I quite like to walk up hills and mountains. For this reason, I’ve come to Ireland to walk the highest peak here: Carrauntoohil.


More later, when I’ve done it.
The route up to the top takes in a semi-semi-wet waterfall: the devil’s ladder.

This was a real scramble, requiring hands, feet, knees and just about every other part of you to ascend.
From there the route was flatter and easier, mostly over scree slopes until the final push to the top.
The weather cleared several times offering a snatched view of the way we cans and the surrounding mountains and lakesimage

I arrived at the top shortly after 12 pm and a few moments after an American couple got engaged. She was ecstatic and shaking with excitement, he was shaking with nerves. Good thing she said yes, else their journey down works have been hard


The happy couple

The journey down was hard, the devil’s ladder seems much easier going up, going down you get the full experience of the almost vertical ascent, except you can see it all in front of you on the way down.
We made it with no issues, total walk time six hours.

Angular resolution of the dome of Planetarium of Majorca from Palma

WOW – what a clickbait title that is…

Back from having spent a few days between Christmas and New Year in Palma, Majorca. On the last day there I noticed I could just see the dome of the Planetarium of Majorca (or the telescope dome, I’m not sure which) from the hotel terrace. Seeing conditions were not great, but the small white point on the mountain top was clearly visible by reflected sunlight. It did look to be just on the edge of visibility, so now I’m back I wondered just how close to being invisible it really was.

Some Data:

  • Telescope dome position : 39.642528°N 2.950516°E (from wikipedia)
  • My viewing position : 39.555666°N 2.623219°E (from photographic GPS and google maps)

Positions of the dome and my viewing point

Some derived data:

  • Dome diameter : 15m (measured off google earth)
  • Distance between these points : 29.668km

Angular size :


  • 5.056×10^-4 radians
  • 0.02897 degrees
  • 1′ 44.3″ arc seconds

This seems pretty small, how’s it compare to things we’d usually see?

  • Sun diameter : 31’30″Full Moon diameter : 29’20″
  • Planet Venus at closest  : 1’00″
  • Brightest star in the sky – Sirius : 0.005936″

(All values from wikipedia)

The dome appears larger than the brightest star in the sky and roughly the same size the planet Venus does. These are both perfectly visible, so why did the dome appear just visible to me? I’m guessing it’s because the dome was only reflecting a small amount of light, and I was viewing it against quite a bright background (blue sky) too. Atmospheric haze and thermal twinkles probably didn’t help.

So although I should have been able to see it pretty clearly (if it had been emitting it’s own light, against a dark background) , I was probably pretty lucky to have seen it at all given the atmospheric conditions.

Happy new year!