Monthly Archives: October 2015

DIY Water Bending

Electricity is everywhere! That isn’t a joke. Electricity is simply the movement of electrons. Electrons are found in atoms which make up all of the molecules in our bodies, and don’t like to stand still. Electricity can be tricky to describe and understand, but most of us have felt it in some way. Have you ever shuffled across the carpet in your socks and run over to one of your friends (or siblings!) in the hopes of giving them a tiny shock? That’s exactly what’s happening in this video!


To see what’s going on, let’s delve into the miniature world of atoms. An atom is made up of three kinds of building blocks: protons, neutrons, and electrons. In an atom, the protons and neutrons live in the center, or the nucleus. Whizzing around the nucleus are tiny electrons.

Subatomic particles interact via something called a “charge”. A charge can be either positive (+), negative (-), or neutral (0). Neutral objects don’t have a charge, and don’t interact with other charges. They just hang out. When it comes to charges, opposites attract: positive and negative charges are always pulled towards each other. When like charges get together, they repel, or push each other apart. If too many like charges gather in the same place, the repulsion is so strong that some electrons will jump away, making lightning!


Electrons are very easy to move around. They’re so tiny that you can’t see them, and almost impossibly light. In some materials with thin fibers, like textiles or human hair, the electrons aren’t very securely attached to their atoms. When a balloon is rubbed against someone’s hair or clothing (or socks on the carpet), bunches of electrons are transferred to the balloon.

Water molecules are polar, meaning they have a negative side and a positive side. When a stream of water is brought close to the electron-laden (thus negatively charged) balloon, the negative ends of the water molecules are pushed away, and their positive ends come closer to the negative charge on the balloon. What do these opposite charges do? Attract!


Thomas Edison and the Bright Idea

Thomas Edison famously invented the incandescent light bulb. These light bulbs are pretty simple things. They are really just a glass casing around a tiny metal resistor called the filament. As electricity runs through it, the filament heats up until it produces light. But how much does it have to heat up? It turns out to be a pretty interesting question.

Britannica Light Bulb

Incandescent light bulb. The filament is the horizontal piece in the center of the bulb. Image credit: Encyclopædia Britannica

Everything gives off light based on its temperature, but not all light is the kind we can see. That part, known as the visible spectrum, is a tiny part of the larger electromagnetic spectrum. These different kinds of light are separated by their energies, which can be described with wavelength.


Where is a simple equation that allows us to find out what wavelength is given off by an object at a given temperature. It’s called Wien’s Displacement Law.

Screen Shot 2015-10-21 at 2.10.42 PM

Humans are about 90 degrees Fahrenheit, which is about 305K. To find the wavelength emitted by humans, all we have to do is divide .002898 by 305. This gives about 9500 nanometers (nm) which is what we measure wavelength in for visible light. Visible light is between 400nm and 700nm, so 9500nm is pretty far away from that. This puts it squarely in the infrared.


The full electromagnetic spectrum, including the very small visible light portion. Credit NASA

So how hot does that filament need to be to give off visible light? Lets aim for 500nm, which is definitely in the visible light range. By using algebra, Wien’s Displacement Law can be rearranged to T=b/. Dividing b by 500nm gives a temperature of 9973℉, which is about the temperature of the surface of the sun!

This actually makes total sense too! This means that the sun’s primary light emission is smack dab in the middle of our visible spectrum. It definitely makes sense that if we were to gain the ability to see, it would be to see the kind of light that was the most common. However, pretty much everything in the sun is a plasma due to the immense heat. There is no way that a light bulb could survive such insane temperatures.

Light bulb filament comes in at a relatively cool to the sun but still insanely hot 4500℉. Throwing this back into the equation, we get 1052nm, which is much closer to the 400nm to 700nm range. The primary emission is still in the infrared. However, this only gives the peak wavelength of light given off. The actual light is a mix of light more like this:

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For a light bulb, only about 5% of the energy is given off as light that we can see. The rest of it is mostly given off as infrared light, or heat which is why these bulbs feel hot. The reason they don’t feel like 4500℉ is that the inside of the light bulb is a vacuum–meaning it contains no air–and the heat thankfully doesn’t conduct through it very well. They actually use this vacuum insulation for water bottles, thermoses, and even the Dewars that hold things like liquid nitrogen!

This inefficiency is the reason behind moving to much more eco-friendly fluorescent light bulbs. These bulbs don’t use Wien’s Displacement Law to produce light, but instead are filled with atoms that naturally release light when hit with a bit of electricity. Even many new bulbs that look like incandescent bulbs actually contain several small Light Emitting Diodes, or LED’s inside which share the energy efficient qualities of fluorescent bulbs. What a bright idea!

LED Bulb

Geyser in a Bottle! Science!!!

Ever wish you could control the weather? In this experiment, we’ll harness the weight of the atmosphere to make a tiny storm in a beaker! As you read this sentence, the air around you is exerting enormous pressure on your body. Imagine a jacket made of one-inch checkerboard squares. Now imagine that each tiny box weighs fifteen pounds! At sea level, atmospheric pressure is about 15 pounds per square inch. Multiply 15 by the number of square inches on the surface of your body to get an idea of how much weight you’re bearing every moment of every day.


Atmospheric pressure results from the weight of the air above you. Credit: Peter Mulroy,

We don’t notice all this weight because we’re used to it. Take the pressure away, though, and awesome dynamics ensue. Heating a volume of air is one way to create a drop in pressure. Adding heat to a gas causes its molecules to speed up and spread out.


