Interview with Dr. Ulyana Horodyskyj – Glaciologist

Dr. Horodyskyj is the CEO of Science in the Wild (Boulder, Colorado). This is a citizen science adventure company. Prior to this, she held a post-doc position at the National Snow and Ice Data Center based in Boulder, Colorado. Currently, she is taking people on expeditions around the world and educating them in field science methods, as well as teaching at Colorado College as visiting faculty. Continue reading

Teacher Demo – Water Quality Demonstration

This demonstration shows some differences between potable (drinkable) water and non-potable (non-drinkable) water.  Variations in temperature, turbidity and pH level also determine the types of microorganisms that can thrive in each water sample.  Continue reading

Teacher Demo/Student Activity: Powder Disaster

Introduction

Flour is an ingredient that is found in most kitchens and used regularly for baking and cooking.  Consequently, it is considered safe, and people do not regard the potential hazards.  In reality, flour and dust explosions are extremely dangerous, and reducing the risk of such an explosion is a major concern to the agriculture and food processing industries.

The purpose of this demonstration/activity is to illustrate the importance of being aware of potentially harmful situations and practices in the workplace. In particular, the dustiness of a material can affect the nature of chemical reaction, affecting a safe working environment.

How does it work?

Flour is combustible. When sitting as a stable pile the fuel (flour) is more connected to other flour particles than oxygen particles. As dust, each dust particle is surrounded by oxygen particles. This supports the combustion of the flour particle. As each particle moves through the flame, the combustion moves with the particles. Flour explosions tend to be connected to the movement of flour through air. The source of ignition is often discovered to be a static discharge.

 

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What is the Crater-Dome Illusion?

In interpreting space or aerial photos, it’s important to notice where the source of light is originating. Noticing the light source is what helps you determine whether an object is a depression like a bowl, or a projection above ground such as a mound or dome.

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Teacher Demo: Bright Star or Close Star?

When you gaze up in the night sky, some stars will be very bright while other stars are barely visible to the unaided eye. With the aid of binoculars, you may be able to observe different colours in the stars. The brightness and colour of a star depends on three factors: temperature, distance, and size.

There are two measures of how bright a star appears:

  • The “apparent magnitude” of a star describes how bright the star appears from Earth. This scale ranges from the brightest star in the sky, the Sun, which is set at –26.8. The dimmest stars, which are only visible with the largest telescopes, have an apparent magnitude of 25. The faintest stars visible by the naked eye have an apparent magnitude of 5.5. A decrease of 1 on the scale represents a 2.5 times increase in the apparent brightness.
  • The absolute magnitude of a star is the measure of brightness of a star if it were at a distance of 32.6 light years (ly) from an observer. By placing all stars at this distance, the true brightness of the stars can be compared.

We know that the apparent magnitude of the Sun is the brightest at –26.8. However, when using the absolute magnitude scale, the Sun would be barely visible to the naked eye, with a reading of 4.8.

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