The Discovery of Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Wikipedia
Surface area: 61.42 billion km²
Radius: 69,911 km
Orbital period: 11.862 yr; 4,332.59 d; 10,475.8 Jovian solar days;
Moment of inertia factor: 0.254 I/MR2 (estimate)
Due to its monstrous size, Jupiter is one of the five planets that can be seen with the naked eye making it difficult to ascertain the authenticity of its discovery. Indeed being easily visible at night, many people must have seen this gigantic celestial body in the sky. The Romans even went on to name it after one of their Gods. While it's difficult to say who discovered it, the most credible theory gives the credit to Italian astronomer, Galileo.
Although Jupiter was seen in the night sky without the use of telescopes or binoculars, Galileo Galilee was the first person to observe the planet more closely with his rudimentary telescope in 1610. As a result of this, many sources accredit Galileo as its discoverer. He also discovered the first four moons of Jupiter, which were named J1, J2, J3, and J4. This was a historic discovery which altered the course of astronomical science to a great extent.
Galileo's observations of Jupiter also led to the end of the age-old myth that the Earth was the center of the solar system, while all the other objects in the sky revolved around it. The model of solar system developed by Nicolaus Copernicus, which stressed on the fact that the Sun is the center of the solar system and other objects revolve around it, got the much-needed support from Galileo's discovery of the Galilean moons.
As technological advancement began, the rudimentary telescopes used by astronomers began to become more sophisticated and hence, more precise. In due course of time, more moons of Jupiter were discovered, thus bringing the total number to an astounding 63. In addition to this, astronomers also noticed a planetary ring system made up of dust around the planet, which was eventually named the Jovian ring system or the rings of Jupiter.
In 1973, approximately 363 years after the discovery of Jupiter, NASA sent the first spacecraft to the planet. Today, we know a lot more about this planet as compared to what we knew in the 17th century when the planet and its moons were newly discovered. The moons of Jupiter are located at an incredible distance from the planet and take a long time to orbit it. The 12th moon, for instance, located at a distance of 14,880,000 miles from the planet, takes two years to orbit it. The gravitational field of Jupiter is so strong that the Shoemaker-Levy 9 Comet, which was anticipated to crash into Jupiter, got disintegrated into 20 fragments as soon as it entered it.
The planets in our solar system have been in existence for millions of years. The fact that Jupiter has been cited in the accounts of various civilizations for centuries, makes the details of its discovery even more difficult to un-earth. Having said that, it's worth noting that there is no dearth of sources which stress on the fact that it was discovered by Galileo.