Thread by @ProfHughLewis

For those asking, this visualisation is made up exclusively of a single Excel chart (2D scatter plot) that contains multiple series. Some of the data are plotted as lines without markers, some are plotted just with markers. Spin buttons provide real-time updates.

I convert the Keplerian elements for the orbit to Cartesian coordinates and then project the 3D position onto a 2D plane (that is plotted). I do this for true anomaly values between 0 and 360 deg. to get the orbit.

The "Earth" is drawn in the same way. In fact, the lines of longitude are essentially circular, polar "orbits" with radius equal to the Earth radius. Lines of latitude are circular, equatorial orbits that are translated and re-sized.

I use the angle between the orbit radius & the viewer (plus some radius checking) to see if the point is hidden behind the Earth. If it is, I use "#NA" for the coordinates of the point so it is not drawn in the scatter plot. I draw a dashed line with a separate series instead.

The glowing Earth limb is just a circle (with added glow)drawn on the 2D scatter plot with a radius equal to the maximum distance of the Equatorial line from the origin.

It should be straightforward (but time-consuming) to add additional orbits if you wanted to visualise a constellation, for example. As long as you can define the orbit of each plane in the constellation, the same rotations and projections will apply. That's something I will add.

I am also aiming to add a conversion to latitude and longitude so that the ground track over several orbits can be visualised.

Please get in touch if you have any other suggestions for additions!