The sun is shining for 2 weeks at a time. The flag stays put. You can walk around it and compose nice shots with spacecraft behind or the earth above. You can arrange the drape or move the crossbar to catch the sun's unhindered rays shining along its wrinkles. Other astronauts beside Schmitt and Cernan managed the trick; you can see a fine example from Apollo 11 here and here, while the crew of Apollo 16 also got a pretty good pair.

On earth, you take what you're given.

I first tried the standard approach--Googling for pictures of "flags in front of glass buildings." I had in mind something like a cool picture of those national flags in front of the UN Building. Something big and high-res. Something I couldn't find on my Google. Nothing for it but to once again get out my camera and do the job myself. Here's the procedure if you wish to replicate it. (If you are luckier or smarter than I, you can safely omit Steps 5, 7, 10, 14 to 24, and 26.)

Step 1: Wait for a sunny day.

Step 2: Wait for a sunny, breezy day.

Step 3: Wait for a sunny, breezy day with the breeze blowing in the same direction as the sun's rays so that you can get shadows along the face of the flag.

Step 4: Look for a flag that is on a pole low enough to be photographed face-on within a reasonable distance AND is located in front of a building that has a reflective glass wall unbroken by sashes or sharp angles AND offers a clear line of sight that permits a combined view of both the flag and its reflection.

Step 5: Settle for an arrangement like the one in this picture.

Step 6: Find a vantage point that is high enough to see both flag and reflection, and close enough to photograph fine details.

Step 7: Step 6 is impossible, so use a telephoto lens.

Step 8: You don't have NASA's budget, so set your camera resolution to Maximum Size and compression to Superfine.

Step 9: Set your shutter mode to Continuous Shooting.

Step 10: If you don't understand those last three steps, then buy a disposable camera and repeat Steps 1 through 6.

Step 11: Aim your camera squarely on the flag and its reflection.

Step 12: Wait until the intermittent breeze has stretched out the flag to a billowy and heart-swelling display of national pride.

Step 13: Hold down the shutter button and fire away!

Step 14: Take 15 high-quality and perfectly-framed images of the flag twisted around the pole like the stripes of a candy cane when the wind suddenly shifted six different ways and then stopped with a clang.

Step 15: Watch the wind whip the flag out to a gorgeously shadow-dappled rectangle while you wait for the camera to write 45 megabytes of worthless images to your flash card.

Step 16: Go to Step 13.

Step 17: Find a better, higher vantage point.

Step 18: Tell the security guard you're doing an art project.

Step 19: Tell the panhandler that all your spare change is spent on your art.

Step 20: Take more pictures.

Step 21: Discover that overhead wires are blocking the view of the flag, so climb to an even higher vantage point.

Step 22: Discover that the flagpole is blocking your view of the flag's reflection, so take two steps to the right.

Step 23: Discover that your vantage point was only one step wide.

Step 24: Delete those pictures of the receding sky.

Step 25: Go home, download your pictures, and see your results on the big screen.

Step 26: Go to Step 1.

There are even easier ways to produce the double-positive illusion, and they are described on another page. But with a little determination, a little more luck, and a lot of help from a high-speed camera, it is quite possible to see a flag billow outward on both sides. I'm sure Mary Bennett and David Percy will be happy to hear that.