Mercury Transit

Or ‘Why Polar Alignment is Important’

We were lucky enough to have a clear, sunny day here in Norwich for a large part of Mercury’s transit across the sun on Monday 9th May. So out we went with our little Lunt 35mm H-alpha scope, an Atik GP, a laptop and a large box, and about 6 and a half hours later (plus some rather hectic data sorting) here’s a quick look back at this rare celestial event:

As you may have noticed in the video and implied above, we have to hold our hands up to using fairly poor polar alignment so we had some pretty substantial drifting in our tracking. Our field of view with this combination is too small to get the entire solar disc on the chip, even when perfectly centred, so any drift tends to result in notable cropping. You’ll also notice we had some clouds come through, and unfortunately we weren’t able to record the entire transit, falling short by around an hour and a half.

This was Mercury’s first transit across the sun since 2006, and although it will happen next in 2019, if you miss that one, you’ll be waiting until 2032. The tilt of Mercury’s orbit is what makes it rare for these three bodies to align, though fortunately for us not as rare as a transit of Venus, which won’t occur again until 2117.

We’ve only done some quick and dirty processing so far and I think there’s more to be had with our data, including the potential to create a composite image of the transit from our best frames which we’ll share with you if and when we have it. But for now, we’ll leave you with our most curious image of the day:

Back to News