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3.1 Cosmic Distance Ladder. From these methods: Determine distance (see p 615 including Fig 20.16)

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Presentation on theme: "3.1 Cosmic Distance Ladder. From these methods: Determine distance (see p 615 including Fig 20.16)"— Presentation transcript:

1 3.1 Cosmic Distance Ladder

2 From these methods: Determine distance (see p 615 including Fig 20.16)

3 From these methods: Determine distance (see p 626 including Fig 20.16)

4

5 Given luminosity infer distance (see p 626 including Fig 20.16) Use surface temperature of “main sequence stars” to infer Luminosity.

6 Use pulsation period of variable starts (“Cepheids”) to infer luminosity Given luminosity infer distance (see p 626 including Fig 20.16)

7 Use “Tully-Fisher relation” to infer galaxy luminosity from rotation speed

8 Given luminosity infer distance (see p 626 including Fig 20.16) Use “Tully-Fisher relation” to infer galaxy luminosity from rotation speed

9 From these methods: Determine distance (see p 641)

10 3.2 The Redshift

11 Fig 20.15 A redshifted galaxy spectrum Redshift: For small z

12 3.3 The Hubble law

13 Putting together info about speed v and distance d reveals remarkably simple behavior: Km/Sec/Megaparsec 1 Megaparsec = 3.3 million lightyears

14 Special feature of the Hubble law: It looks the same from any position:

15 The Big Bang

16


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