Neptune is often referred to as the green planet due to its striking bluish-green color, which is primarily a result of the presence of methane in its atmosphere. The planet’s atmosphere is composed of hydrogen, helium, and about 2-3% methane. While hydrogen and helium are colorless gases, methane absorbs red light and reflects blue and green light, giving Neptune its distinctive hue.
The exact shade of blue can vary depending on the amount of methane and other elements present in the atmosphere. Additionally, Neptune exhibits dynamic weather patterns and storms, which can influence its appearance. The iconic Great Dark Spot, for example, is a storm system that can alter the coloration in certain regions.
In summary, Neptune’s label as the green planet stems from its beautiful blue-green coloration due to methane absorption of light, making it a captivating object in our solar system.