Mercury Just Revealed Something That Breaks Physics

[00:00:00]Mercury, a small, barren world circling the Sun at close distance, [music] might appear the least intriguing planet in our solar system. And we still don't know much about this tiny celestial neighbor.

[00:00:12]Even though on average Mercury's orbit comes the closest to planet Earth out of all the other planets, we've only sent two missions to study it. But the more we discover about the planet, the weirder it becomes. One of the most surprising things is that scientists [music] think Mercury originated in a different corner of the solar system.

[00:00:31]And there's some other surprising things about Mercury that we've just discovered that you won't believe is possible. Now, get ready >> [music] >> as we explore Mercury and unlock the secrets it holds.

[00:00:52]Every 88 Earth days, Mercury circles the Sun at a speed of approximately 29 miles per second, which makes it the fastest planet in the solar system. It's also the tiniest among the eight planets in our cosmic neighborhood. With a diameter of about 3,000 miles, Mercury is just a little larger than the Moon.

[00:01:10]>> [music] >> But scientists believe it hasn't always been like this.

[00:01:14]Mercury's core makes up roughly 85% of the planet's diameter and approximately three-quarters of the planet's mass.

[00:01:22]It's outer part is liquid metal, while the inner core is solid iron, almost as big as Earth's inner solid core.

[00:01:29]But because Mercury is much smaller compared to the other solar system's rocky worlds, the [music] planet's proportions have scientists puzzled. One idea that might explain the unusual size of Mercury's core compared to its overall diameter is a huge impact in the planet's past. Some scientists think that billions of years ago, Mercury might have collided with another celestial body.

[00:01:53]>> [music] >> The impact changed the planet's trajectory, pushing it closer to the Sun and removed most of Mercury's crust.

[00:02:00]It's as if the crust of Mercury was peeled off in layers over time.

[00:02:04]We know that approximately 4.5 billion years ago, Earth was impacted by an unidentified celestial object and there is speculation among researchers that this object might have been Mercury and the remnants of this collision eventually merged to form the Moon.

[00:02:20]If this hypothesis holds true, it suggests that our satellite could potentially be composed of the missing outer layers of crust of the closest planet to the Sun.

[00:02:31]The two space objects do indeed appear similar, but another theory suggests that Mercury's unique composition can be explained by the [music] early solar nebula.

[00:02:40]During this period, there was a lot of dust and gas, including small pieces of iron orbiting the young Sun.

[00:02:47]As the Sun's gravity and its magnetic field pulled those iron grains closer, the planets forming nearby took more iron into their composition and gravity compressed it into their cores.

[00:02:59]The idea fits well with the proportions of the solar system's rocky planets with Earth and Venus having cores about 1/3 of their mass with Mars containing the smallest core of our four rocky worlds.

[00:03:10]But there's one problem with this theory. If we look into data from NASA's MESSENGER space probe, Mercury's composition contains too much of the chemical element potassium. Why is this important? Potassium is extremely volatile and it evaporates fast on planets with high temperatures. So, at least in the solar system, the planets that were created in a closer orbit around the Sun shouldn't contain high amounts of this chemical. Instead, they would be rich in thorium, a much more stable chemical element that can withstand extremely hot conditions.

[00:03:44]But here's the twist. The ratio of potassium to thorium observed on Mercury closely resembles that found on Mars.

[00:03:51]So, there's a chance that for a long time the closest planet to the Sun might have been Venus and Mercury used to orbit the Sun at a distance that Mars currently is. And if Mercury actually collided with Earth 4 and 1/2 billion years ago, the impact could be the reason behind the position of the solar system's planets we observe currently.

[00:04:11]But, there could be one more factor in play that made Mercury smaller.

[00:04:17]For the past 3 billion years or so, the planet has been shrinking in size and scientists believe it might be doing so even today. As Mercury's core loses heat involved in its formation, it shrinks.

[00:04:30]This makes the crust of the planet snap and form thrust faults. So, the surface of the entire planet contracts as well.

[00:04:37]One indication of this is the presence of these peculiar landforms called lobate scarps on Mercury, some of which are hundreds of miles in length. Just imagine Mercury as an apple drying out from the inside, which causes wrinkles all over its surface. By studying thousands of these structures, scientists have calculated that Mercury's radius has reduced by roughly 12 miles since its formation.

[00:05:02]Now, a planet this small isn't supposed to have any magnetic field, but Mercury does have one. Although it's just 1% that of Earth's, it can still reflect some of the Sun's stellar winds and even cause magnetic tornadoes on the planet's surface.

