Hi, I’m Emily from MinuteEarth. When you look at Earth from space, it appears mostly blue, with some green, white, and brown. This blue color is because Earth is the only planet we know of that has liquid water covering its surface. Let’s explore why Earth’s water is so special and where it came from.
Earth’s surface is about 70% water, which is unusual compared to other planets in our solar system. When our solar system formed, it was too hot for ice to exist near the young Sun. Any water vapor would have been blown away by the solar wind. So, how did Earth get its water?
Water couldn’t have been created on Earth over time because natural processes like breathing and photosynthesis create and destroy water in equal amounts. This means Earth’s water must have come from somewhere else, likely from space. Scientists believe that meteorites called “Carbonaceous Chondrites” brought water to Earth. These meteorites contain water and carbon and have a similar hydrogen composition to Earth’s water, suggesting they are the source of our oceans and rivers.
Clouds are fascinating! They form when solar energy evaporates water from the Earth’s surface. This water vapor rises into the sky, where it cools and condenses into tiny droplets, forming clouds. Cumulus clouds, for example, have flat bottoms because the water vapor condenses at the same altitude, creating a uniform base.
As water vapor condenses, it releases energy, which heats the surrounding air and helps the cloud grow. This process can create towering clouds and even storms if there’s enough water vapor.
Have you ever noticed how rivers twist and turn? This happens because of small disturbances and the soft soil on the plains. When a riverbank erodes, the water flows faster in that area, creating a bend. Over time, these bends become more pronounced, forming a meandering pattern.
Interestingly, the length of one S-shaped bend in a river is usually about six times the width of the river. This pattern is consistent in rivers worldwide. Sometimes, these bends can loop back on themselves, creating a crescent-shaped lake called an “oxbow lake.”
On Mars, scientists have found evidence of ancient river channels. However, some of these channels appear raised above the surrounding landscape, which is unusual. This phenomenon is called “inverted relief.” It happens when the riverbed becomes harder than the surrounding rock, and erosion removes the softer material, leaving the riverbed elevated.
Studying these features on Mars helps scientists understand the planet’s history and the role water played in shaping its surface.
Explore these fascinating features on Google Earth, and enjoy learning about the wonders of water on Earth and beyond!
Build a simple model of the water cycle using a clear plastic container, some soil, a small cup of water, and plastic wrap. Observe how water evaporates, condenses, and precipitates. Write a short paragraph explaining each stage of the water cycle and how it relates to cloud formation.
Research Carbonaceous Chondrites and their role in bringing water to Earth. Create a poster or digital presentation that explains how these meteorites contributed to Earth’s water supply. Include images and interesting facts to make your presentation engaging.
Use a sandbox or a large tray filled with sand to simulate river meandering. Pour water at one end and observe how the water creates bends and curves. Record your observations and explain why rivers meander and how oxbow lakes are formed.
Use Google Earth to explore Mars and locate inverted river channels. Write a short report on how these features were formed and what they tell us about Mars’ history. Include screenshots and descriptions of the areas you explored.
Keep a cloud observation journal for a week. Each day, note the types of clouds you see, their shapes, and any weather changes. At the end of the week, analyze your observations and write a summary of how clouds form and their impact on weather patterns.
Sure! Here’s a sanitized version of the transcript:
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Hi, I am Emily from MinuteEarth. From a distance, the world looks blue, green, white, and kind of yellowish-brown. But from a greater distance, it appears just blue, which makes it unique. It’s the only planet we know of that is covered in liquid water. Coming up are four short videos about the uniqueness of Earth’s water. Let’s dive in with the question: “Where did it all come from?”
Unlike every other planet in our solar system, Earth’s surface is 70% liquid water. While this is essential for life, it is also quite unusual. Everything we know about how and when our planet formed suggests that Earth’s surface should be bone dry. The story goes like this: Our solar system formed from the collapse of a large cloud of dust and gas. The dense blob of gas at the center ignited to form the Sun, which, as a young unstable star, unleashed a fierce solar wind. Over time, this stream of charged particles pushed the remaining gas cloud farther out, leaving only solid particles behind to clump together into rocks, planetesimals, and finally, the rocky planets of the inner solar system.
