I was at work photographing some flowering trees. the weather was generally sunny with occasional low clouds crossing the sun. i was waiting for a mass of clouds to pass so that bright sun would return so i could take photos. i looked up to where the sun was behind the clouds. at that moment i noticed a vey fast moving aircraft. it was white colored and flying well above the cloud level. it appeared to resemble a concord jet but with sleeker wings and no tail, just a blended body. i saw it for 10 seconds at the most. i turned my camera back on but by that time it had flown behind the cloud bank. since it was flying very rapidly and in a straight line i got my camera ready to photograph it once it came by the other side. but it never appeared. i heard no noise and saw no contrails. it was traveling from southeast to northwest.Where i was is in the flight path for jets landing at orlando international airport which is appx 10 miles south of the sighting location. they are usually low enough where often you can make out the airline name or logo on the jet. i also see jet traffic flying over at higher altitudes. this unknown aircraft seemed to be flying higher than commercial jets. i did not notice any lighting or any markings or insigna. just a white colored aircraft. from my vantage point the size in the sky was very small, maybe aspirin size from an outstretched hand. afterwards i watched and scanned around for about 5 minutes and saw nothing. i have attached a rough sketch i made of what i saw.