Since our first contact with astronomical images, the variety of planets, stars and celestial objects in the universe enchants us. And not only because of their complexity and their characteristics that can be quite out of the ordinary. Here on Earth, we often interrupt our lives for a while to contemplate a beautiful flower or landscape. The same could be true off-planet as well. FromIn fact, there is much beauty and aesthetics in the various shapes and colors of a sky that, to the naked eye, seems dominated by dark colors and white dots.

There is, however, much in common between several of these bodies. If this were not so, we would not be able to group them into different classifications. There are stars, the giant spheres of plasmas that produce energy by thermonuclear fusion inside. And they are very different from planets, which do not produce energy, but are just agglomerations of gas or solid matter in equilibrium. Closer to theplanets, are the asteroids. In fact, between these last two categories, there may even be quite a bit of intersection.

One way or another, among similarities and differences, contemplating the beauty of the Solar System, many doubts arise. And even some that at first, would be simple. For example, what is the reason for the variety of colors among our neighboring planets?

The rocky neighbours

Image: Wikimedia Commons

Closest to us on Earth are the rocky planets of the Solar System. They are Mercury, Venus and Mars. But in fact, all the planets, and even the Sun itself, formed from the same cloud of gas, the primordial nebula. While most of the gas clustered around our central star, in the region of the planets closest to the Sun, the story was different. The greatest intensity ofradiation swept away the gas of the early planets, leaving rocks and dust to collide until they formed larger bodies.

In Mercury's case, its contents are already very visible through its gray coloration. That's because there are large amounts of iron in its small neighbor. In addition, an atmosphere so thin that it is practically irrelevant. NASA's MESSENGER mission even showed a thick layer of dust and silicates. Among the theories about its size and composition is a collision that may have rippedOr that most of the matter that could have formed it was pushed away from you in the primordial nebula.

Mars, like Mercury, has a lot of iron in its composition, and a lot of dust, by the way. Most of it is oxidized (or, as we say, rusted), which explains its red color. It is also common that the contrast of Mars' red is increased in photos to better visualize its features. The planet's visual, however, is not unremarkable.In the case of Venus, it can be difficult even to see its surface. When observing it through a simple telescope, we should see a brilliant white with yellow details. This is due to its atmosphere composed mainly of carbon dioxide. What happens there, therefore, is like an out of control greenhouse effect.

Gaseous planets: large and turbulent

Image: Wikimedia Commons

Jupiter is like a star that didn't work out. Composed mainly of hydrogen and helium, just like the Sun, it didn't reach enough mass to start nuclear fusion. The largest of the planets is entirely an atmosphere, being a big ball of gas. It also has climatic variations. A good example is the so-called Great Red Spot. This is a huge storm that can be seen up toIts color can be explained by the fact that it is at a higher altitude than most of Jupiter's gas, so it receives more radiation from the Sun. On top of all this, Jupiter has characteristic bands in the colors brown and beige.

Next to the Solar System giant is Saturn. It is perhaps the most beloved of the Solar System, due to its characteristic rings. And besides their beauty, the planet is also quite active. There are storms in the lower region of the atmosphere. From time to time they reach the surface, appearing as white spots. Like Jupiter, it is composed mainly of hydrogen and helium, with some presence of ice andMethane. Similarly, in fact, to Uranus and Neptune, the last two planets. In these cases, however, the proportion of methane is greater. There is also more ice and they are less cloudy than the atmosphere of their ringed brother. This gives them their quieter, bluer appearance.

The colour of planets, therefore, is closely linked to their physical and chemical composition. This is true even for the former planet, now downgraded to a dwarf planet, Pluto. It consists mostly of ice, with a rocky core. Among all the ice, there may be nitrogen, methane, carbon monoxide and some organic material. All this mixture could then explain its brown colour.