Magnetism on Earth is primarily due to its molten iron core, which generates a magnetic field that extends into space. This magnetic field protects the planet from solar radiation and helps in navigation for various species, including humans. The discussion highlights the importance of understanding Earth's magnetism for applications in technology, such as compasses and GPS systems. Additionally, it emphasizes the need for clarity in questions regarding the topic to facilitate better discussions. Overall, the effects and applications of Earth's magnetism are crucial for both natural phenomena and human advancements.