Yearly Archives: 2018

Asteroid to Meteorite to Crater

Every day, about 40 tons of space rocks reach the top of Earth’s atmosphere. These asteroids come in many different sizes and have been floating around in space for billions of years. Once they reach the Earth, however, they become meteors — more colloquially known as shooting stars.

Meteorite 1

Friction with the air causes the rock to ignite and luminesce. Most of these are pretty dim and can only be seen at night. And most of these are also too small for any chunk to reach the surface of the Earth; the heat and friction vaporize the meteors completely. However, sometimes the meteor is large enough to withstand the friction until it hits the surface. These are classified as meteorites. Very few of these are large enough to leave a significant impact, but every once in a while, a large meteorite touches down. When this happens, it compresses the surface, which will decompress moments later as a shockwave, traveling through the rock and carving out a crater.

Meteorite 2

Very rarely, an extinction-level event meteor collides with our planet. Such an event happened 66 million years ago, and is a possible cause of the major extinction event that killed all the dinosaurs. The impact is hypothesized to be a billion time stronger than the first atomic bombs, sending ash and dust into the air that blocked sunlight for more than a full year.

Meteorite

Thankfully, such events are incredibly rare, so the most you’ll have to be worried about is a small dent in your car — and even that is unlikely to happen!

Written By: Scott Yarbrough

What is a Tippe Top and How Does it Work?

At first glance, a Tippe Top looks like a normal spinning top. A few moments after you spin it however, the tippe top flips over and begins spinning on its thin stem, raising its center of mass upwards! This marvel of a toy stumped physicists and was popular among many well-known figures in the mid-1900s.

tippe top

The strange mechanics that add potential energy to the toy fascinated Nobel Prize winners Niels Bohr and Wolfgang Pauli. It was originally designed in the mid-1800s, but was reinvented in the 1950s and sold as a toy. Very popular at the time, it drew the attention of physicists who sought to figure out exactly what was happening.

tippe top physics

In order to flip over and raise its center of mass, the tippe top needs to translate some of its rotational momentum. It does so because its center of mass is actually lower than its geometrical center. As it spins, the rotational axis is offset from the point of contact with the table, which causes the top to trace out a circle on the table.

tippe top  gif

The friction with the table applies a torque that causes the top to tip over, changing its angular momentum. When it becomes horizontal, the top actually reverses its direction of spin! Once the stem hits the table, the torque causes the top to flip over! It’s spinning slower than it was before, and that energy has gone into gravitational potential energy!

It just goes to show that even simple-looking toys can have some cool and challenging physics behind them! You just have to stop and think about how they actually work.

Written By: Scott Yarbrough

How to Tie Some Knots

One of AstroCamp’s best activities is our ropes course! From zipline to skycoaster, we encourage kids to push themselves to overcome the challenge. But there’s a lot of unseen work that goes into setting up these activities! One of the most important jobs is getting all the knots tied!

We use an assortment of different knots on our ropes courses. If you want a step-by-step instruction of how to tie a few of them, check out the video above!

knots 8

The “Figure-8” and “Figure-8 on a Bight” knots feature heavily on the ropes course. They’re easy and strong knots, and feature heavily in rock climbing. The allow us to connect carabiners to the participants. The Figure-8 on a Bight is usually accompanied by some sort of stopper knot to prevent the line from slipping. If you’ve ever been attached to a rope at AstroCamp, it’s most likely been via this knot!

8 knots

The third knot we show in the video is the “Alpine Butterfly.” It’s a unique knot in that it can be tied at any point on the rope without needing to access either end. It creates a fixed loop, where a carabiner or another rope can be attached. We use this knot on the skycoaster to retrieve the line after you’ve pulled the release cord. It’s also how we attach you to the haul rope that you use to get the skycoaster participant up into the air in the first place!

butterfly knots

There are quite a few other knots that we use on the ropes course, but these are three of the most common. With just a small length of rope, you can practice them and become a ropes master!

Written By: Scott Yarbrough

Does Salt Water Boil Faster?

It seems like there’s an old wives’ tale for everything — from cleaning to maintaining your health, there’s always some trick to doing things better. The same goes for cooking, too! One of the classic examples is to add salt to your water in order to get it to boil faster. But is this actually true?

salt water cooking

Adding salt to water is going to do two things to water’s physical properties: it will raise the boiling point and it will lower the specific heat. These two changes actually work against each other. Raising the boiling point will make the water boil slower. We’ll need to get it to a higher temperature, which may mean a longer time on the stove. But lowering the water’s specific heat — AKA, the amount of energy needed to change an object’s temperature — will cause the salt water to heat up faster! So which effect is stronger?

salt water vs boiling

The answer isn’t an easy one. It will depend on how much salt you put into your water. In our experiment in the video above, a decent amount of salt raises the boiling point a significant amount, but does not speed up the process by much, if at all. But if we wanted to, we could speed it up more by adding more salt.However, if we look at this from a practical standpoint, you don’t actually want that much salt while you’re cooking. A little bit will go a long way to making your food taste good, but too much will ruin your dish.

salt water boiling pt

So it’s possible that the wives’ tale is correct about your food cooking faster, but perhaps for just the wrong reasons. If you’re making pasta, or a stew, or something that requires a pot of boiling water, a higher boiling point will actually mean your water is hotter and will cook the food quicker. It may take longer to get to the boiling point, but once you’re there, the cooking time is cut down considerably.

