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Rimae Hippalus


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This photo for me has a nostalgic flavor. It always reminds me of my beginnings in astrophotography.
About 13 years ago, as soon as I bought my first large telescope (Newton GSO 12" f/5 from the late Armazém do Telescopio) I became good friends with master Darío Pires, and it was based on his practical and theoretical teachings from my great friend Ilídio Afonso who started me in this art.
When I started taking pictures, I used the Newton on a Dobsonian basis, with a generic Fuji camera and I did afocal photography guided by my arm, I remember well that I coveted the fantastic images of the group that had specialized equipment.
Among these old photos, one caught my attention a lot, it was a photo by Mestre Darío Pires of this set of Rimae parallel in curve. I remember Darío took this photo with a DBK 21AU, using if I'm not mistaken that famous 400mm that Fabio Plocos has today.
I thought to myself.... "One day I'll take a picture like this."
It's not the first time I've photographed Rimae Hippalus, but whenever I do, I can't help but be reminded of this fact.

Concentric channels are one of the most impressive features on the moon, and one of the best examples is Rimae Hippalus, an arc around the east side of Mare Humorum. To the northeast and next to Hippalus a strange thing happens, there are some Rimae in a concave arch. The most notable one is called Rima Agatharchides, but is it actually part of Rimae Hippalus and family?
Rima, Rimae in the plural (Channel) or for some Selenogists Rille (narrow valley), is a fissure or lava channel that has totally or partially collapsed.
Rima and Hippalus are curved channels, faults caused by stress in the crust. Some sinuous channels are believed to have formed by the rapid movement of lava flow, but there are some that originate from the collapse of lava tubes under the collapsed surface. However, I firmly believe that in the case of Hippalus, the origin was the tension in the crust due to the impact of a colossal body that formed the Mare Humorum, and that would be the true responsible for this set of rilles.
In fact, in this photo you can see at least one more set of channels called Rimae Ramsden, a set of very branched rilles around the crater of the same name.
A bonus that I really liked in this photo was how easy it was to notice that the Marth crater is actually a concentric crater, watch it carefully in the lower left corner.
I hope that colleagues, like myself, have fond memories of their beginnings in astrophotography, humbly remember how they started, and put what they have now to good use.


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Excellent image. One of my favourite areas to image due to the riles. They look really sharp. I enjoyed your write up as always, very insightful.

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