The time it takes for light from a star to reach us is also how long ago it existed. So why do scientists talk as if cosmic discoveries happened recently? Senior staff scientist Peter Nugent of the Lawrence Berkeley National Laboratory explains that’s because they’re referring to these events in real time and real time depends on when the events are perceived.

"I’m speaking to you right now and you’re hearing my words in what you think is real time but it’s not. The words left my mouth a few milliseconds before the sound waves make it to your ear. So, for you it’s real time because that’s as soon as you can get it. So, that’s what we’re doing even though these stars could be up to a billion light years away, it’s taken a billion years for that light to reach us, real time for us means well we can study that star every single second as the light reaches us, just meaning as the photons get to us. It’s no different than the fact that you think you’re talking to me in real time. But you’re not. It’s milliseconds after the fact."