Written By: Scott Yarbrough

 

Why Do We Have Seasons?

Happy Thanksgiving! It’s been almost two months since autumn started — the leaves have begun to fall, and the air is getting a lot cooler. Without fail, this season comes at the same time every year and there’s a simple reason for it!

thanksgiving

It’s a common mistake to think that the seasons change due to the varying distance between the Earth and the sun. This is a thing that happens, but the real reason for the cycle is the Earth’s axial tilt. The axis upon which the Earth spins (once every 24-ish hours, resulting in our day-night cycle) does not line up perpendicularly with our orbital path (the oval-ish path the Earth takes around the sun).

thanksgiving

Instead, the Earth makes a 23.5° angle with the perpendicular, changing by only a few degrees on a 40,000 year cycle. Scientists believe this tilt occurred in the early days of our solar system, when our planet was not quite done forming. A large piece of space debris — called a “planetesimal” — collided with the early Earth, pushing it slightly on its side.

 

So what does this have to do with the seasons? Well, as the Earth orbits the sun, its axial tilt doesn’t change. So the northern and southern hemispheres receive different amounts of sunlight at different times of year. When the northern hemisphere is tilted towards the sun, it receives more direct sunlight for longer, causing that half of the planet to heat up more. Six months later, when the same hemisphere is tilted away from the sun, it receives less direct sunlight for less time, allowing that half of the planet to cool off.

thanksgiving seasons

As mentioned before, the Earth-Sun distance does change throughout the year — by about 4 million miles. The period when it’s at the shortest distance is during the southern hemisphere’s summer. All things equal, we would expect that summers in that hemisphere would be hotter and that winters would be colder, but that’s actually not the case. Since the southern hemisphere has a higher percentage of ocean, and since water requires a lot of energy to heat up and cools down very slowly, southern hemisphere seasons are actually milder than the seasons in the north.

So, as the cycle of seasons continues, we can eat our turkey and mashed potatoes and apple pie, and be thankful that this will all happen again in just another year’s time.

Written By: Scott Yarbrough

Newton’s Law of Cooling

One of Newton’s famous contributions to physics was his work in thermodynamics — the study of heat and energy flow. He developed a physical law that showed the proportional relationship between heat loss and the temperature difference between an object and its surroundings: Newton’s Law of Cooling. Despite its name, it can be used to show how an object will cool or heat in its surrounding.

Newton's Law of Cooling 2

It’s worth mentioning that heat and temperature are two separate — but related — values. Heat is a measurement of the total kinetic and potential energy stored in the molecules of an object, while temperature is a measurement of the average kinetic energy. Heat depends on the speed, the number, and the type of molecules. So while a cup of coffee may have a higher temperature than something like an iceberg, the iceberg is made up of so many molecules that it has more heat, and thus more energy.

Newton's Law of Cooling 3

Nevertheless, heat and temperature are related. As an object gains heat, its temperature will also increase. When talking about Newton’s Law of Cooling, it can actually be rearranged to create an equation to show the temperature as a function of time.

Law of cooling

Where Ts is the surrounding temperature, T0 is the initial temperature of the object, and k is a constant.

This equation looks pretty confusing, but all it essentially means is the temperature of an object will decay (or increase) to match the temperature of its surroundings. The change will happen quickly at first, but it will slow down as time goes on.

Newton's Law of Cooling

This theory allows scientists and engineers to correctly predict how certain materials will behave in different conditions. These types of calculations are done for anything from insulated coffee mugs to space rockets. They can then safely manufacture these to prevent any damage or harm.

Written By: Scott Yarbrough

What is a CCD Telescope?

During our Space Night, you’ll eventually find yourself in an area with tools that allow you to look at the beautiful night sky. Each station has its own set of binoculars, Dobsonian telescope, and either a Celestron or Meade telescope mounted on an electric motor. But in the center of the telescope area sits another type of telescope. This telescope has the ability to take images of objects that are too dim for our eyes to see. This is our CCD telescope!

ccd telescope

At first glance, there’s not much different about it. It’s a little bigger, its mount is different than the others, but instead of an eyepiece attached to the end of it, there is a special camera mounted to the front. This camera has computer cables that allow it to be controlled by a special laptop, and it can take photos of very dim space objects.

CCD telescope chipThe CCD chip is a very sensitive device. It can count individual photons (particles of light) as they hit the sensor and then convert them into electrons. The more a particular area is struck by photons, the more electrons it will generate. This electrical signal is what gives us our image.

While looking through a telescope with an eyepiece, our eyeballs are doing the equivalent of taking many images every second. The telescope helps us see dimmer objects than we’d normally perceive, but there’s nothing we can do about taking longer exposures with our eyes. The CCD camera changes that. It can keep its sensors on for a long amount of time, gathering and collecting light for thousands of times greater than our eyes can.