[00:05:17]Among the solar system's rocky worlds, only Mercury and Earth have a magnetic field. To power a magnetic field, a planet has to have molten metal in its core and it should spin relatively fast to keep that liquid metal moving.

[00:05:31]But, because the innermost planet is so tiny, researchers thought its entire core had long cooled. Additionally, Mercury's rotation around its axis is extremely slow with one day there lasting about 58 Earth [music] days.

[00:05:44]But, then researchers discovered ancient magnetized rocks in the planet's craters. By studying these rocks, scientists have calculated that Mercury has a magnetic field for about 3.8 billion years of its existence, and it may have once been 100 times stronger than the Earth's magnetic field is today.

[00:06:02]Because solar wind particles are like moving electric charges, they also carry a magnetic field, but a much stronger one. As the solar wind reaches the planet, the two magnetic fields collide, and they can sometimes twist together, giving rise to tornadoes that can appear and disappear within minutes.

[00:06:20]On Earth, tornadoes form in the clouds and carry around a lot of dust and debris. But, since Mercury doesn't have any clouds, dust, or wind, tornadoes there are unlike anything you've ever seen.

[00:06:32]They are invisible and enormous in size, stretching from outer space to the planet's surface. Scientists believe such a magnetic tornado can reach the width of the entire planet.

[00:06:45]On its surface, Mercury's even weirder.

[00:06:48]Despite its close proximity to the Sun and the scorching temperature, there's water ice on this planet. When the Messenger space probe studied Mercury, it detected light reflections around the planet's poles. And, even though scientists haven't observed this ice directly yet, there's a big chance it's there.

[00:07:06]Because of Mercury's little axial tilt, the planet's poles do not receive as much direct sunlight as Earth. Some craters at Mercury's polar regions are in constant [music] shadow. That, combined with almost no atmosphere to trap heat, allows them to remain cold at times.

[00:07:23]What scientists struggle to understand is the origin of that ice. Mercury hasn't been bombarded by icy comets as much as Earth in the past because of the Sun's gravitational pull.

[00:07:34]Although recent research might have an answer, and it's a bizarre one.

[00:07:38]The idea is that the Sun helps create ice on Mercury. But, how is that even possible?

[00:07:44]On Mercury's surface, there are what are called hydroxyls, small combinations of oxygen and hydrogen atoms. And so, when the solar wind, containing positively charged protons, bombards the planet, protons reach Mercury's soil and interact with hydroxyl groups.

[00:08:01]This interaction passes energy to hydroxyls, making them collide into each other.

[00:08:06]And, as a result, water is generated.

[00:08:11]Mercury also has a tiny atmosphere, which is basically a bubble of particles around a celestial body held by its gravity.

[00:08:18]Since the first planet from the sun is quite small, its gravity isn't that strong. So, it doesn't hold on to its atmosphere as effectively as the Earth.

[00:08:27]This could be the reason why Mercury's atmosphere doesn't stay in one place, moving around the planet, appearing and disappearing over different regions.

[00:08:35]The composition of Mercury's atmosphere differs from that we have on Earth. It's mostly made up of metals, like the very soft, silvery-white metal sodium.

[00:08:45]Some scientists think that atmosphere on this planet is caused by magnetic tornadoes, where the solar wind particles strike Mercury's surface, pulling atoms up, while gravity drags them in the opposite direction.

[00:08:57]The same happens to the water molecules forming on Mercury. Although some of them break down because of the solar radiation and others escape into space, a small amount make it into the planet's poles, where they find a safe shadowy craters. The lack of substantial atmosphere means there's no heat transfer throughout the planet. So, once in craters, water molecules don't evaporate.

[00:09:21]Scientists have calculated that within the next 3 million years, this process would generate approximately 11 trillion tons of water ice on Mercury.

[00:09:31]So, what happens to those water molecules drifting away into space?

[00:09:35]Particles that are sent into space as a result of the solar wind pulled from a comet-like tail behind Mercury, about 15 million miles long. The tail consists of numerous particles, but it's sodium atoms that make it visible as they are better at scattering yellow light coming from the Sun.

[00:09:52]Scientists can then observe this tail on long exposure images.

[00:09:57]If you stood on the planet's equator at midnight, you'd notice a yellowish glow close to the horizon in all directions.

