After Hours

Geek Trivia: Worth a thousand worlds

What's "wrong" with common displays of the famous Apollo 17 Blue Marble photo?

Gather 'round, space enthusiasts, environmentalists, and photographers all, for we're celebrating the 33rd birthday of NASA archive item AS17-148-22727. Never heard of it? Here are a few clues: AS17 means Apollo 17, 148 indicates roll 148, and 22727 signifies frame 22,727. Still got the what-are-you-talking-about-Trivia-boy look on your face? OK, last hint: The Blue Marble.

That's right—we're talking about the last full-color, full-frame picture of Earth taken by a human being, otherwise known as the Blue Marble photo. Taken mere hours after launch by the crew of Apollo 17 on Dec. 7, 1972, the Blue Marble was the first clear, color image of the entire illuminated face of the earth.

A member of the Apollo crew took the famous shot using a handheld Hasselblad camera. Exactly who took it, no one can say, as all three astronauts took turns snapping pics throughout the Apollo 17 mission. Astronaut Harrison Schmitt often asserts authorship of the photo, but there is no means to verify his claim.

Though satellites have been taking images of the earth—in one form or another—since the 1950s, it wasn't until the translunar Apollo missions that modern color photographic equipment was in the hands of human photographers at a sufficient distance from earth to capture the whole lighted face of the planet in a single shot. So stirring was the image that many environmental and political groups have used it over the years to illustrate the fragility of the planet, subsequently making the Blue Marble one of the most recognized and widely reproduced photographs of all time.

It also didn't hurt that Apollo 17 was the last manned moon mission, so there hasn't exactly been a load of competition for a better whole-earth photo in the last 30 years. While conventional satellites and space probes have produced component images, digitally combined to create a "complete" image of the earth, there hasn't been a "true" whole-earth photo of comparable quality to the Blue Marble—either before Apollo 17 or since.

Ironically, despite its fame and its formal distinction, most displays of the Blue Marble photograph aren't true to the actual photo—and we're not just talking about cropping the frame and boosting the color. A very basic fact about the original Blue Marble photo often goes unacknowledged in reproductions of the picture.


What's technically "wrong" with most reproductions of the famous Blue Marble photo of the earth, originally taken by the crew of the Apollo 17 lunar mission?

Simply put: Most people are looking at the Blue Marble photo upside down. The trajectory of the Apollo 17 spacecraft meant that the flight deck of the Command Module was oriented with the south pole of earth facing up. So, strictly speaking, any displays of the Blue Marble photograph with Antarctica at the bottom of the frame are technically incorrect.

That said, it took an explicit confluence of circumstances to make the original Blue Marble photo possible, not the least of which were the timing and position of Apollo 17's trajectory. Apollo 17 launched from Cape Kennedy in the wee hours of the morning, 12:33 A.M. EST, on Dec. 7, 1972. That schedule allowed the spacecraft to break parking orbit at about 3:51 A.M. EST, sending Apollo away from Earth along its scheduled course above southern Africa and Antarctica during that region's daylight hours.

A member of Apollo 17's crew took the Blue Marble photograph at 5:39 A.M. EST, with the sun lighting the whole perspective face of the earth. (The day/night terminator was not in the frame.) As to what is specifically visible in the frame, here's the original NASA caption of the photo:


The caption makes no mention of the original orientation of the photograph—indeed, reorienting photographs for more intuitive display is hardly uncommon practice—but such are the makings of some highly focused Geek Trivia.

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The Quibble of the Week


This week's quibble comes from the November 23 edition of Geek Trivia, "Early bird special." TechRepublic member J. D. S. busted me for improper use of the term balance sheet.

"Although not an accountant by trade, I once supported accounting (computer) systems, and took a fair share of classes. Although you have the concept correct, rather than balance sheet, it would be better to say income statement or profit/loss statement.

"A balance sheet is always balanced: assets = liabilities + owners' equity. An income or P/L statement shows: revenues - expenses = profit (or loss)."

This is why my wife does the household finances, boys and girls. Thanks for the lingo correction, and keep those quibbles coming.

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