Our planet has existed for 4.54 billion years. Its oceans for roughly 3.8 billion years. And the first life appeared approximately 3.77 billion years ago.There are thought to be more than 8 million species on Earth, and we're still the only planet with life (that we know of!).Readers can explore every facet of Earth in this informative guide to geography for curious kids.From its colossal continents to its vast oceans, and its rocky layers to its atmosphere, what makes Earth unique?How did it get here? And what will become of our planet in the future?