As the air inside the flask expands, some is pushed out through the tube. Invert the container into cool water and the liquid blocks the opening– the escaped air is trapped outside! The gas left inside the flask shrinks as it cools, creating a low-pressure zone in the container. Here’s where that 15 pounds per square inch comes in. Once the pressure in the flask is lowered, atmospheric pressure pushing on the surface of the water outside forces the liquid up the tube.

When the water reaches the main compartment of the container, the gas inside experiences a sudden drop in temperature. A chain reaction of cooling occurs, and water rushes in to fill the empty space left by the condensing air.

#WhySpaceMatters: The Next Martian

Space simulations are a big part of the AstroCamp experience, and they’re more relevant now than ever. #whyspacematters

“Exploration enables science and science enables exploration.” This is one of the seven pioneering principles of NASA’s game plan for Martian exploration, released to the public last week. The technology required for interplanetary colonization is in the works– and entering the mainstream. Thanks to collaboration between NASA’s Jet Propulsion Laboratory and the production team behind The Martian, everyday people are enjoying unprecedented exposure to honest rocket science. Charles Elachi, director of JPL, describes the film as a “reasonable representation” of what’s to come, and with good cause.

Ion propulsion is already a reality. The Deep Space Network has maintained communications with spaceships far more distant than Mars for decades. Precision landing technology capable of planting a MAV-like spacecraft in a habitable location years ahead of its human crew is on the way, as is an autonomous system for synthesizing rocket fuel from local ingredients. SpaceX and NASA are independently building long-distance spacecraft; both have passed recent key flight tests and continue to inch closer to readiness.


Ion engines like the NASA Evolutionary Xenon Thruster (NEXT), shown here, made history by propelling the Dawn mission to dwarf planets Vesta and Ceres.

The hardware and software are developing swimmingly, but it’s more than that. Humanity is gearing up to step outward.

Phase one: spacefaring Earth does its homework. Astronaut scientists explore what happens to the human body when it goes without gravity for many months at a time. They grow lettuce outside our planet’s atmosphere, experiment with advanced fire safety, and test the long-term life support systems that will eventually shepherd our species far from home. This phase has been under way for years. So far, it’s a monumental success.

Phase two: the proving ground. Current space activity takes place in low Earth orbit (LEO). Mars is several months’ journey away. Before committing a crewed ship to such an odyssey, NASA plans to train and troubleshoot in a middle-ground zone– the space around the moon. This region will host early versions of deep-space habitats and other interplanetary technology.

The proving ground phase also features an unmanned mission to capture a small asteroid and put it into lunar orbit, where it will be explored and analyzed by tethered humans as extravehicular activity practice. That’s right… the moon will have a mini-me!

Finally, phase three: Earth independence. It’s a true pioneering endeavor, one that has galvanized some of the brightest problem-solving minds of recent generations. Human footprints on Mars may be a busy few decades away, but the steps between here and there are clear and surmountable.


Campers practice interplanetary exploration in the Mars: Valles Marineris simulation. Valles Marineris, the largest known canyon in the solar system, would stretch from Los Angeles to NYC on Earth.  

In recent years, an unofficial JPL slogan has emerged. It characterizes the can-do approach, hard work, and imagination that have defined the Mars exploration program so far: dare mighty things. It’s inspirational because, as a space-exploring species, we keep living up to it.

NASA’s road map to Mars falls right in line with this operating philosophy. Read the full report here: NASA Mars Road Map

Exploring Chemistry with Fire & Ice

Can you change the speed of a reaction just by changing the temperature? That’s what we’re going to find out! First, we need to understand the reaction:


This balloon is filled with hydrogen, and then it is lit on fire. This is known as a combustion reaction, where hydrogen combines with oxygen. This means that the result of this fireball is actually….H2O, or water vapor! In chemistry, we would write this equation like this:

2 H2   +   O2    →   H2O   +   Heat

While heat may not be a molecule, it is a very important part of the reaction. This all has to do with energy. While hydrogen and oxygen are stable molecules, they store more energy than water. Nature tends to push towards having molecules in the lowest available energy scenario. That seems to mean that hydrogen and oxygen should always be combining and wood should always be on fire (since if fire gives off heat, the result of fire has to be lower energy than the wood), but fortunately this isn’t what actually happens! This is because of the graph below:

Energy Reaction

The curvy red line shows what the energy looks like throughout the reaction. The reactants, as noted above, have higher energy, and the products have lower energy, and the difference between them is the heat. There is also the weird little bump, which is known as activation energy. For the reaction to start at all, some energy needs to be added, which is why we have to light a fire. Touching the lighter to the balloon supplies enough heat to start the chain reaction of combustion of all of the hydrogen.

The hydrogen in the balloon is about 70℉. What happens if we change that temperature? What does temperature mean and why should it matter? When we measure how hot something is, what we are really measuring is how fast the atoms and molecules are moving. For the hydrogen to react with oxygen, it has to be close enough to the oxygen and have heat to start the reaction. Adding liquid nitrogen to the situation cools it down by about 400℉, to -321℉. You can see this immediately by the size of the balloon. It appears to crumple under the weight of the liquid nitrogen, but really the gas inside is just slowing down so much that it can’t push out the sides of the balloon. With the molecules slowed down, the reaction should slow down too! Here they are side by side:

Smaller Fast Smaller Slow


If it looks like the one on the right has been slowed down, it has…by the dramatic change in temperature of the reaction! This may seem exotic, but there are practical examples of this. Refrigerators are used to keep the temperature of your food low to slow down spoiling. Lizards and other ectotherms move more slowly in cold weather as they lack a way to keep up their body temperatures.


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