I will be very disappointed tonight. I already see that the Harvest Moon will not be visible at moonrise from South County Dublin at 1930 local time. The skies have clouded over and that’s it for this moon. It will rain instead.
I watched Mars last night and found Venus occupying that same position this morning. Both planet sightings were about 25 degrees above the horizon and east of me. But that may be my lot for a few days, if the weather forecast is to be believed.
What is it about the celestial bodies this year? Cloud cover for several days and I missed seeing the comet NEOWISE when it was a mere 50 million kms away, that was back in July. The rest of the time I could have seen it was either cloudy or masked by the glow of city lights.
The real annoyance today is that Mars would have been visible to me as it rose close to tonight’s full Harvest Moon. Tomorrow, they will rise at virtually the same time. This is a photographic opportunity lost to me. I’d already worked out where to place the tripod in order to stand the best chance of having the moon rise behind a lighthouse knowing that there’s always a risk of cloud at these temperate latitudes.
Happily, this month has yet more potential for celestial sightings. Mars is in opposition, very large and as close to Earth as it will be until 2035. It’s almost as big as it was in 2018 but back then, it was too close to the horizon to see with fidelity. Then again, Mars will be its brightest since 2003.
And there is second full moon on October 31.
A couple of things to clarify. Being in celestial opposition simply means that celestial objects are directly opposite the sun. They reflect the light and so they appear much brighter to our eyes. Two full moons in a month doesn’t really make the second a Blue Moon though it’s become commonplace to express it thus. It’s wrong on two counts.
First, the moon almost certainly won’t be blue. It does happen, for example, in 1883 after the eruption of Krakatoa but there’s rarely enough dust in the atmosphere to make it happen again. Perhaps the global forest fires will change that for October 31st?
And secondly, the original definition of the blue moon was the third in a season that has four moons.
Let’s not worry about the true definition of the Blue Moon. Two moons in a month? Call the second Blue, like the one that hangs in our living room.
I’ll look forward to seeing Mars full, big and red around the 6th of October and the moon full, big, and blue on the 31st.