The solar system planets vary significantly in color due to the composition of their surfaces and atmospheres and how these absorb and reflect light.
Earth, Venus, Mars and Jupiter each feature unique hues; Uranus and Neptune all share similar attributes as well.
Earth
Our solar system’s planets take on their colors based on various factors. This may include their proximity to the Sun, their physical characteristics and geological history.
The most distinguishing trait between Venus, Mars and Uranus/Neptune atmospheres lies in their respective hues which determine if they reflect light or absorb it; Venus/Mars atmospheres reflect blue while Uranus/Neptune absorb red light.
Earth’s atmosphere is dense enough for photons of red, orange and yellow light to reach our eyes without scattering; this explains why midday sunshine looks blue while at sunset it becomes whiter in hue.
Mars, our neighboring planet, is a cold desert planet covered with reddish iron oxide dust that gives it its distinctive red hue. Oxidized and rusted dust also generates various storm systems on Mars from localized tornadoes to planet-engulfing dust storms.
As our solar system took millions of years to form, its planets gradually developed differently – leading to each planet having unique atmosphere and surface characteristics from when it first came into being.
Venus
Venus, one of our solar system’s fascinating planets, has long captivated humankind. Dubbed after the Roman goddess of love, Venus stands out with her striking beauty and striking features.
Venus is believed to have an array of colors ranging from creamy yellow to bright and sunny yellow due to the way light is absorbed by carbon dioxide and sulfur dioxide composing its atmosphere.
Due to Venus’ yellowish hue, surface features may be difficult to see from orbit. However, taking pictures at different wavelengths provides a much more accurate depiction of its hue.
Scientists theorize that Venus’ vibrant hue is determined by its dense atmosphere and thick clouds that cover it, known as blue absorbers which absorb most of the sunlight that hits them.
Mars
Our solar system’s planets display different hues depending on their surface materials and atmospheres, as well as how much light they reflect off of or absorb from sunlight. Terrestrial (rocky) planets such as Mercury, Venus and Mars boast reflective surfaces while gas giants Jupiter, Saturn, Uranus and Neptune have atmospheres which scatter it.
Mars is well known for its distinctive red hue, due to the oxidization of iron oxide found in its rocks, regolith and dust layers.
However, this rusty dust does not have a uniform hue but instead features various browns and reds dependent upon minerals present on Mars’ surface. These hues were witnessed by Spirit and Opportunity when taking samples from this rusty dust for further study.
Mars’ atmosphere looks red due to a phenomenon known as Rayleigh scattering. On Earth, Rayleigh scattering occurs when smaller particles in the atmosphere scatter longer wavelengths of light such as blue light.
Jupiter
Jupiter is one of the most iconic planets in our solar system. A gas giant, it is well-known for its spectacular swirling clouds formed of various trace gases.
Jupiter’s atmosphere consists mainly of hydrogen and helium molecules, but there are also ammonia crystals and water ice in its topmost clouds that contribute to its distinctive orange, brown and yellow colors. These substances help explain its vivid hues.
Jupiter’s unique hues can also be attributed to powerful storms generated by convection currents in its atmosphere, which bring chemical material from Jupiter’s core into its clouds in forms such as phosphorus, sulfur and hydrocarbons.
Astronomers use Jupiter’s colors to gain an understanding of its atmospheric workings. Future missions are planned to further investigate these processes as well as learning more about Io’s volcanoes and Europa’s water ice.
Saturn
Saturn is the second-largest planet in our solar system and one of the most striking in terms of color. While its atmosphere is pale yellow, Saturn boasts beautiful rings and moons whose hue changes depending on where they fall within its rings system.
Saturn, like Jupiter, is composed of 94% hydrogen and 6% helium. Its atmosphere contains ammonia ice crystals as well as methane gas that interacts with solar radiation via methane photolysis – similar processes are observed on Jupiter.
Scientists posit that ammonia and methane particles contribute to the pale yellow hue of our planet’s outer atmosphere. Additionally, water vapor and molecular hydrogen influence this layer through cloud cover above.
The rings of Saturn can be seen from Earth-based telescopes and consist mostly of billions of tiny ice particles mixed in with some rock, dust and debris particles. Their colour depends on how far away from Saturn they are and how much sunlight is reflected back at them.
Uranus
Uranus is an ice giant composed of predominantly hydrogen and helium with trace amounts of methane that absorb red light, giving its characteristic blue-green hue.
Uranus has an atmosphere with a minimum temperature of 49K, colder than Neptune’s. This atmosphere makes Uranus featureless and cold in some regions – to such an extent that spacecraft would never be able to land there without being destroyed by its atmosphere.
Voyager 2’s flyby of Earth in 1986 revealed two bands on its southern hemisphere; these may have been methane clouds formed at pressures between 1.3 to 2 bar.
Astronomers have long wondered why Neptune and Uranus display such different shades of blue; had their atmospheres been identical, both would appear equally blue. Now researchers think they know why. By creating a model which matches observations of both worlds, researchers discovered that excess haze builds up in Uranus’ stagnant atmosphere creating whiter tones than Neptune.
Neptune
Astronomers have long struggled to explain why our solar system’s two outer planets appear slightly different shades of blue; Neptune often described as being “azure,” while Uranus tends towards “cyan.”
Reasons for such differences could include the presence of haze particles in their atmospheres, created through interactions between sunlight and atmospheres of planets.
When sunlight hits these haze particles, they absorb red light before emitting blue light back onto planet’s surfaces – creating the characteristic blue hues seen both Neptune and Uranus.
Uranus differs from Neptune in that its atmosphere has thicker and denser haze layers than Neptune’s; this means less of the sun’s blue light is reflected back onto Uranus giving its atmosphere a lighter blue hue.
Researchers used observations from the Gemini North Telescope, Hubble Space Telescope, and other astronomical data sources to create an atmospheric model for Neptune and Uranus using observations from these telescopes and others. Not only does the model explain differences in coloration between them, it also shows why Neptune experiences storms and dark spots similar to Jupiter’s Great Red Spot.
Pluto
Pluto is a planet with an extraordinary variety of surface colors due to the combination of snowfall, glaciers and chemical byproducts derived from exposure to solar radiation over an extended period of time.
The dwarf planet’s surface is covered in shades of red, brown, light gray and yellow resulting from methane gas being the third-most prevalent substance present in its atmosphere.
Pluto is thought to have a solid core made up of rock material and may even possess an ocean beneath the surface, due to being so cold with its internal pressure being much lower than its temperature allowing liquid water to exist underneath its surface.
NASA recently shared a picture of Pluto that displays its various colour variations across its surface. Taken by New Horizons spacecraft on 14 July 2015, and now available to view by all. This picture was produced through refined calibration of data gathered by their color Multispectral Visible Imaging Camera (MVIC).