Space dust

So how big must the constituent particles of this cloud appearing nebula be? The clouds of earth appear as white bloches on the earth from the moon.  This is a picture of something light years away and yet you can see what appears to be wisps of a cloud or even the dust surrounding it.  In order for the smallest particle to either reflect enough light or block out enough light to register on the mirrors of the hubble telescope I would assume that it would have to be much larger than Saturn by a sizable amount because supposedly planets can not be seen only calculated.  So how big must the particles of this cloud be in order for us to see and assume that it is a cloud ensrouded by dust?

Either things are very big and very strange or this is not as far away as we are led to believe.

I undersand that this is a false color but is it a false representation as well?