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Friday, January 25, 2013

SciShow Video: Can We Predict Earthquakes?

This 4-minute video explains the challenges of predicting earthquakes in the short-term.

To view a convenient list of all the resources that have been posted on this "Earth Science Guy" blog site, CLICK HERE.

Friday, January 18, 2013

A Model to Help Explain the Aurora Borealis

Right: This model, made with a styrofoam sphere, pipe cleaners, and a little glue shows the relationship between the magnetic field (blue lines) and the auroral oval (yellow ring). It's a great prop to use as you explain the Northern Lights.

Many people think that sunlight reflecting off of ice at the poles causes the northern lights. This is not true! The true cause of the lights is a combination of three factors - the solar wind, Earth’s magnetic field, and the atmosphere.

The solar wind . . .
The sun is constantly emitting charged particles (electrons and positive ions). This invisible "wind" of particles, called plasma, varies in intensity depending on how active the sun has been. If there is some sort of flare or other type of "storm" on the sun, the solar wind becomes stronger.

Earth's magnetic field . . .
We are protected from the harmful effects of the solar wind by Earth's magnetic field. The magnetism of our planet forms an invisible shield represented by the blue lines (pipe cleaners) on the model above.

Earth's atmosphere . . .
As the solar wind encounters our magnetic field, the lines guide some of the charged particles down toward the Earth. As the particle enter our atmosphere, something similar to what happens in a fluorescent light bulb takes place. The charged particles "energize" gases in the atmosphere, causing them to emit light. The normal position of the auroral oval is far to the north of us. The city best positioned to see the light show may be Fairbanks, Alaska. As long as the night is dark and clear, there is a very good chance that residents of central Alaska will see the lights. A similar ring of light exists near the Magnetic South Pole (the southern lights; Aurora Australis).

So what does it take for us to see the lights in the "Lower 48"? . . .
In order for the oval to be present at lower latitudes, there must be some sort of storm on the sun. If such a storm causes a burst of solar wind (coronal mass ejection) this can disrupt Earth's magnetic field, causing those invisible lines of magnetism (blue lines on model) to enter the Earth much farther to the south of their normal position. This happens more often during a "solar maximum": a year when the sun is especially active. The last solar max occurred in 2001 and the next is expected in the Autumn of 2013.

To learn more, here are few more resources:
1. Aurora FAQs
2. Montana Earth Science Picture of the Week
3. The Solar Max is Coming!
4. Aurora Forecast Page

To view a convenient list of all the resources that have been posted on this "Earth Science Guy" blog site, CLICK HERE.

Friday, January 11, 2013

Interactive Plate Tectonics Animations and Maps

I like to show students animations of concepts and processes as I am explaining them. Links to online animations can easily be included in PowerPoint presentations. This week's resource is a site that offers the type of animations that I like to use. The site is a product of Scripp' Institute of Oceanography, and it has some nice interactive animations related to plate tectonics. CLICK HERE to see an animation of sea-floor spreading. An icon in the upper right of the animation screen enables you to cause magnetic reversals as you are explaining it. There are some good questions for discussion below the animation.

The site also features an interesting Summary Map that illustrates several aspects of plate tectonics. Menu choices near the top allow you to chose what appears on the map.

Another interactive map allows you to view the position of the continents at various times during the past 600 mya. CLICK HERE to see it. To view a list of everything else the site has to offer, CLICK HERE.

To view a convenient list of all the resources that have been posted on this "Earth Science Guy" blog site, CLICK HERE.

Friday, January 4, 2013

"The Day the Mesozoic Died" - Free Video is Excellent!

As I was thumbing through a recent NSTA publication, I came across an advertisement for a video titled, "The Day the Mesozoic Died"; a 33-minute program produced by the Howard Hughes Medical Institute (HHMI). I went online to watch the video as I was eating breakfast this morning. Wow, this is a GREAT video! . . . and it's free. Here is the web site where you can watch it and/or order a DVD to show your classes: The Day the Mesozoic Died

The video focuses on geologic clues that led to acceptance of the theory that an asteroid impact killed of the dinosaurs. I ordered the video and plan to use it after my students learn how geologists interpret rock layers (superposition, cross-cutting, inclusions, etc.)

The HHMI site also provides several classroom ready resources to complement the video, including a quiz, as well as teacher guidelines and student handouts for several activities. To access those, CLICK HERE.

Learn more about the impact theory here: K-T Boundary in Montana

To view a convenient list of all the resources that have been posted on this "Earth Science Guy" blog site, CLICK HERE.