That's an easy one. What you were looking at was the sun-shaped launchpad of the ill-fated and now defunct Cloud Nine helium balloon attraction, which used to offer tethered rides from a site located opposite Mandalay Bay, until damage from successive high winds led the owners to give it up. You can see the solar design in the Google map and photograph below; plus, click this link for a great birds-eye view taken by someone during the ride, which clearly shows the rays of the sun radiating out.
This site, which is located at the corner of Hacienda Ave. and the Strip, is now slated to house part of the Skyvue attraction, the rival observation-wheel and adventure-park project vying with Caesars Enterainment's center-Strip Linq, both of which have won approval from Clark County Commissioners, although it's considered unlikely that Las Vegas could support two giant Ferris wheels.