CCD telescope kepler

The CCD onboard the Kepler Space Telescope. Credit: NASA

These telescopes are used all around the world by amateur and professional astronomers. They can also be found beyond our planet in space telescopes like Hubble or Kepler! These devices allow us to view faraway objects and help us unravel the mysteries of our universe.

Written By: Scott Yarbrough

Oxidizing Metals vs Organic Materials

When certain metals reach a high enough temperature, they can catch fire. What’s happening here is similar to what happens when wood ignites. The material captures oxygen from the surrounding air and binds it in a reaction that gives off heat and light. This reaction is the fire that we see.

oxidized metalWe define “organic material” as any carbon-based object. It doesn’t necessarily need to be alive to be organic, but many organic compounds are alive, or were at some point. When an organic compound like wood burns, the oxygen in the air is bound to the carbon atoms found within the material. This releases carbon dioxide and carbon monoxide. Additionally, elements like hydrogen will also react with the oxygen, forming water vapor. These gases are what cause the smoke to rise from the wood. Small bits of unburnable material are left as ashes.

In pure metals, however, there are no carbon atoms. As the metal heats up and oxidizes, the oxygen is mostly being bound directly to the metal itself. In fact, this means that the oxidized metal will weigh more than the starting metal. Since very little material is being emitted as smoke or ash, the majority of the metal is being converted to its oxidized form, seen in the equation below.

2 Fe(s) + O2(g) —> 2 FeO(s)

oxidized metal wool

These reactions don’t have to happen quickly, though. Oxidation happens at slow speeds in metals and organic materials. If you’ve ever seen rust forming on the surface of iron, that’s oxidation  — producing the same material as when it’s burned. Composting — the act of letting organic material decompose to create fertilizer — is also a form of slow oxidation. As bacteria breaks down the organic material, heat and energy are released as the material absorbs oxygen.

oxidized metal compost

These examples of slower oxidation are found all around us. Even though they may not be as dramatic as a fire, they still play an important role in our universe.

Written By: Scott Yarbrough

How We Landed on the Moon

Since 1966, NASA has been landing the unmanned Surveyor probes onto the surface of the moon to collect data. In December 1968, NASA managed to get a manned spacecraft into lunar orbit with the Apollo 8 mission. The next goal to accomplish was to combine these feats in order to land a crewed spaceship onto the moon’s surface.

Moon land

The Lunar Module seen from the Command Module. Credit: NASA

The first step was to find a suitable landing site. The Lunar Module would need to have a flat surface with no craters nearby. Additionally, the area would need to be well-lit enough at the time of landing. The approach would have to be clear so that the landing radar could work at its best. Finally, it would need to be at a location where landing and liftoff would use as little fuel as possible to make the return journey to orbit possible. Using images taken from the Lunar Orbiter satellites, the Apollo 8, and the Apollo 10 missions NASA narrowed down the number of possible landing sites to 5. After further investigation, the final landing site was chosen: The Sea of Tranquility.

moon landed sea

Once Apollo 11 was in orbit around the moon, the Lunar Module detached from the Command Module and fired its engine to begin deorbiting. As it slowed its horizontal and vertical velocity, the Lunar Module used small thrusters to adjust its trajectory until it was hovering above the landing site. Then it slowly descended until it finally landed softly onto the lunar soil.

moon landed 2

After the Apollo 11 mission, five other lunar landings occurred each more successful than the last. These missions helped build the foundation for NASA’s accomplishments over the past 50 years. Without the scientific and engineering breakthroughs of the Apollo program, our understanding of the universe would be vastly less.

Written By: Scott Yarbrough

How We Got to the Moon

During the 1960s, NASA had the daunting task of landing a person on the moon. When John F. Kennedy announced the goal to put a man on the moon by the end of the decade, they had only recently sent Alan Shepard into space for the first time. It would be another nine months before John Glenn would become the first American to orbit the Earth. NASA would need to perfect every step in just 8 short years. The first step is to reach the altitude of the moon. In order to get there efficiently, we must perform a maneuver known as a “Hohmann Transfer.” Designed to minimize fuel consumption, it allows us to build lighter, cheaper spacecrafts.

moon

But once the spacecraft is headed to the moon, it will be going too fast to be fully captured by the moon’s gravity. At this speed, it will slingshot around it and head back to Earth. To insert itself into lunar orbit, the spaceship needs to slow down. The only way it can do this is by burning its rocket in the direction it’s flying. Once it’s burned for long enough, the speed of the rocket is low enough to establish a lunar orbit.

moon 2

moon Both the US and the USSR had been trying to refine this technique since the late 1950s, with little success. Both nations had succeeded in getting impactors and landers onto the moon, but it wasn’t until November 1966 when NASA successfully put an unmanned craft into orbit. In December 1968, Apollo 8 would become the first manned spaceship to orbit the Earth.

Getting to lunar orbit was tricky, but once NASA engineers could consistently make the calculations correctly, they advanced to the next challenge – getting a manned lander onto the surface of the moon.

The USSR’s Luna 2, the first manmade
to reach the surface of the moon.
Image Credit: NASA

Written by Scott Yarbrough

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

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