You can use Object coordinates for this

1. Use Texture coordinates > Objects and target the dome
2. Use one ColorRamp for Base Color
3. Use another ColorRamp for alpha channel

You can use Object coordinates for this

1. Use Texture coordinates > Objects and target the dome
2. Use one ColorRamp for Base Color
3. Use another ColorRamp for alpha channel

Here a simple setup how you could realize it with two objects, which define the color of a third object: