Ball fired upward from a moving cart

Here is a link to a youtube video of a ball shot upward from a moving cart.

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The scale of the Universe

I was just writing up a lesson for my Earth Science students.

  • At first I convince them that the Earth is HUGE. We discuss that if the Earth were shrunk to the size of a basketball, it would be incredibly round and smooth. More so than a billiard ball. Mount Everest, the Grand Canyon and the deepest depths of the ocean (which seem immense to us) would not be noticeable.
  • Then we make a scale model of the Solar System, with the Sun the size of a basketball. The Earth is as small as the head of a pin, and located over 100 feet from the sun. The Solar System is about 2 miles across. The nearest star is about in Hawaii! Think about how empty space is. Between here and Hawaii, there are only two stars, which you could hold in your hand, and a few tiny, insignificant planets.
  • Our galaxy, the Milky Way is made up of hundreds of billions of stars! How big it must be!

Below is a representation of the Milky Way. (We can’t get a picture, since we are inside of it!)

Below is a picture of the Andromeda Galaxy. Pretty beautiful!

  • The Universe is made up of hundreds of billions of these HUGE galaxies! Below is a picture of a tiny slice of the sky taken by the Hubble Space Telescope. Imagine all of those galaxies, each containing hundreds of billions of stars. Each star might have planets of its own.

Whenever I teach this lesson, I am awed by how insignificant we are in the Universe!

Star trails

I found a cool video showing time lapse photography of the apparent paths of the stars over the course of a night. (This is something I teach, when I am teaching Earth Science.) See if you can identify the North Star. Here’s the link:

http://www.youtube.com/watch?v=3V3rmDG5J8A&feature=youtube_gdata_player

Note: It is difficult to see the stars on an iPhone, but on an iPad or desktop they are much clearer.)