Meteor Crater

After we visited the Grand Canyon, we visited Meteor Crater, a ¾ mile wide impact crater in a northern Arizona desert. It is said to be the best-preserved crater in the world.

In this photo, you can see the crater's bumpy rim
on the horizon.

Scientists believe that Meteor Crater was formed 50,000 years ago by a meteorite only 50 meters wide. It blasted such a large crater because it moved at a rate of something between 37 and 60 times the speed of sound. That's very fast. When the meteor hit the ground, it gave off energy equivalent to 10 - 20 million tons of TNT.

The meteorite became extremely hot when it hit. It became so hot that most of it was vaporized, and the rest melted. The ground where it hit was no more fortunate; it vaporized and melted, too. A large quantity of material was thrown away from the site, and rained onto the ground for miles around.

After the impact, fragments of the meteorite that had broken off in mid-air fell out of the sky onto the ground. Due to higher air resistance, they fell at a much lower velocity than the main meteorite, so they survived impact. Some of those fragments are on display in the museum next to the crater.

When we visited Meteor Crater, the wind was very, very strong with nothing out in the flat desert to stop it. At the edge of the crater, the wind was intensified as it blew up and over the rim. The fee was more than we had expected - $16 for adults, $8 for kids. When my mom had visited the crater for the first time many years ago, the fee had only been $1. I didn't want to turn around without viewing the crater, so my mom paid the money and we went in.

The middle observation deck, about ⅔ up the crater wall.

It wasn't as much of a rip-off as we originally thought. Admission to the museum was included, and there was a short movie followed by a presentation. I had planned on going down into the crater, but it was off-limits for reasons of preservation and liability; plus, the sides of the crater were steep, and the wind was blowing very hard. So instead, I satisfied myself with looking through the telescopes on the observation decks.

A mine shaft. You can also see a 6 ft astronaut cutout and flag if you
look closely; those are memorials of NASA's training in the crater.

In the picture to the right, you can see some old equipment and light-colored soil. Here's why it's there: in the early 1900's, Daniel Barringer tried to find the meteorite that had excavated the crater. He thought the meteorite was as large as the crater, and wanted to sell the metal from it. For 27 years he searched by drilling into the ground, but he never found anything worthwhile. The soil, I presume, is from his drilling, and it's probably the same with the equipment.

I find Meteor Crater very impressive; it is the mark left by an event that released an enormous amount of energy all on a small place in an instant, wreaking havoc and destruction. Yet it shows how even the most powerful and significant events can fade and disappear, while everything continues on as if it never happened - the only memory of the disaster being a hole in the ground.

For the next post in the Arizona Road Trip series, go to http://greatmst.blogspot.com/2013/03/the-desert-museum.html

The Grand Canyon

On the second day of our road trip (see my last post here), we visited the Grand Canyon, which is in northern Arizona.

The Grand Canyon was formed by the Colorado River. The river ran over soil on the ground, and washed it away. Soon the river got to solid rock, and began to wear through that, too. As it wore through the rock, a huge gorge formed, with the river flowing through it. That gorge was the early Grand Canyon.

As time went by, the canyon got deeper and deeper. The sides of the canyon fell into the river at places, and the river washed it away. When it rained, creeks and streams ran down into the canyon, eroding the sides and giving it an intricate, complicated shape.

Finally, after about 40 million years of erosion, my family and I came along, and looked at the result. It's pretty impressive. Unfortunately, it was rather cold at the time, so we weren't able to stay as long as we would have liked; but it was a great experience just the same.

While I was there, I took the stereoscopic pair of images you can see at the bottom of the post. If you go cross-eyed until the images completely overlap, the combined result will appear 3D. It is very hard for inexperienced people to do that; if you have trouble, try this: put your fingertip in front of the screen, below the photos. While looking at your fingertip, slowly bring it closer and closer to your face. Keep your head level relative to the photos while you do this. Pay attention to the two photos, and stop moving your finger when the photos completely overlap (about 1 foot from your face). Carefully look at the photos; do not allow your eyes to readjust. If you're lucky, the result will be an image that appears 3D. If not, that's okay; some people just can't do it.

For the next post in the Arizona Road Trip series, go to http://greatmst.blogspot.com/2013/02/meteor-crater.html

Arizona Road Trip

I am currently on vacation in Arizona. It's really interesting here. For one, there are cool plants here that aren't where I live - like palm trees, and cacti taller than houses. For another, the weather is really nice; sunny  most of the time, and not too cold.

To get to the place we're staying, my family drove for two days, from Colorado through New Mexico to Arizona. Here are some of the photos I took along the way (just click to view):

Polarized Light

What exactly is polarized light? You may have heard of it before, or read the name. It sounds cool, so what is it? That is what I will explain in this post.

Light is like a wave, or bumpy curve, in many respects. This wave is a sine wave (see my Sine and Cosine post). The wave can oscillate (wobble) in an up-down motion, or a left-right motion; sometimes it does a mixture of both, and wobbles in a circular pattern.

Look at the wall, or the floor. There are quadrillions of light waves bouncing off them. Some of the light waves oscillate in an up-down motion, others oscillate in a left-right motion, and others oscillate in a diagonal motion. The different types of waves are all jumbled together. Is it possible to have a bunch of light waves that all wobble the same way? Yes! Light like that even has a name: polarized light.

You can buy filters that will polarize light; the filters are called polarizers, or polarized filters. Some sunglasses are made with polarized lenses; those are called polarized sunglasses.

There are many uses for polarizers and polarized light. I will discuss some of these uses in later posts.

Sine and Cosine

Trigonometry is the study of the relationship between the angles and sides of triangles. The two most essential parts of trig are the functions sine and cosine. Both take an angle, and return a number. The way they work is really quite simple.

A diagram showing sine (abbreviated sin) and cosine (cos)

To find the sine of the angle θ, draw a circle with radius 1 on a graph, and put the circle's center at the origin of a graph. Find a point on the edge of the circle. The point makes an angle with the center of the circle; make sure that the angle is θ. Sine of θ is the point's y-coordinate. Cosine is the point's x-coordinate. (See the picture to the right.)

Sine and cosine are very useful for calculating heights and distances. For example, let's say somebody needs to know the height of a sky scraper, but isn't able to measure it physically with a tape. If he walks a certain distance away from it, and looks at the angle it subtends in the sky, he can use trigonometry to figure out its height.

But that's not all. If you graph the sine function, you get a cool wavy line the shape of a ripple in water. That curve is called a "sine wave". The same curve is also the building block for the shapes of sound waves. Who said math had to be boring? Not I.