If you don't have a timer, the easiest way to take a self portrait is pop the camera on a tripod and open the shutter for the longest exposure your camera can handle. Then, you move really fast as you get into position and then stand still for the remainder of the exposure.

You'll look a little bit transparent and be surrounded by fainter motion blur from when you were getting into position. I've done exactly this on moonlit nights, and the result looks completely consistent with the photo in the article. You also get ghostly duplicates if you hesitate as you get into position.

Could the shutter speed was an accident and the subject happened to pause enough to show up visibly on the image- much like the first photographed human, who was getting his shoe shined: http://mashable.com/2014/11/05/first-photograph-of-a-human/

If it's not a selfie, it's an extraordinarily lucky accident that there's a recognizable human in the photo.

ed: it's possible it was just really dark, and all the photos were exposed for that long. Someone wanted a picture of Korneyev, and he moved during the exposure. But the combination of "blurry person" and "crisp person" makes me lean towards the selfie hypothesis. Someone trying and failing to stand still won't wave a flashlight around. Someone rushing to get into a selfie shot might.