Research: Research the topic of Earth and its various components such as space, animals, continents, and nature. Look for interesting facts and stories that would be appropriate for a 4-year-old.

Outline: Create an outline of the book, including the topics you want to cover and the order in which you want to cover them.

Writing: Write the book, using simple language and concepts that a 4-year-old can understand.

Illustrations: Find or create illustrations that will help bring the book to life.

Editing: Have someone else read the book and provide feedback. Make any necessary changes.

Publishing: Publish the book either through a traditional publisher or self-publishing.