White semi-transparent oval-ish object moving at high speed directly opposite direction of airliner.Friday, May 16, 2014 I was outside in my backyard in Calgary, Alberta, about 5:15pm and noticed that airliners coming out of YYC airport appeared to reaching higher altitudes faster than what we normally see in take off patterns.I watched one airliner as it banked from its southward climb out to a westward direction.Approximately one minute later, I noticed another airliner which remained climbing out in a southward direction and appeared to be at a surprisingly high altitude for just coming out of our airport.As I watched that airliner move past the directly vertical position my eye caught an object moving in exactly the opposite direction, south to north, at what appeared to be a high altitude at a speed at least equal to the airliner. The object was white in colour, with a bit of an oval shape about it and with a degree of transparency towards the middle. It appeared smaller than the airliner and I at first thought that it must be a bird but there were no wings and none of the typical motion of a bird. The flight path was very straight.It was in my field of view for approximately 10 seconds and having ruled out it being a bird I wondered if it might perhaps be a balloon being pushed along by a high altitude wind even though there was no wind at ground level and when I have seen weather balloons or kids balloons in the past they have all displayed some degree of buffeting motion being pushed along by wind. In this case the object had a solid trajectory as it travelled along. No sound from object.