What does the illustration of Earth resemble, as described in the provided text?

The illustration of Earth, described as resembling a doughnut hole with radiation belts, captures the unique structure of the planet's magnetic field and its interaction with solar radiation. This imagery highlights how Earth is not only spherical but also surrounded by protective radiation belts known as the Van Allen belts, which are shaped in a manner similar to the hole of a doughnut. This protective feature is crucial because it helps shield the planet from harmful solar and cosmic radiation, thus maintaining conditions suitable for life.

The concept of a doughnut hole serves to simplify the understanding of Earth's magnetic field and its layers, allowing for a visual representation that illustrates the way in which these radiation belts encircle the planet rather than simply surrounding it in a traditional sense, as a sphere might. This unique relationship between Earth and its radiation environment is an important aspect of planetary science and the understanding of how our planet is safeguarded against space weather phenomena.