In our Solar System, we can see planets with remarkable colors which, when studied, tells scientists a lot about their origins and formation.
Venus, the brightest object in the sky after the Sun and the Moon, acquires its unique white-yellow color from its atmosphere, featuring a thick cloud layer rich with sulfur compounds, which are responsible for the yellow coloring. Sulfur also reflects about 70% of the sunlight, making the planet brighter, though farther from the Sun than Mercury.
Mars, the Red Planet, is red because of its surface material, which contains lots of iron oxide; the same compound that gives blood and rust their hue. Just like Earth, Mars had large amounts of iron when created. Yet, due to the Earth’s larger size and stronger gravity, iron sank to its core. On Mars, however, abundant iron remained in upper layers. Exposed to oxygen and some sort of weathering conditions over long years, surface iron gradually rusted, leading to Mars’ reddish color.
Jupiter, the Solar System’s largest planet reflects many shades of white, red, orange, brown, and yellow. Changes in Jupiter’s colors is subject to storms taking place in its atmosphere; these storms allow different chemicals to rise from areas closer to the planet’s core to the tops of the clouds. As different chemicals reflect the Sun’s light in different colors, the previously mentioned set of colors appear dotting Jupiter’s atmosphere. An extreme case in point is Jupiter’s Great Red Spot, which marks a storm system that has been raging for at least 400 years now.
Unsurprisingly, the color of Uranus and Neptune comes from their atmospheres. Though helium and hydrogen are the most abundant molecules on the two planets’ atmospheres, it is Methane, the third most common molecule, which gives them their colors. When sunlight hits Uranus and Neptune, some of the spectrum lights are reflected back into space and some are absorbed. Methane is more likely to absorb colors at the yellow-red end of the spectrum, and reflect those at the blue-green end; that is why Uranus is blue-green and Neptune is a bright azure blue.
Cosmic colors are the key to a fascinating myriad of universal secrets; studying them has and continues to unravel explanations that would help us further understand the universe, its origin, its evolution, and, maybe, its future.
*Published in PSC Newsletter, 2nd School Semester 2012/2013 issue.
References
telegraph.co.uk
pha.jhu.edu
nasa.gov
science.howstuffworks.com
huffingtonpost.com
universetoday.com
news.bbc.co.uk
moonphases.info
aerospaceguide.net