a dot of white, blur > motion blur horizontal. duplicate this layer and transform it wider and shorter and layer until it has a nice natural look, merge all together. duplicate, rotate 90 degrees, merge. duplicate layer, rotate 45 degrees, transform 60%, center. white blurry dots in the center at increasing size (decrease opacity for each). merge (or dont), light gaus blur, outer glow white
E: had to duplicate and transform the original 'line' 2 or 3 times in varying width and height.
the trick is creating a few original white dots and motion blurring them different amounts and then transforming the results so when you center them all and layer they have a natural feathered look but still are opaque enough.
here's the super lazy result: