Christiaan Huygens, Lord of Zuilichem, was a Dutch mathematician, physicist, astronomer and inventor. He is regarded as one of the greatest scientists of all time and a major figure in the scientific revolution. In physics, he made groundbreaking contributions in optics and mechanics, while as an astronomer he is chiefly known for his studies of the rings of Saturn. As an inventor, he improved the design of telescopes and invented the pendulum clock, a breakthrough in timekeeping.