Hello, i'm reading through a book called "Discovering The Universe" and in the chapter about cosmology the familiar idea of the observable universe is discussed. It speaks of the radius of the cosmic particle horizon being ~15 billion light years, which makes perfect sense as light from further away has not had time to reach us yet. But I have a question. Have we ever seen, or are we actively looking for new stars in the night sky? Am I right in thinking as time goes on, it's possible that light from a never before seen star will reach earth and will effectively 'appear' in the sky. Are we likely to notice if one does? Thanks!