Giovanni Batista Hodierna was a 17th-century Italian astronomer and mathematician, born in 1597 in Palermo, Sicily. He is best known for his work in telescopic astronomy and for his contributions to the understanding of celestial bodies. Hodierna designed and built telescopes, which allowed him to make significant observations of the moon and planets. In 1654, he published a book titled De Systemate Mundi, where he presented his theories on the structure of the universe. Hodierna's work laid the groundwork for future astronomers and helped advance the field of observational astronomy during a time of great scientific discovery.