To quote the Hitchhiker’s Guide to the Galaxy, “Space is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to space.”
As an illustration, let me present the following image (courtesy NASA).
The picture above is a composite, false-color image, overlaying data from both the Hubble Space Telescope (HST) and a radio image from the Very Large Array (VLA) in New Mexico.
The two reddish jets, invisible to the HST’s visible light camera, are imaged by the VLA. They are composed of hot, high-energy plasma that has been accelerated to near-light speed by a massive black hole that is hidden in the yellow spot at the center of the image. Now this is all pretty amazing by itself, but when you consider the scale of things, it gets even more mind boggling.
The yellow spot that contains the black hole is an entire galaxy. It’s known as Hercules A and contains more stars than the Milky Way. It is over 2 billion light-years distant. Like the Milky Way, it has a black hole at its center, but that black hole, which is responsible for emitting the jets of material, is at least 1000 times more massive than the black hole at the center of our galaxy.
So now, it may be dawning on you that if the yellow spot is something huge, then those jets must be ginormous. They are. The jets stretch for around 1.5 million light-years – roughly the width of 15 Milky Ways spaced end to end. And yet, Hercules A appears as merely one tiny dot in the sky.