CHICAGO — Lookin' good, Chicago.

NASA has a number of photos of our fair city posted on its website, some taken from the International Space Station some 250 miles above the earth.

They look amazing, but there is a scientific point for making the pictures, the agency said: "Photographs record how the planet is changing over time, from human-caused changes like urban growth and reservoir construction, to natural dynamic events such as hurricanes, floods and volcanic eruptions."

NASA says astronauts have used cameras to photograph the earth for more than 40 years, beginning with the Mercury missions in the early 1960s.

Here are a few:

This one (above) was posted earlier this month in what has been described as NASA's "Black Marble" series. It uses its Visible Infrared Imaging Radiometer Suite on a satellite to remove natural sources of light to measure "patterns of human settlements across our planet."

This was shot by Expedition 47 Commander Tim Kopra of NASA on April 5, 2016. He posted it on social media using the hashtags #Goodnight #Chicago and #CitiesFromSpace"



European Space Agency astronaut Samantha Cristoforetti took this photograph and posted it on social media on Feb. 19, 2015. She wrote, "How do you like #Chicago dressed for winter?"



This simulated-color scene was taken on Sept. 14, 2001.

Patches of green forest can be seen versus the gray and white of roads and buildings in the metro area in this photo from September 2010. Light colored silt and sediment swirl in the dark blue Lake Michigan waters. Between 1970 and 1990 developed land in the Chicago area increased by 49 percent though the population increased by only 4 percent.

Clouds and fog can be seen over Chicago in this February 2012 image. The faint line on the horizon is caused by ultraviolet radiation stirring up the gas molecules in the upper atmosphere, NASA said.

In this 2003 photo, giant ice islands can be seen floating in Lake Michigan. "Note the wind-driven lake-effect snow cover over the western half of the lower Michigan Peninsula," NASA said.

This was taken from the International Space Station in 2014. "The Loop is distinctly darker when viewed from orbit because high-rise buildings cast much more shadow than low buildings in the surrounding neighborhoods," NASA said.