How to Spot a Planet in the Universe

There are an estimated 200 billion trillion stars in a universe that's 93 billion light years in diameter. So how do we know so much about this universe that we couldn't possibly hope to explore ourselves? The simplest tool we have for exploring the universe is the telescope, which we've had for hundreds of years. We're looking at the universe in many different ways, and the furthest back we can pair across the universe some of the oldest and brightest objects and events in the universe.