Eryn Cangi, University of Colorado Boulder

Today, the atmosphere of our neighbor planet Venus is as hot as a pizza oven and drier than the driest desert on Earth – but it wasn't always that way.

Billions of years ago, Venus had as much water as Earth does today. If that water was ever liquid, Venus may have once been habitable.

Over time, that water has nearly all been lost. Figuring out how, when and why Venus lost its water helps planetary scientists like me understand what makes a planet habitable — or what can make a habitable planet transform into an uninhabitable world.

Scientists have theories explaining why most of that water disappeared, but more water has disappeared than they predicted.

In a May 2024 study, my colleagues and I revealed a new water removal process that has gone unnoticed for decades, but could explain this water loss mystery.

Energy balance and early loss of water

The solar system has a habitable zone – a narrow ring around the Sun in which planets can have liquid water on their surface. Earth is in the middle, Mars is outside on the too-cold side, and Venus is outside on the too-hot side. Where a planet sits on this habitability spectrum depends on how much energy the planet gets from the Sun, as well as how much energy the planet radiates away.

The theory of how most of Venus' water loss occurred is tied to this energy balance. On early Venus, sunlight broke up water in its atmosphere into hydrogen and oxygen. Atmospheric hydrogen heats up a planet — like having too many blankets on the bed in summer.

When the planet gets too hot, it throws off the blanket: the hydrogen escapes in a flow out to space, a process called hydrodynamic escape. This process removed one of the key ingredients for water from Venus. It's not known exactly when this process occurred, but it was likely within the first billion years or so.

Hydrodynamic escape stopped after most hydrogen was removed, but a little bit of hydrogen was left behind. It's like dumping out a water bottle – there will still be a few drops left at the bottom. These leftover drops can't escape in the same way. There must be some other process still at work on Venus that continues to remove hydrogen.

Little reactions can make a big difference

Our new study reveals that an overlooked chemical reaction in Venus' atmosphere can produce enough escaping hydrogen to close the gap between the expected and observed water loss.

Here's how it works. In the atmosphere, gaseous HCO⁺ molecules, which are made up of one atom each of hydrogen, carbon and oxygen and have a positive charge, combine with negatively charged electrons, since opposites attract.

But when the HCO⁺ and the electrons react, the HCO⁺ breaks up into a neutral carbon monoxide molecule, CO, and a hydrogen atom, H. This process energizes the hydrogen atom, which can then exceed the planet's escape velocity and escape to space. The whole reaction is called HCO⁺ dissociative recombination, but we like to call it DR for short.

Water is the original source of hydrogen on Venus, so DR effectively dries out the planet. DR has likely happened throughout the history of Venus, and our work shows it probably still continues into the present day. It doubles the amount of hydrogen escape previously calculated by planetary scientists, upending our understanding of present-day hydrogen escape on Venus.

Understanding Venus with data, models and Mars

To study DR on Venus we used both computer modeling and data analysis.

The modeling actually began as a Mars project. My Ph.D. research involved exploring what sort of conditions made planets habitable for life. Mars also used to have water, though less than Venus, and also lost most of it to space.

To understand martian hydrogen escape, I developed a computational model of the Mars atmosphere that simulates Mars' atmospheric chemistry. Despite being very different planets, Mars and Venus actually have similar upper atmospheres, so my colleagues and I were able to extend the model to Venus.

We found that HCO⁺ dissociative recombination produces lots of escaping hydrogen in both planets' atmospheres, which agreed with measurements taken by the Mars Atmosphere and Volatile EvolutioN, or MAVEN, mission, a satellite orbiting Mars.

Having data collected in Venus' atmosphere to back up the model would be valuable, but previous missions to Venus haven't measured HCO⁺ – not because it's not there, but because they weren't designed to detect it. They did, however, measure the reactants that produce HCO⁺ in Venus' atmosphere.

By analyzing measurements made by Pioneer Venus, a combination orbiter and probe mission that studied Venus from 1978-1992, and using our knowledge of chemistry, we demonstrated that HCO⁺ should be present in the atmosphere in similar amounts to our model.

Follow the water

Our work has filled in a piece of the puzzle of how water is lost from planets, which affects how habitable a planet is for life. We've learned that water loss happens not just in one fell swoop, but over time through a combination of methods.

Faster hydrogen loss today via DR means that less time is required overall to remove the remaining water from Venus. This means that if oceans were ever present on early Venus, they could have been present for longer than scientists thought before water loss through hydrodynamic escape and DR started. This would provide more time for possible life to arise. Our results don't mean oceans or life were definitely present, though – answering that question will require lots more science over many years.

