Here's why:

* Liquid oxygen: The pale blue color arises due to the absorption of red light in the visible spectrum by the oxygen molecules.

* Solid oxygen: The pale bluish-white color is a result of the increased density and molecular interactions in the solid state, leading to stronger absorption of red light and increased reflection of other colors.

It's important to note that the colors are quite subtle, and the actual shade can vary depending on factors like the purity of the oxygen and the lighting conditions.