The image of the 1, 200ft-symbol is clearly seen on Google Earth, but has baffled scientists as to what could have made it.
Conspiracy theorists have unsurprisingly decided that the symbol is connected to devil worship, paganism or religious sects.
Situated on the southern shore of the Upper Tobol reservoir, the nearest city â€“ Lisakovsk â€“ is 12 miles away.
The pentagram is an ancient symbol used by many cultures and religious groups, including Christians, Freemasons, followers of the Chinese religion of Taoism, and ancient Mesapotamians.
One internet user, Kurt Yates, from Seattle, Washington, claimed that the symbol was probably an abandoned surface to air missile site.
"I was a military pilot and these things are all over the place in areas that use(d) Russian (Soviet) air defence systems, " he wrote on the LiveScience website.
"The shape has something to do with how their tracking radars work.
"Considering the size of it and the proximity to the Baikonur Cosmodrome, I'd say it possibly was used for tracking Soyuz rockets or some such."
However, Emma Usmanova, an archaeologist who has studied the ruins in the Lisakovsk region, believes she has cracked the puzzle.
"It is the outline of a park made in the form of a star, " she .
"The star was a popular symbol during the Soviet era â€“ Kazakhstan was a part of the former Soviet Union until its dissolution in 1991. Stars were often used throughout the Soviet Union to decorate building facades, flags and monuments.