Here’s the problem: water in the form of ice couldn’t have been one of the solid particles that formed our planet because the early inner solar system was far too hot for frozen water, and any water vapor would have been blown away by the solar wind. So, if Earth didn’t start off with water, how did we end up with such magnificent oceans? We know H2O wasn’t created here over time because natural processes like combustion, breathing, and photosynthesis create and destroy roughly equal amounts of water. The amounts involved are so small that they can’t account for the abundance of water on the planet.
Since Earth’s water was neither part of the original package nor created here, it must have come from far away—on meteoroids, comets, or other bodies originating in the outer solar system, where it was cold enough for frozen water to survive. The icy bodies we call “comets” are a logical candidate for the source of our water, but they were ruled out when we discovered they contained more heavy hydrogen than Earth’s water. Heavy hydrogen has a neutron as well as a proton in its nucleus. For every million hydrogen atoms in Earth’s water, about 150 are heavy ones, while typical comet water has twice that many. These mismatched chemical signatures suggest that Earth’s water couldn’t have arrived on comets.
It turns out that the most likely source for Earth’s water is a type of meteorite called the “Carbonaceous Chondrite.” “Chondrite” is a name given to the class of stony meteoroids that most commonly strike the Earth, but only the Carbonaceous Chondrite contains water and lots of carbon, as the name suggests. They have water in them because they form beyond the Sun’s Frost Line, and their water has heavy levels of hydrogen similar to that of Earth’s water. This strongly suggests that these meteorites are the source of our ice caps, clouds, rivers, and oceans. Thus, the water that turned our planet into a blue marble came quite literally from the cosmos.
Now, speaking of the sky, many clouds up there have a flat bottom and a shape that seems peculiar. Why do they have that shape? If we wanted to create a cloud from scratch, we would need a fleet of jumbo jets or several hundred hot air balloons to carry hundreds of tons of water up to the sky. Then, we would need to disperse all that liquid into tiny droplets small enough to float. In short, it wouldn’t be easy. Yet, our atmosphere manages to produce clouds all over the world at altitudes of up to 20 kilometers above sea level using water and energy from Earth’s surface.
Cumulus clouds, for example, begin when solar energy evaporates water from oceans, plants, and soil. As the patch of air above collects moisture and heat, cooler, heavier air sinks around it, pinching it off and pushing it upward like an invisible hot air balloon. Surprisingly, this balloon’s cargo doesn’t weigh it down. In fact, the more water vapor it collects before lift-off, the lighter it gets. This is because water vapor is a gas, just like the nitrogen and oxygen that make up most of the atmosphere. Basic physics dictates that a given volume of gas has the same number of molecules regardless of what those molecules are.
As the invisible balloon rises, the falling pressure outside allows it to expand, spreading out its internal heat and lowering its temperature. Eventually, the air at the top cools enough for the water vapor to condense into droplets, which appear from afar as a thin wisp of cloud. As the rest of the balloon rises, water vapor continues to cool and condense at the same altitude, creating a flat-bottomed cloud that seems to grow upward out of nothing.
Moreover, as the condensing water vapor molecules bond together into liquid droplets, they release the energy they absorbed from Earth’s surface when they evaporated. This heats the surrounding pocket of air, giving it lift and drawing more moist air up behind it. Even in a small cumulus cloud, the total energy released from condensation is enormous—equivalent to about 270 tons of TNT. If the supply of water vapor is much larger, the energy released can produce towering clouds with violent updrafts, fierce electrical storms, and large hailstones.
If you’ve ever been up in a hot air balloon or a plane and looked down at Earth, you may have noticed that many rivers look quite meandering. Compared to the white-water streams that tumble down mountainsides, the rivers of the plains may seem calm and lazy. Mountain streams are confined by the steep walls of the valleys they carve, while on the open plains, those stony walls give way to soft soil, allowing rivers to shift their banks and set their own ever-changing courses to the sea.