[00:10:05]Mercury's tail is a bizarre feature, but it's not the only one. It has a truly alien landscape with formations never before seen on other planets.

[00:10:15]These geological features blanketing the planet's surface are called dents or hollows. They form when volatile material within Mercury evaporates.

[00:10:25]It comes from inside the planet, turns from solid into vapor, breaks through its surface, leaving behind specific marks similar to those seen in volcanic eruptions. Scientists believe these geological features are a fairly recent activity on Mercury, and they're not sure what kind of volatile material causes these dents surrounded by bright, often bluish halos.

[00:10:47]From observations, researchers have noticed that the hollows usually begin as darkening of the surface.

[00:10:53]Later on in their formation, the middle part of these areas start to collapse, and the edges develop a peculiar brightening. With time, the processes that led to these geological formations seem to wear off.

[00:11:05]The landforms become smooth, and solar wind erodes the surface till these dents disappear completely.

[00:11:12]Today, Mercury is a barren world devoid of all the crucial ingredients for life, but it might not have always been like that. Scientists believe that volatiles, or chemical elements that turn into gas at low temperatures, such as water, are crucial for life.

[00:11:28]In the past, it was believed that Mercury's cracked [music] terrain was caused by strong quakes followed by asteroid impacts. But, a recent study suggests that this fractured landscape might be due to these [music] volatile chemicals. When heated by magma, they transform into gases causing the ground above them to collapse.

[00:11:48]Billions of years ago, there could have been large amounts of volatiles underneath Mercury's [music] surface.

[00:11:53]And although the planet has drastic temperature fluctuations on its surface, just below it, the environment would be suitable, at least for some life forms.

[00:12:02]If one of those chemicals was in fact water, life had a chance at forming and surviving underneath the planet's surface.

[00:12:10]But, even the probability of water existing on such an inhospitable planet would be a significant revelation for the search for life and potentially habitable worlds in the Milky Way. And we may need to step up our search efforts as Mercury could pose a threat to us.

[00:12:27]The innermost planet has the most elliptical orbits among all the planets in our solar system. Scientists ran computer simulations and the result suggests that within a few billion years, Mercury's orbit could further elongate. When influenced by the gravitational forces of the outer giant planets, Mercury's unpredictable path could potentially disrupt the orbits of the inner planets.

[00:12:50]Out of 2,500 simulations, five scenarios showed Mars could be ejected from the solar system and in about 200 cases, two solar space bodies would collide with one of them potentially being the Earth.

[00:13:04]But, don't be afraid. Even if this were to happen, it wouldn't be anytime soon.

[00:13:09]And right now, scientists are trying to learn more about our mysterious neighbor.

[00:13:14]However, Mercury is an extremely challenging planet to visit all because of its intricate location. The Sun doesn't only blast the planet with intense heat 10 times as strong as on Earth, but it also exerts a strong gravitational pull on any approaching spacecraft, speeding them as they get closer.

[00:13:32]All this means that the probes we sent have to be larger, equipped with scientific instruments and protective shields, and on top of that, they have to carry tons and tons of fuel to counteract the gravitational attraction of the Sun. To compare, scientists think it would take less fuel for a spacecraft to reach Pluto.

[00:13:53]Mariner 10 had to fly around Venus to slow down, and it still didn't enter the orbit around Mercury directly. Even missions to distant Jupiter and Saturn preceded close exploration of Mercury.

[00:14:04]About 40 years after the Mariner 10 mission, the MESSENGER probe required several gravity assist maneuvers and a few years to get into orbit around Mercury. In total, the probe has covered an astonishing distance of 4.9 billion miles, which is more than traveling to Uranus and back.

[00:14:24]Observing the planet from Earth is just as challenging. Mercury is too close to the Sun, and the two celestial bodies rise and set almost simultaneously in our sky. So, astronomers have short windows just before sunrise and after sunset to look at the tiny innermost planet. And using telescopes to glance at Mercury during daytime, scientists risk damaging the telescope's optics because of how intense solar radiation is.

[00:14:50]But scientists haven't given up. If successful, the mission named Bepi Colombo will be the third time we study Mercury from up close. In late 2025, two space probes will make several flybys of the planet and perhaps reveal even more of its mysteries.

[00:15:08]What do you think that probe is going to find? And is it possible we might discover signs of past life in the most unexpected place of the solar system?

[00:15:17]Let us know what you think in the comments below. We read them all. And make sure to stay tuned here for more exciting discoveries in the universe.

[00:15:26]Thanks for watching.