According to Galileo's prompt, Dominique Cassini carefully observed the operation of Jupiter's satellite and compiled the ephemeris of the world's first Jupiter satellite, which completely solved the problem of accurately determining the longitude position when sailing at sea. Dominique Cassini's most important contribution is his observation of Saturn. He not only observed and studied Saturn's moons, but also studied Saturn's beautiful rings. In order to study the mystery of Saturn's ring formation, he made a long and careful observation of Saturn. He first discovered that Saturn's rings were divided into two concentric circles by a gap. Therefore, until today, people still call the gap in the middle of this mysterious aura "Cassini seam". Later, Cassini finally came to the correct conclusion through many observations: "Saturn's aura is composed of countless small satellites."
Dominique Cassini's work was not confined to Italy, and his outstanding contribution to astronomy quickly attracted the attention of the world scientific community. 1669, the French Academy of Sciences established the famous Paris Observatory, and Louis XIV immediately invited Cassini to France to preside over the work of the Observatory. At the Paris Observatory, Cassini ordered a large telescope for astronomical observation, and made a more serious study of the sun, moon and other planets under good working conditions. In his observation of Mars, he found the white "polar cap" of Mars and compared it with the two poles of the earth. 1672, Cassini also participated in and presided over the joint observation of Mars, and then he deduced the real distance between the earth and Mars according to the observation results.
Another important contribution of Dominique Cassini is that under his prompt and guidance, his assistant Ramo of Denmark completed the first measurement of the speed of light. In the past, many people thought that the speed of light was infinite. According to the Jupiter satellite table made by Dominico Cassini, Remo took advantage of the "star eclipse" of Jupiter satellite to measure the time required for light to reach the Earth from Jupiter. 1676165438+1On October 22nd, Remo reported his observation that it takes about 22 minutes for light to pass through the earth's orbit (the result of modern scientific determination is16 minutes and 36 seconds). Although the error of this value is relatively large, it is the first time that human beings have measured the speed of light, but its significance is quite far-reaching.
In Italy, although Torricelli, Dominique Cassini and other outstanding scientists inherited Galileo's career, Italy, which once had a large number of talents, gradually declined due to the destruction and persecution of science and scientists by religion, and the center of science also shifted from the Mediterranean coast to other parts of the European continent.