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# Star Constellations

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Infinity and Beyond

### Infinity and Beyond

Credit: ESA/Hubble
Source: http://en.wikipedia.org/wiki/File:Starsinthesky.jpg
License: CC BY-NC 3.0

How many stars are there? How would you even try to answer that question?

#### Amazing But True!

License: CC BY-NC 3.0

Night sky by the John Day River, Oregon [Figure2]

• How could you figure out how many stars there are?
• Count all the stars in the night sky: that’s a pretty low number.
• Estimate the number of stars in the Milky Way Galaxy and multiply by the number of galaxies
• How could you figure out the number of galaxies?
• One idea for the number of stars is: $1 \ \text{septillion}=1 \times 10^{24}= 1,000,000,000,000,000,000,000,000$
• It is also thought that there are an infinite number of stars.

#### Show What You Know

1. Why would you see the most stars when the air is dry and you’re at the top of a mountain?
2. What do you see in a clear night sky besides stars?
3. Why can’t astronomers with good telescopes just count the number of stars in the night sky?
4. Besides looking and counting, how can astronomers try to determine how many stars are in the Milky Way Galaxy?
5. One idea is that there is an infinite number of stars. What does that mean?

1. [1]^ Credit: ESA/Hubble; Source: http://en.wikipedia.org/wiki/File:Starsinthesky.jpg; License: CC BY-NC 3.0
2. [2]^ Credit: Gabriel Amadeus; Source: http://www.flickr.com/photos/gabrielamadeus/8606382411/; License: CC BY-NC 3.0

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