Sunday, 12 February 2017

Almost invisible, but that's the challenge

What is it that pushes us astronomers to go hunting those little blobs so faint that you almost need a healthy dose of imagination in order to see them? Why are we so passionate about staring through a small hole for hours in the biting cold until we eventually think that we've seen "something"? The answers's very simple: because it's a challenge! Because we want to be able to raise our heads and say to the world that we've seen it. Or because we want to discover something that no-one has ever discovered before. Of course, in these days of Hubble and high-definition photography there's anything left for us amateurs to discover with our limited telescopes and poor human eyes. But we don't want to give up and stubbornly try to push our observations to the limits. There's barely a challenge in observing the Orion Nebula or a bright star cluster. But there is a challenge in observing... ARO 215 for example. What the heck is ARO 215 (also known as Abell 7) anyway? It's an old planetary nebula in the constellation of Lepus, the hare, that's become so large that it's almost completely dissipated into space. This is an object that's reserved for the largest of telescopes or, better still, a big binoscope because this instrument allows you to observe at lower magnifications for the same light-gathering power. Since ARO 215 is quite large with its 13 arc minutes diameter, you need as low a magnification as you can get in order to observe it. The sketch below represents very well how I saw it with my 18" binoscope. Are you getting the idea of how faint it is? The Medusa was faint, but this... must've been the faintest object I've observed so far! 

Aren't you seeing anything? I advise you to turn off the lights and to have another look. Go on... concentrate, as I had to do behind the telescope. You didn't think that I was going to make things easy, did you? Use averted vision because your eyes are more sensitive to light next to the point where they focus. Now are you seeing something? You may even discover that I saw two distinct lobes in this planetary with the left one marginally brighter than the one on the right. And that... dear readers... is the kick that we astronomy-weirdoes are so addicted to!

No comments:

Post a comment