There is also a need for new Venus missions and observations. Future Venus missions will provide some atmospheric measurements, but they won't focus on the upper atmosphere where most HCO⁺ dissociative recombination takes place. A future Venus upper atmosphere mission, similar to the MAVEN mission at Mars, could vastly expand everyone's knowledge of how terrestrial planets' atmospheres form and evolve over time.

With the technological advancements of recent decades and a flourishing new interest in Venus, now is an excellent time to turn our eyes toward Earth's sister planet.

Eryn Cangi, Research Scientist in Astrophysical & Planetary Sciences, University of Colorado Boulder

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Jennifer Robinson, Auburn University

Curious Kids is a series for children of all ages. If you have a question you'd like an expert to answer, send it to curiouskidsus@theconversation.com.

How does the brain think? – Tom, age 16, San Diego, California

Have you ever wondered how your brain creates thoughts or why something randomly popped into your head? It may seem like magic – but actually the brain is like a supercomputer inside your head that helps you think, learn and make decisions.

Imagine your brain as a busy city with lots of streets and buildings. Each part of the brain has a specific job to do, just like certain areas of a city or certain buildings serve different purposes. When you have a thought, it's like a message traveling through the city, passing from one area to another.

As a professor of psychology and neuroscience, I have studied the brain for almost 20 years. Neurologists, neuroscientists and neurosurgeons work every day to understand the brain better. And there's still a lot to learn.

Practice and repetition create skills

The neuron is a key player in the brain – these are tiny cells that send and receive signals and messages so they can communicate with each other.

Your brain has somewhere between 80 billion and 100 billion neurons. Neurons tend to group together to form neural tracts, which would be like the streets and highways in the city analogy. When you have a thought, neurons in your brain fire up and create electrical impulses. These impulses tend to travel along similar pathways and release tiny chemicals called neurotransmitters along the way.

These neurotransmitters are like the construction crew that builds the roads, making it easier for the messages to be delivered. You can imagine it as a dirt road, but as more traffic – that is, neuron signals – travel the dirt road, the road gets upgraded to a paved street. If the traffic continues, it gets upgraded to a highway.

As you learn new things and experience the world around you, these connections grow stronger. For example, when you are learning to ride a bike, you may be unsteady and find it hard to coordinate all of the different muscles along with your ability to balance. But the more you practice, the more the neurons controlling your muscles and your ability to balance fire together, which makes it much easier as you practice. Neurons are wiring together and forming neural networks.

That's why practice and repetition are important for improving your skills, whether playing the piano or learning a language. Neural networks are created and then strengthened the more times they communicate together. Scientists have a saying in this field: “Neurons that fire together wire together.” Certain thinking or behavior patterns can be chalked up to this kind of repeated synchronized activity.

Developing creativity

You are conscious of only a very small portion of the information your brain takes in. It is constantly receiving input from your senses – sights, sounds, tastes, smells and touch. When you see a cute puppy or hear your favorite song, your senses send signals to the brain, triggering a chain reaction of thoughts and emotions.

The brain also stores memories, which are like files in a computer that you can access whenever you need them. Memories help shape your thoughts and influence how you see the world.

If you remember a fun day at the beach, it might make you feel happy and relaxed. If you smell an apple pie, it may remind you of your grandma's baking. These thoughts are triggered because these pleasant associations have been formed in your brain, and through repetition, strengthened over time.

Creativity is another superpower of the brain. When you let your imagination run wild, your brain can come up with new ideas, stories and inventions. Artists, writers and scientists all use their creative brains to explore new possibilities and solve problems.

Have you ever experienced a “eureka” moment when a brilliant idea pops into your head out of nowhere? That's your brain's way of connecting the dots and coming up with a solution.

Keeping your brain healthy

Most scientists agree that sleep is really important for your brain to process information from the day and to allow it to rest and form new connections. A lot of people find that they have new ideas or thoughts after a good night's sleep. The opposite is true, too – without enough sleep, you may feel like you can't think straight.

Along with enough sleep, eat healthy foods and exercise. Just like a car needs fuel to run smoothly, your brain needs nutrients and oxygen to function at its best and to boost your thinking power.

Activities that challenge you are also great: reading, doing puzzles, playing music, making art, doing math, writing essays and book reports and journaling. Positive thinking also helps. Keep in mind that whatever you are consuming – what you're eating or what you're watching, listening to or reading – has the power to influence your brain.

Conversely, smoking cigarettes, vaping, drinking alcohol and using drugs kills brain cells. So might head injuries that can occur when playing sports such as football, soccer and bicycling – but wearing a helmet can make a big difference.

