Living on Mars

Living on Mars — page 1
Chapter 1 A SECOND HOME IN SPACE Earth is our home planet It formed from the dust in the solar nebula around 4 5 billion years ago Although life on Earth began as microbes very quickly after the birth of our planet human beings did not appear until three million years ago Like all other organisms on Earth humans have evolved to suit Earth’s environment Our eyes are adapted to see in full sunlight Our lungs work perfectly with Earth’s atmosphere at sea level and our skeletons are designed to cope with Earth’s gravity Our Dangerous World Although Earth is the only place we know of that has life it is also a dangerous place Just think of the extinction of the dinosaurs 65 million years ago We know an asteroid around 6 2 miles 10 km wide hit Earth at this time and massive volcanic eruptions also affected Earth’s climate The asteroid punched a hole in Earth’s surface 112 miles 180 km wide but this crater was discovered only in the 1990s It was not just the dinosaurs that suffered around three-quarters of all plant and animal species became extinct 4