Which event in 1572 challenged the belief that the heavens were unchanging?

• A. The discovery of Pluto.
• B. The observation of a new star, the supernova.
• C. Galileo's Venus phases.
• D. Kepler's laws.

Answer: (B)

The main idea tested is that the heavens could be dynamic, not perfectly unchanging. In 1572 a bright new star appeared in the sky and was carefully observed by Tycho Brahe. If the heavens were truly immutable and composed only of the fixed stars, a new celestial object should not suddenly appear among them. The appearance of this nova showed that changes could occur in the sky itself, challenging the long-held view of a static, flawless celestial realm and helping push astronomy toward a more modern, dynamic understanding of the cosmos. The other historical events fit within evolving models of the universe but do not demonstrate a new celestial object appearing in the heavens, which is what directly unsettled the idea of heavenly immutability.