To animate the sky, I set up a fractional variable that represented the progression of the entire day. From 0.0 to 0.4 it's night, followed by a 10% sunrise transition (0.4 to 0.5) that blends into full daylight for the next 40% (0.5 to 0.9), before the final 10% fades smoothly through a colorful sunset and back into darkness.

To bring the background to life, 40 stars were randomly scattered across the screen. During the night cycle, I used a sine wave paired with that phase offset so that each star twinkles independently rather than flashing in unison. Shooting star also occasionally streak across the dark sky.

For the clouds, I built a continuous scrolling effect using three distinct cloud objects—drawn with overlapping circles—that pan from left to right at varying speeds. Whenever a cloud drifts completely off the right edge of the screen, it automatically wraps back around to the left side and is assigned a new random altitude.

Northern lights are triggered every third night. They're generated by intersecting sine and cosine waves. To optimize rendering, I skipped per-pixel gradients; instead, the code steps across the screen drawing vertical lines in 3-pixel chunks, smoothly fading between three colors to build the gradient dynamically.

A technical issue I encountered whilst working on the Northern lights was the appearance of harsh horizontal borders between the different colours of the aurora. This problem happened because different colours of the aurora were initially divided into three large, solid colour blocks (cTop, cMid, and cBot) with the colours blended with in those blocks. This created abrupt transitions where one colour suddenly ended and the next began rather than a smooth fade. To resolve this, the code was rewritten to mathematically blend the colors along the Y-axis. By calculating a smooth vertical gradient in 3-pixel chunks, the aurora now transitions seamlessly from the top color to the bottom color without any horizontal cuts.