An astronaut above the International Space Station has captured a stunning image of what NASA refers to as "one of the few places on Earth where an international boundary can be seen at night." The Sept. 23 image shows the glowing, snaking border between India and Pakistan, visible because of the Indian floodlights that dot much of the way. The Wall Street Journal notes two other such borders: the boundary lines between the Koreas and between South Africa and Zimbabwe. In those cases, a dearth of electric lights on one side makes clear the difference. The India and Pakistan boundary is visible because of lights that wind their way through nearly 1,200 miles (the full border is about 2,000 miles long). Their intended purpose is to discourage militants from crossing from Pakistan into the part of Kashmir controlled by India, per the Journal.
The Economic Times in March reported that due to the huge cost of lighting the border—owing to the electricity used and the diesel generators stationed there as back-up—the country intends to replace the floodlights with LED bulbs in the coming years. A pilot program along the border in Punjab will test out the LED bulbs, which can have 50 times the lifespan of regular ones. A neat note from NASA regarding distances, time, and progress: It points out that in 327 BC Alexander the Great traveled through the Indus River valley, which is identified in the image. He entered from the northwest and exited near Karachi, at which point he headed back to what is now Iraq. The journey took him "many months"; the ISS covers the same distance in three minutes. (See an incredible picture of the moon that NASA recently captured.)