Astronaut Karen L. Nyberg even got caught up with the images she took in late summer but hadn’t had a chance to post on Twitter before.
Such is the case of the photo to the right of the North American Great Lakes.
It was taken on August 23, 2013, and shows four of the five Great Lakes, revealing approximately one fifth of the world’s fresh water in a single photo.
The oblique angle of the image highlights the unique perspective astronauts orbiting aboard the International Space Station (ISS) are treated to, which is quite different from looking at a map or even at a globe.
The ISS orbits at an inclination of 51.65 degrees, meaning that while it does pass over some middle latitudes of the northern and southern hemispheres, it never goes into the Arctic or Antarctic, or directly over the poles.
And its average altitude of 259 miles above sea level allows for only a limited view of the planet below at any given time. That’s why the image of the Great Lakes somewhat appears to have been taken with a fisheye lens when it was actually taken with a 50mm wide-angle lens.
The position of the ISS at the time the August 23 image was taken caused the sun to reflect off the surface of Lake Ontario like a mirror. To a lesser degree, the “sunglint” illuminated Lake Erie and the Niagara River connecting Lake Erie and Lake Ontario, as well as a lesser-known stretch of water just to the west.
Niagara Falls and other obstacles prevent vessels from being able to navigate the Niagara River to get between the two lakes it connects. So engineers in the 1820s constructed a ship canal that has since been expanded to now allow nearly 40 million tons of cargo to be carried through it annually.
The 26-mile-long Welland Canal can be faintly seen just to the west of the much brighter Niagara River in the far right of the image. Its eight locks allow ships to rise or fall the 326-foot difference between the two Great Lakes the canal connects.
Image: Karen L. Nyberg NASA