Kepler encouraged Zucchi’s interest in astronomy. Zucchi maintained correspondence with Kepler after returning to Rome. At one point when Kepler was in financial difficulties, Zucchi, at the urging of the Jesuit scientist Father Paul Guldin, gave a telescope of his own design to Kepler, who mentioned the gift in his book “The Dream”.
Zucchi along with fellow Jesuit Daniello Bartoli may have been the first to see the belts on the planet Jupiter on May 17, 1630, and Zucchi reported spots on Mars in 1640. The crater Zucchius on the Moon is named in Niccolò Zucchi's honor. Bartoli wrote his Jesuit biography (1682).