The moon appears orange at night primarily because of its low position near the horizon. When the moon is low, its light has to pass through a larger thickness of Earth's atmosphere. This atmospheric layer scatters shorter blue wavelengths of light more effectively, allowing longer red and orange wavelengths to be more dominant when they reach the observer. This is the same phenomenon that causes sunsets to appear orange or red. Additionally, the moon can appear orange due to atmospheric particles like smoke or pollution filtering the light further. This effect is most noticeable when the moon is close to the horizon and diminishes as it rises higher in the sky, where it appears whiter or more silvery.
In some years, rarer astronomical events such as lunar standstills or lunar eclipses can enhance color changes, including deep oranges and reds, due to the way sunlight is filtered through Earth's atmosphere and how the moon's position aligns with the Earth's shadow.
Thus, the orange color of the moon seen tonight in 2023 is mainly due to the scattering of light through the Earth's atmosphere when the moon is low on the horizon.
