Our Galaxy and Beyond

Our Place in Our Galaxy

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What’s the Difference?

Universe

Galaxy

Image credits: NASA, STScI

Solar System

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What’s the Difference?

Universe

Galaxy

Solar System

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Where is our Solar System?

Visible stars, gas, dust in the Milky Way Galaxy

Image credits: NASA, STScI

Solar System

here

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How big is the Milky Way Galaxy?

100,000 light years

Image credits: NASA, STScI

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How far is 100,000 light years?

1 inch represents 5.5 light hours (Sun to Pluto)

1 mile represents 40 light years

2,500 miles

represents

100,000 light years

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2,500 miles

Continent of North America!

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And how thick is our Galaxy?

Credit: NASA, COsmic Background Explorer (COBE) Project

~1000 light years

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How thick is 1,000 light years?

If 2,500 miles represents 100,000 light years

25 miles represents 1,000 light years

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200 BILLION Stars!!!

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Fill with bird seed4 feet deep on a football field

200 BILLION Stars!!!

2,500 miles

Spread them over the continent 25 miles deep!

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What’s in our Universe

• Objects in our Solar System– Sun– Planets

• Objects in our Galaxy (The Milky Way)– Star Systems– Black hole– Nebulae– Stars– Globular clusters of stars

• Objects in our Universe…

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Black Hole Space Warp

• In groups– Have two people hold the hoop horizontally.– Place the weight at the center of the hoop.– Have two people slowly toss in the bouncy

balls one at a time. Toss them so that they are near the edge of the hoop when you release them.

– Observe what happens to the path and the speed of the balls.

– Repeat this 3 times.

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Black Hole Space Warp

• In your booklet answer the following questions based on your observations.

1. What do the moving balls represent?

2. What does the weight represent?

3. What happened to the balls?

4. What does the blue latex material represent?

5. What happens to the material when the bouncy balls roll around?

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Monstrous black holes

• At the heart of every galaxy lies a black hole, millions to billions times the mass of our Sun

HST/NGC 4261800 light years

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The Black Hole at the center of the Milky Way

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Masses of Black Holes

• Primordial – can be any size, including very small (If <1014 g, they would still exist)

• “Stellar mass” black holes – must be at least 3 Mo (~1034 g) – many examples are known

• Intermediate black holes – range from 100 to 1000 Mo - located in normal galaxies – many seen

• Massive black holes – about 106 Mo – such as in the center of the Milky Way – many seen

• Supermassive black holes – about 109-10 Mo - located in Active Galactic Nuclei, often accompanied by jets – many seen