Introduction 1
Big, Blue, Spinning Ball The Earth 3
What if you dug a hole through the Earth? 4
What if you dropped a rock down a hole through the Earth? 6
What if the Earth were square? 8
What if you lived at the North Pole? 10
What if the Earth had no magnetism? 12
What if the Earth spun very fast? 14
What if the Earth suddenly stopped spinning? 16
What if the Earth were covered by water? 18
It’s Raining Frogs Weather and Climate 21
What if the Earth were hit by a big meteorite? 22
What if a day lasted a year? 24
What if there were no seasons? 26
What if it rained cats and dogs (or fish and frogs)? 28
What if people could control the weather? 30
What if the climate got much hotter? 32
What if the sky were always cloudy? 34
What’s the Matter with Matter? Forces and Energy 36
What if things fell up, not down? 38
What if things could pass through one another? 40
What if water didn’t evaporate? 42
What if drops of water were really big? 44
What if water could flow uphill? 46
Are You Seeing Things? Light and Sound 49
What if everything were the same color? 50
What if the sky were black during the daytime? 52
What if light didn’t travel in straight lines? 54
What if light traveled very slowly? 56
What if you could see sounds? 58
What if you could see in the dark? 60
Into the Wormhole Time 63
What if all past time were squeezed into one year? 64
What if you could travel into the future? 66
What if you could travel into the past? 68
Candle Clocks and Supercomputers Inventions 71
What if cars didn’t need fuel? 72
What if electric lights hadn’t been invented? 74
What if clocks hadn’t been invented? 76
What if computers could think like people? 78
Smart Pigs and Pet Dinosaurs Plants and Animals 80
What if the dinosaurs hadn’t died out? 82
What if we brought the dinosaurs back? 84
What of all plants and animals disappeared? 86
The Amazing, Changing Me People and Animals 89
What if some animals were smarter than people? 90
What if you were size of an insect? 92
What if you were the size of a giant? 94
What if you had a dog’s sense of smell? 96
What if you could fly like a bird? 98
What if you saw the world upside down? 100
What if you had three eyes? 102
What if you looked exactly like everyone else? 104
What if you always knew what other people were thinking? 106
The Superstar and the Big Cheese The Sun and the Moon 109
What if the Sun stopped shining? 110
What if the Sun doesn’t rise tomorrow? 112
What if the Earth didn’t go around the Sun in a circle? 114
What if the Earth had two suns? 116
What if the Moon fell down? 118
What if the Moon were much closer to the Earth? 120
What if there were no Moon? 122
What if you moved to the Moon? 124
Nonstop Flight to Neptune Visiting Other Planets 126
What if you visited Mercury? 128
What if you visited Venus? 130
What if you visited Mars? 132
What if you visited Jupiter? 134
What if you visited Saturn? 136
What if you visited Uranus or Neptune? 138
What if you visited Pluto? 140
What if you visited planets in another solar system? 142
Beam Me Up The Stars and Beyond 145
What if you traveled to the nearest star? 146
What if you traveled to the center of our galaxy? 148
What if you traveled to another galaxy? 150
What if you went to the edge of the universe? 152
What if there are intelligent aliens? 154
What if tiny aliens landed on Earth? 156
What if aliens lived inside the Earth? 158
What if aliens who looked just like us landed on Earth? 160
What if aliens who wanted to talk only dogs landed on Earth? 162
Glossary 165
Index 175
