That dinosaurs went extinct 65 million years ago is pretty common knowledge. Not as well known, but just as fascinating, is the fact that Earth was on the other side of the galaxy when most of them were alive. It takes the sun (and thus the rest of the solar system) around 250 million years to orbit the center of the Milky Way. The first dinosaurs actually appeared at the dawn of the Triassic Period around 250 million years ago, but for most of their very long reign — namely the Jurassic and Cretaceous periods — our humble planet was in a completely different neighborhood of the galaxy. That means, of course, that the stars the dinosaurs saw in the sky would have looked different from the view we have today.
Though not new information, this knowledge made something of a splash a few years ago when NASA astronomer Dr. Jessie Christiansen created an animation showing which part of the Milky Way our prehistoric predecessors resided in. Perhaps the most intriguing part of the video is its ending, which asks what our planet might be like the next time we complete a trip through the Milky Way. Fortunately, our solar system stays far, far away from the inhospitable galactic center (and its supermassive black hole) as it moves through space. If it didn’t, there’d be no life on Earth whatsoever — human, dinosaur, or otherwise.
Along with the Triceratops and Tyrannosaurus rex, Stegosaurus is one of the world’s most famous dinosaurs. That’s thanks largely to the big, bony plates that lined its back, but there's just one problem: No one knows what purpose they served. Theories abound, ranging from the idea that they protected the creature from other dinos to the possibility that they were a visual display meant to seek mates; some even think they were like prehistoric solar panels that helped regulate body temperature. But there’s no consensus. Their tail spikes — unofficially named “thagomizers” thanks to none other than Far Side cartoonist Gary Larson — were certainly there as weapons, but their keratin-covered plates don’t seem like they would have been very effective in that regard, since it’s not really clear how they would have deployed the stiff, immobile structures. Like much else about dinosaurs, the mystery lingers.