His name is Armstrong. He has pulled a sled for over 25,000 miles and has been at work twice longer than most other dogs, almost 10 years. Curious how far 25,000 miles is? It’s a distance longer than a lap around Earth’s equator. Dogs are amazing creatures, truly, amazing. If you’re as curious as we are about this amazing dog, then you’ll want to make sure that you read the National Geographic feature called “The Cold Patrol” about sled dogs in Greenland.