The Moon Calendar 2020 displays the moon’s phase for every day of the year in a grid, with months on the y-axis and days on the x-axis. Each moon is rendered as an orthographic projection of a circle using `d3.geoPath` and `d3.geoOrthographic`, with phase computed from a simple lunar-cycle formula. Clicking anywhere highlights the current day’s moon with a fading red ring, animated via `transition`. The visualization uses `d3.scaleLinear` for days, `d3.scalePoint` for months, and `d3.timeDays` to generate the date sequence.