Vertical Pixel Space Shooter Background

Create a vertical, retro pixel-style scrolling background for a space shooter game, designed as a seamless mobile game asset. The canvas uses a high-ratio 9:16 vertical screen frame, with a dark central flight path left mostly blank for gameplay. The scene is filled with a deep black starry sky, adorned with hundreds of tiny white, blue, and purple pixel stars, and two luminous vertical nebula streams: a winding, electric purple-blue nebula on the left and a purple nebula with cyan highlights on the right. Add three clearly visible planets: a large purple cratered planet at the upper left edge, a partially cropped blue-purple outlined planet at the lower right edge, and a small purple moon below the lower right planet. Add 22 rocky asteroids of varying sizes, irregularly shaped, cratered grayish-brown with purple shading, distributed around the edges while keeping the central area open: one large asteroid near the top right corner, one medium-sized asteroid on the right central edge, one medium-sized asteroid on the bottom left edge, one large asteroid cropped in the bottom left corner, one large asteroid cropped in the bottom right corner, and the remaining 17 smaller asteroids scattered along the top, sides, and bottom edges. Use a crisp pixel art rendering with high-detail jitter, thick jagged outlines, bright edge highlights, no vector smoothing, no spaceships, no UI, no text, and no watermarks. Color palette: black space, magenta nebulae, electric blue accents, white starlight, and gray rocky asteroids with cool purple shading. The image should have a production-ready vertical flight shooter background effect, both dramatic and highly readable, ensuring a clear central game path.