Mercury 101 A World of Extremes (4K UHD)

The planet Mercury, a world of extremes that bears the scars of a violent history. This small planet is often thought of as just a barren rock floating through space, but Mercury is a fascinating world of bizarre mysteries that are only just beginning to be unravelled. Named after the Roman god of shopkeepers, merchants, travellers and thieves, but also commonly identified with the Greek swift-footed messenger of the gods Hermes, Mercury is the smallest of the eight main planets that help to make up the solar system. It has a diameter of 3,032 miles across, which is 4,879 kilometres across, making it slightly larger than Earth's moon. Just like its neighbours Venus, Earth and Mars, Mercury is classed as a terrestrial or rocky planet that likely formed 4.5 billion years ago, when gravity pulled swirling gas and dust together. It has a solid surface that is covered in craters similar to the moon, a rocky mantle that is only 250 miles or 400 kilometres thick, a molten metal outer core and a massive solid metal inner core that makes up nearly 85% of the planet's volume. Mercury is the closest planet to the sun and has to endure the full force of our star's glare, causing dramatic temperature changes across the tortured world. On its sun-facing side, it can rise to a scorching 427 degrees Celsius, which is 800 degrees Fahrenheit and is hot enough to melt lead. Whereas on the dark side, the temperature can plummet to a frigid minus 180 degrees Celsius, which is minus 292 degrees Fahrenheit. Although Mercury is very close to the sun, it isn't the hottest planet in solar system however, as that title belongs to our cloud-covered neighbour, Venus. Mercury follows an elliptical, oval-shaped orbit that takes about 88 Earth days to complete. It travels through space faster than any other planet in the solar system, a rapid 29 miles or 47 kilometres every second. However, one day on Mercury is extremely long due to its slow spin, taking one rotation nearly 59 Earth days. Instead of a thick atmosphere, Mercury has what is known as an exosphere, which is mostly composed of Oxygen, Sodium, Hydrogen, Helium and Potassium. The tenuous exosphere is created by solar wind, volcanic outgassing and debris that has been kicked up by striking meteoroids. And without constant replenishment, the atoms that make up the exosphere would likely be stripped away into space relatively quickly. Since Mercury has no real protective atmosphere to help burn up incoming meteoroids or asteroids, the planet is riddled with impact craters. The largest crater, known as the Caloris Basin, was caused by an enormous object that struck the planet with an impact equal to that of 1 trillion megaton bombs, leaving a colossal crater roughly 950 miles or 1525 kilometres across. Because Mercury is so close to the Sun, it is the hardest of all the inner planets to observe from Earth, arguably making it the most enigmatic of the rocky worlds. However, at certain times of the year and with an unobstructed horizon, you can see it with just the naked eye, as it appears as a bright, yellowish star in the evening just after sunset or in the morning just before sunrise. Mercury can also be observed 13 times a century passing across the face of the Sun during an event called a transit. So far, only two spacecraft have visited Mercury, making it one of the least explored planets in the solar system. The first was Mariner 10, which imaged about 45% of its surface, discovered Mercury's thin exosphere and detected its magnetic field. The second was the Messenger spacecraft, which orbited the planet for four years and completed mapping 100% of Mercury's surface, while collecting groundbreaking data that changed the way we think about the small planet. Messenger eventually came to the end of its mission in April 2015 and crashed into Mercury's surface, providing the desolate world with one more crater. But there is currently another spacecraft on its way that is expected to arrive there in late 2025. The BepiColombo spacecraft is a European Space Agency mission that will explore the tortured world and attempt to solve many more of Mercury's fascinating mysteries.