I am staying at the last level of my block (level 16). i was tending to my plants at 10.50pm on the stated date. it was a very clear and cloudless night when i looked up and saw this boomerang like "cloud" flying by. the "cloud" has a very faint body and it maintained its shape while speeding past. wind direction at this time is towards northeast but i observed it flying directly towards east direction. i estimate it to be about 2km away from where i am looking. it covered the entire distance from left to right in just a mere couple of seconds. there is no light nor sound coming from the object. attached is not the actual picture but a photo of the view which i added the "cloud" to illustrate what i witnessed. the size of the "cloud" illustrated in the picture is exactly the size in relative to the buildings below.