Answer:
Step-by-step explanation:
- We take green for granted, but green is an important color. It is nature's sign that sunlight, carbon dioxide and water are being converted into plant food by photosynthesis — the process that provides the basis for animal life. Early in the planet's history, life may have been purple, one theory goes, assuming microbes used some molecule other than chlorophyll. Who knows if purple would have tasted good!
- Earth was formed about 4.54 billion years ago. It took hundreds of millions of years before simple life forms appeared. However, it wasn't until very recently — around 585 million years ago — that any advanced multicellular animal life developed, and these were just tiny sluglike creatures the size of a pill. Humans have walked the surface of Earth for an eye-blink of geologic time — perhaps 4 million years. If our star and our world had shorter life spans — as many do — we'd never have gotten on our own two feet and developed brains big enough to ponder just how lucky we are to be here.
- There's a reason we've found life on Earth and nowhere else. Our world orbits the sun at just the right distance — not too hot, not too cold. This habitable zone is where water can exist in liquid form — a basic requirement for life. Nobody is bragging about their oceanfront property on Mars or the cool breeze on Venus.