Large triangular-shaped object travelling East to West at approx.Mach 1-1.5 over North Memphis, TenneseeI have been a commercial pilot since 2001. I have studied aircraft since the age of 4. I have seen many strange things in the air, but nothing compared to this. At approx.2139 hrs on 24 Nov 2009, I was watching departing air traffic from MEM pass overhead looking North. Something caught my eye to the East. I turned, and saw a Triangle-shaped object that had large dull white lights at all corners. It was either in a right-hand bank turning North, or it was flying due West at a tilt because I could see the bottom of the object while it was apparently miles to the North of me. It traveled at approx. Mach 1-1.5. It was completetly silent. That impacted me quite a bit because being a glider pilot as well, I know that even a glider at higher speeds causes a lot of noise through aerodynamic means as air is "split" around the aircraft. The object passed below a departing CRJ-200 from MEM. I would love to know if anything was picked up on the aircraft's TCAS, or by MEM Center. I have the urge to call them, but fear the backlash that may follow. It was approximately 200 ft across to all corners. It had a dull grey looking surface, and as I said earlier the 3 large white lights were dull. I don't drink, or use drugs. I have had an FAA pilot's license for over 20 years, and been with the airlines since 2001...I still feel stunned, even though it's been over 12 hrs ago.