The brain is a fascinating organ that works tirelessly to create thoughts, memories and ideas. As technology continues to improve, scientists will learn more and more about how biological processes give rise to our conscious experiences. The challenges of learning about the brain are like a neuroscientific moonshot – we have a long way to go before we completely understand how it works.

Hello, curious kids! Do you have a question you'd like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you're wondering, too. We won't be able to answer every question, but we will do our best.

Jennifer Robinson, Professor of Psychology, Auburn University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Todd M. Freeberg, University of Tennessee

Animal behavior research relies on careful observation of animals. Researchers might spend months in a jungle habitat watching tropical birds mate and raise their young. They might track the rates of physical contact in cattle herds of different densities. Or they could record the sounds whales make as they migrate through the ocean.

Animal behavior research can provide fundamental insights into the natural processes that affect ecosystems around the globe, as well as into our own human minds and behavior.

I study animal behavior – and also the research reported by scientists in my field. One of the challenges of this kind of science is making sure our own assumptions don't influence what we think we see in animal subjects. Like all people, how scientists see the world is shaped by biases and expectations, which can affect how data is recorded and reported. For instance, scientists who live in a society with strict gender roles for women and men might interpret things they see animals doing as reflecting those same divisions.

The scientific process corrects for such mistakes over time, but scientists have quicker methods at their disposal to minimize potential observer bias. Animal behavior scientists haven't always used these methods – but that's changing. A new study confirms that, over the past decade, studies increasingly adhere to the rigorous best practices that can minimize potential biases in animal behavior research.

Biases and self-fulfilling prophecies

A German horse named Clever Hans is widely known in the history of animal behavior as a classic example of unconscious bias leading to a false result.

Around the turn of the 20th century, Clever Hans was purported to be able to do math. For example, in response to his owner's prompt “3 + 5,” Clever Hans would tap his hoof eight times. His owner would then reward him with his favorite vegetables. Initial observers reported that the horse's abilities were legitimate and that his owner was not being deceptive.

However, careful analysis by a young scientist named Oskar Pfungst revealed that if the horse could not see his owner, he couldn't answer correctly. So while Clever Hans was not good at math, he was incredibly good at observing his owner's subtle and unconscious cues that gave the math answers away.

In the 1960s, researchers asked human study participants to code the learning ability of rats. Participants were told their rats had been artificially selected over many generations to be either “bright” or “dull” learners. Over several weeks, the participants ran their rats through eight different learning experiments.

In seven out of the eight experiments, the human participants ranked the “bright” rats as being better learners than the “dull” rats when, in reality, the researchers had randomly picked rats from their breeding colony. Bias led the human participants to see what they thought they should see.

Eliminating bias

Given the clear potential for human biases to skew scientific results, textbooks on animal behavior research methods from the 1980s onward have implored researchers to verify their work using at least one of two commonsense methods.

One is making sure the researcher observing the behavior does not know if the subject comes from one study group or the other. For example, a researcher would measure a cricket's behavior without knowing if it came from the experimental or control group.

The other best practice is utilizing a second researcher, who has fresh eyes and no knowledge of the data, to observe the behavior and code the data. For example, while analyzing a video file, I count chickadees taking seeds from a feeder 15 times. Later, a second independent observer counts the same number.

Yet these methods to minimize possible biases are often not employed by researchers in animal behavior, perhaps because these best practices take more time and effort.

In 2012, my colleagues and I reviewed nearly 1,000 articles published in five leading animal behavior journals between 1970 and 2010 to see how many reported these methods to minimize potential bias. Less than 10% did so. By contrast, the journal Infancy, which focuses on human infant behavior, was far more rigorous: Over 80% of its articles reported using methods to avoid bias.

It's a problem not just confined to my field. A 2015 review of published articles in the life sciences found that blind protocols are uncommon. It also found that studies using blind methods detected smaller differences between the key groups being observed compared to studies that didn't use blind methods, suggesting potential biases led to more notable results.

In the years after we published our article, it was cited regularly and we wondered if there had been any improvement in the field. So, we recently reviewed 40 articles from each of the same five journals for the year 2020.

We found the rate of papers that reported controlling for bias improved in all five journals, from under 10% in our 2012 article to just over 50% in our new review. These rates of reporting still lag behind the journal Infancy, however, which was 95% in 2020.

All in all, things are looking up, but the animal behavior field can still do better. Practically, with increasingly more portable and affordable audio and video recording technology, it's getting easier to carry out methods that minimize potential biases. The more the field of animal behavior sticks with these best practices, the stronger the foundation of knowledge and public trust in this science will become.

Todd M. Freeberg, Professor and Associate Head of Psychology, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.