I’ll make this short and (bitter)sweet: There’s a picture going around social media people claim shows Antarctica from space.
But it’s not; at least not really. It’s actually a visualization of data, a computer-generated image showing the extent of sea ice around Antarctica on Sept. 21, 2005.
The overall image is a composite from several different Earth-observing satellites, but the sea ice is from the AMSR-E detector on board the Aqua satellite. It uses microwaves to measure the extent of ice floating in the ocean. This was then mapped onto a computer-generated globe of the Earth from Blue Marble Next Generation (using different data from AMSR-E to estimate the ice color). The terrain map is actually from 2004, a year before the ice data were taken.
Perhaps it’s a subtle point. After all, many images from Hubble and other observatories are composites using separate images, sometimes in wavelengths invisible to our eyes! While this case is similar, it isn’t a snapshot taken by some orbiting camera; it’s more like making a map (like ones showing color-coded temperatures) created using various sources and then putting them together in a way that looks very photorealistic.
It's certainly beautiful, and even helpful both scientifically and with getting people to see our planet in a different light. But it's not really a photo of Earth from space.
Perhaps too it’s not a big deal. It’s not a fake, or a hoax, or anything like that. But I do think it’s a good idea to understand the difference between an actual photo and a visualization. Under the assumption they’re real, unreal pictures are commonly passed around social media rapidly and without much critical analysis. I see this a lot (at the bottom of this article is a short list of just a few such widely shared pictures I’ve written about), and I think it’s worth pointing out the difference between the real and the imagined.
I’m not trying to pick on people who do this, either. It’s natural to want to share something beautiful or exciting or awe-inspiring! And I’m glad people do, because images from and of space are beautiful and should inspire us.
But in my opinion, the real Universe is amazing enough without having to make stuff up about it. It’s important to be able to tell the difference between a photo depicting reality and a drawing meant to represent it, and something I wish more people could do.
More articles about fake/hoaxed pictures or illustrations mistaken for reality: