u/WhiskeyFox9

I am just starting to learn about the local geology. The estuary is fringed by various outcrops, spanning the Jurassic up to the Quaternary periods, some with all kinds of marine fossils. A little inland, the catchment area lies in a mountainous region with formations dating all the way back to the Ordovician period.

I scratched around the river mouth where the Salnova formation (<2my) offers various shells.

Next up will be the Alexandria formation (Tertiary period) and Sundays river formation (Cretaceous) where I hope to find some shark teeth and ammonites.

I recently made a YT video that explains flow through a venturi at the molecular level. The sim code is written in Processing.

I had some remnant code from an earlier simulation, and accidentally hit a key programmed to trigger a pressure pulse. The top image shows the pressure contribution of individual molecules, i.e. collision impulse magniude and frequency avaraged over a time interval. Bottom image shows drift velocity, again averaged over time.

Molecules exiting the screen to the right are inserted back into the high pressure region on the left.

You can clearly see the diverging flow go supersonic at some point, as well as a normal shock downstream.

Here is a link to the molecular flow explanation: https://youtu.be/7OAIH0vpZBc

Taken by me.

This is a single 30s exposure of Omega Centauri.

Skywatcher 150 Mak, Canon 250D.

I have taken many photos that get streaked by satelites, but I have not seen any with a bright spot at the end of its trail, such as these have. Is there an explanation for the oscillation in trail that exits bottom right? The shear amount (many are barely visible) and variation in brightness make me wonder if I, by sheer luck, managed to capture a disintegrating meteor. I just noted another oddity. A handful of "stars" have very short trails, pointing down and left. Any thoughts?

A sequence taken early 2025. I believe the shadow was cast by Io.

Skywatcher 150 Mak, Canon 250 with 2.5x Barlow.

Each image started as a 30 second video, then processed into a stacked image in Registax.

Taken from Port Elizabeth, South Africa.

Lots of air turbulence, the image was swimming in an out of focus, dancing and wobbling all over in the video. It is amazing what these image processing packages are capable of.

Early this year, I almost managed to capture a double eclipse. I got a glimpse through a gap in the clouds, but not enough time to focus properly. I hope someone else managed to capture it!

Programmed in Processing. I struggled to get well-defined spiral structures in 2D, but the 3D model looks much better. It did require careful initial position and velocity distribution. There is a fixed "black hole" at the center. Stars come in only two masses, the majority being lower mass.

Programmed in Processing. I used an oct-tree for the 3D simulations. The swimming motion of the worms results from directional instability, i.e. a segment is attracted more to the one ahead of it than vice versa.

This simulation shows the initial pressure field development around a trailing edge. Edge thickness is 2mm on a foil of 1m chord. Streamlines give an idea of momentary flow direction at a given instant. It should be kept in mind that the pressure field changes rapidly and that a particular air particle might only move a very short distance before its underlying streamline again changes direction. This was part of an investigation into the time-dependent development of lift. Initial air movement creates a strong surface pressure disturbance, which refracts as a wave around the corners.