on January 23, 2003.