Is it the oldest or the youngest planet? You might be astonished to learn that there are no oldest or youngest planets. Mercury is the same age as the rest of the planets in the solar system, at around 4.6 billion years. It was once a hot molten mass with a water ocean under its crust. As it cooled, this ocean would have frozen into ice caps and then later into rock.
How did Mercury get its name? The ancient Greeks believed that the god Hermes brought up to the attention of the activity of the planet Mercury, which they called "merkury". Today, we know this isn't true, but nonetheless, Mercury is often referred to as "the messenger from Mars".
No, but many people choose to call it by its number: Mercury is the second planet from the Sun.
Are all planets Earth-like? No, not even close. Venus is a greenhouse gas atmosphere with oceans of superheated sulfuric acid. It's also very dense - 915 kg/m3 compared to Earth's 1 kg/m3. This makes it highly resistant to erosion and incapable of supporting life as we know it. Then there's Pluto, which used to be considered a planet until it was demoted to dwarf planet in 2006.
Mercury is an extraordinary planet in a number of ways. It has the shortest year (a revolution time of 88 days) and gets the most intense solar radiation of all the planets due to its closeness to the Sun—its typical orbital distance is 58 million km (36 million miles). These factors combine to create very changeable conditions: severe temperature variations and dramatic changes in light intensity. The planet's surface is also subject to violent storms and other phenomena that can destroy or deposit large quantities of material.
These effects have had an impact on life as we know it on Mercury. The most significant fact about Mercury is its atmosphere, which is made up of particles of dust and gases such as carbon dioxide, oxygen, nitrogen, and hydrogen. The atmosphere is so tenuous that only 1 percent of the energy radiated by the sun reaches the surface. Most of what does reach it comes in high-energy particles from deep within the planetary body.
The result is that Mercury is extremely cold. Average temperatures vary between -180°C (-292°F) at the nightside to +150°C (+302°F) at the dayside. Even though it has no moon to reflect any light of its own, much of the time it looks dark because of the cloud cover. Occasionally the clouds clear away to reveal some of the most beautiful sights in our solar system.
Mercury is the smallest planet in our solar system, while Jupiter is the biggest. They both have a metallic color, but that's about all they have in common.
Jupiter is more than 100 times as massive as Earth, whereas Mercury has only about three-quarters of Earth's mass.
However, the two planets are very similar in many ways. Both have very thin atmospheres made up of gas molecules. The air inside Jupiter is made up of hydrogen gas with some helium and other gases mixed in. The atmosphere of Mercury is also mostly made up of hydrogen with some helium and oxygen.
Both planets have very strong magnetic fields generated by their cores that deflect particles from their suns' outflows called winds. These particles collide with the surfaces of both planets, creating the geology we see today.
Jupiter has four major moons: Jupiter, Europa, Gaea, and Io. All four were discovered by Galileo Galilei in 1610. He was looking through a telescope made by his son Vincenzio when he saw these objects moving across the night sky.
However, other scientists have discovered evidence from a massive impact crater that looks to be more recent, leading them to assume that Mercury may have seen volcanic activity as recently as 1 to 2 billion years ago. In either scenario, Mercury's volcanic stage has long ago gone.
Volcanism is a major part of Earth's surface and planetary evolution. Volcanoes are important elements in creating environments suitable for life. They can also destroy those same environments by releasing gases that create clouds and aerosols which block out sunlight and cause global warming.
Although Venus and Mars have large amounts of volcanism today, they used to be much more active at one time. All three planets in the Solar System formed around 4.5 billion years ago. Then, about 700 million years later, all three began to cool down and shrink. This is because as they cooled down, their gravitational forces decreased, which led to less frequent collisions between themselves and their moons. These collisions reduced the amount of energy they received. Over time, both Mars and Venus shrank until they became completely covered in carbon dioxide gas. Today, Mars is only 39% as wide as it was, while Venus is 85% as wide as it was.
During this time on Earth, there was no evidence of any volcanism except for some small earthquakes here and there. This is because we're not used to living on such a quiet planet.