The Imagination That Astronomy Reveals

For those of us who study this hobby called amateur astronomy, I think sometimes we forget some things that are right in front of us. Or perhaps we just never quite understand them. They really deserve to sit beside each other in an article to evoke those ideas though. Let’s begin

When you look out at the night sky, night after night, season after season, year after year, you don’t see chaos. What you see is predictability, a sense of calm, of relaxation, of time spent with an old friend. Maybe you just casually like to point your telescope at a galaxy, or a globular cluster, and just enjoy the image, or for some, the visual of it all. All of that is fine.

When you are looking out at the night sky, you are on a time delay. You are looking at light from the past, whether it is a few seconds ago or a few billion years ago. None of it is in real time. When we are looking at galaxies from the local group, we are talking a few million light years distant, or the local supercluster, say 30 million years distant, or even a few distant superclusters. All of it is old news. The galaxy shown in the picture was taken last night, as it appeared 30 million years ago.

Now we should talk about the distance problem. The fastest known object we have built so far, and that is on its way out to deep space is Voyager 2. It has been travelling since 1977, some 48 years, at a speed of about 55,000 km/hour. What that means is it would scoot across the entire USA in about 3 minutes time. For 48 years it has been travelling – and that is a long time, and it is still not even 1 light day away from us. It will reach that point some time next year. At that pace, it will take until the year 19862 AD to reach 1 light year. Our species will be long gone from planet Earth. That is your cosmic yardstick.

Last night I was imaging the galaxy NGC 891 shown above. I captured an hours worth of photons on this image, and this galaxy is 30 million light years distant. That means the light I captured last night was from 30 million years ago, long before humans ever walked this planet. 30 million years ago, a major glaciation event was taking place on our planet along with a mass extinction. Mammals were in control of the planet, the dinosaurs left 35 million years before in a mass asteroid impact event. Crocodiles first appeared 250 million years ago. I am saying these things to put time and distance into perspective. And even life.

When we look at space, we see calm. We see stationary patterns. Yet it is not calm, and it is not stationary. It is extremely hostile to life, with cosmic rays, extreme cold temperatures, completely void of the things we need for life. It is full of debris capable of demolishing a planet, a star, or even a galaxy. It is a lifeless, dangerous and surprisingly empty place at the same time with junk travelling at immense speeds in all directions. Two galaxies can merge, and stars never touch each other. Yet through chance, one large life altering chunk of space debris left over from the solar system formation some 4 plus billion years ago can turn a 250 million year run on planetary dominance into a species ending impact such as the one that took out the dinosaurs. It didn’t take out the crocodiles though, but it made space for the mammals to emerge and dominate our planet, if only for a brief tenure.

All of this unrelated topical writing is just to help put into perspective just what we are doing out there, when we are looking at the stars, letting our imaginations run wild, and perhaps snapping a few pictures. As one of my old professors used to say, “have a think on that.”