These courses rarely run straight for long because all it takes to turn a straight stretch of river into a bendy one is a little disturbance and a lot of time. For example, if a muskrat burrows a den in one bank of a stream, her tunnels weaken the bank, which eventually begins to crumble into the stream. Water rushes into the newly formed hollow, sweeping away loose dirt and making the hollow even deeper. This allows the water to flow faster and carry away more dirt, and so on.
As more of the stream’s flow is diverted into the deepening hole on one bank, the flow on the other side weakens and slows. Since slow-moving water can’t carry the sand-sized particles that fast-moving water can, the dirt settles to the bottom, making that area shallower and slower. This accumulation continues until it creates new land on the inside bank. Meanwhile, the fast-moving water near the outside bank sweeps out of the curve with enough momentum to carry it across the channel, carving another curve, and then another, and so on.
The wider the stream, the longer it takes for the current to reach the other side, and the greater the distance downstream to the next curve. Measurements of meandering streams worldwide reveal a regular pattern: the length of one S-shaped meander tends to be about six times the width of the channel. Thus, tiny meandering streams resemble miniature versions of their larger counterparts. As long as nothing obstructs a river’s meandering, its curves will continue to grow until they loop around and connect with themselves. When that happens, the river’s channel follows the straighter path downhill, leaving behind a crescent-shaped remnant called an “oxbow lake.”
We have many names for these lakes, as they can occur wherever liquid flows or used to flow. This raises an interesting question: What do Martians call them?
In a recent video, we discussed a photo of the surface of Mars that features an ancient stream channel, indicating that liquid water once flowed there. However, a nearby crater casts a shadow, suggesting that the light in the image comes from a specific angle, which makes it seem like the stream channel is raised above the surrounding landscape. This contradicts the basic fact that river channels should be valleys since they have been carved into the ground.
It turns out that this stream channel is an example of a geological process that creates “inverted relief.” In cold climates, you may have seen something similar with compacted footprints in the snow, where the surrounding snow melts away, leaving the footprints sticking out. The same can happen to a river valley. For instance, if a stream running through a desert dries up due to lack of rain, groundwater can be drawn upward by capillary action. As it rises and evaporates, dissolved minerals are left behind, cementing the sediments at the riverbed.
Over time, as the stream dries up repeatedly, more cementing accumulates, making the riverbed harder and more resistant to erosion than the surrounding rock. Eventually, wind erodes the softer rock, turning the channel into an inverted version of its former self. We can’t know exactly how this riverbed got turned inside out without further investigation, but we can make educated guesses by studying inverted relief on our planet. You could even find examples on Google Earth, but be warned that figuring out what’s right side up and upside down can be quite confusing.
Enjoy your exploration of Google Earth, and thanks for watching!
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This version maintains the content while removing any informal language or unnecessary details.
Water – A liquid that is essential for life on Earth and covers most of the planet’s surface. – Water is crucial for all living organisms and plays a key role in weather patterns and climate.
Earth – The third planet from the Sun, home to diverse ecosystems and life forms. – Earth is the only known planet in our solar system that supports life.
Clouds – Collections of tiny water droplets or ice crystals suspended in the atmosphere. – Clouds can affect weather by blocking sunlight and bringing rain or snow.
Rivers – Large natural streams of water flowing towards oceans, seas, or lakes. – Rivers are important for transporting nutrients and providing habitats for many species.
Solar – Related to or derived from the Sun. – Solar energy is harnessed using solar panels to generate electricity.
Energy – The ability to do work or cause change, existing in various forms such as kinetic or potential. – Energy from the Sun drives the water cycle and influences Earth’s climate.
Meteorites – Fragments of rock or metal from space that survive their passage through Earth’s atmosphere and land on the surface. – Scientists study meteorites to learn more about the early solar system.
Evaporation – The process by which water changes from a liquid to a gas or vapor. – Evaporation from oceans and lakes is a key part of the water cycle.
Meander – A winding curve or bend in a river or stream. – The river’s meander creates a unique landscape and provides diverse habitats for wildlife.
Space – The vast, seemingly infinite expanse that exists beyond Earth’s atmosphere. – Space exploration helps us understand more about our universe and the potential for life beyond Earth.
