It appears to be in the front of the tree's branches, because the part of the branch that is covered by that "object" is brighter. Also note that very bright street-light at the lower right. So it could be either some dust on the lest, some residue from an evaporated water-drop, or simply a reflection in the lens, caused by that street light.
Since it really appears to be in front of the branches, it is definitely nothing "up in the skies".
Just cropped the image to the interesting part, scaled it x2 and made two versions of it.
The original is, well, the original, just scaled.
In the adjusted one i selected the spot (circular selection) and simply reduced the brightness-curve of that selection. As you can see the branch now has almost the same color as in the outside of that region. So, whatever it is, it is in front of the tree/branch, and not in the sky.