By now youve probably seen the new Earth at Night images and videos from NASA. Chris Elvidge, a NOAA scientist who has studied the Earth at night for over 20 years (talk about an awesome job!) says, Nothing tells us more about the spread of humans across the Earth than city lights.

Seen from ~500 miles above the Earths surface, you can see what he is talking about: a sprawling network of humanity stretching inward from coastlines, following rivers, tracing old trade routes, and in some cases ending abruptly at borders (who said there are no borders from space?).

But if we take a slightly closer look, say from 200 miles above the Earths surface, we can see a different level of detail and learn about cities and human expansion, which is what the lucky folks on the International Space Station get to do (another awesome job!).

Ive curated a handful of my favorite nighttime shots of cities and regions from NASAs Earth Observatory, picking cities and regions with large populations in order to highlight the patterns of roads and infrastructure.

These nighttime shots show how humanity has decided to cluster together in cities over time. We do so in sharp lines, rings, and concentrated hot spots of glowing lights. High pressure sodium light pollution acts like a radioactive marker, the orange glow showing us where trade and transportation occurs, where people have settled and how they get to where they need to go, and where water exists. Dark expanses (either water, or rural areas) are a reminder of the relative protection cities offer us from the harshness of the land.

Several things are immediately obvious: cities are designed differently. Some are laid out in orderly grids, while others fan out from hubs of activities at their centers. Others have grown ring roads, expanding outward as outskirts are consumed and absorbed into the city - like concrete trees rings, leaving evidence of previous growth. Depending on the age of a city and the geography, one citys layout can differ a lot from a city of similar size.

Riyadh, Saudi Arabia (NOAA)

Seen during the day, this city of over 5 million people lies in the middle of a desert. Seen during the day, it looks like a smear of gray on the landscape. At night, however, the city practically sprouts up from the desert. It is fairly orderly: major roads are laid out in a grid pattern with a handful of major thoroughfares and ring roads (ah, the rise of the automobile!).

Beijing and Tianjin, China (NOAA)

The United Nations estimates that the general Beijing area has a population around 12 million, while its neighbor Tianjin is in the neighborhood of 7 million. These two cities look like they will consume the (relatively) smaller city of Langfang that sits in between them, turning the area into a megalopolis (if it isnt one already), much like the Dallas-Fort Worth metroplex in the United States. According to NOAA, the surrounding dark areas are farmland.

The Nile River Delta (NOAA)

Water is essential to life, as is evident in the Nile River Delta.

Los Angeles, CA (NOAA)

Over 13 million people inhabit the coastal basin that contains Los Angeles. We can clearly see the borders of surrounding mountain ranges (Santa Monica and San Gabriel Mountains to the north, Chino Hills to the east, and Santa Ana Mountains to the southeast) hemming in the development.

Shipping centers and the LAX airport are also highly visible, as is the grid pattern that stitches together neighborhoods.

Honorable mentions: Chicago, Illinois; Tokyo, Japan; Sao Paulo, Brazil; Seoul, South Korea.