Edwin Hubble

Distance vs. velocity (away from us)

for a bunch of galaxies

NASA StarChildhttp://starchild.gsfc.nasa.gov/docs/StarChild/questions/redshift.html

Distance (megaparsecs)

Velo

city

(ki

lom

eter

s pe

r se

cond

)

Hubble’s Law

NASA StarChildhttp://starchild.gsfc.nasa.gov/docs/StarChild/questions/redshift.html

Distance (megaparsecs)

Velo

city

(ki

lom

eter

s pe

r se

cond

)

Hubble’s Law (modern data)

Freedman et al. (2001), The Astrophysical Journal 553, 47

Type Ia Supernova

e

(Knop et al. 2003)

Redshift (amount universe “stretched” since the object’s light was emitted)

How

fain

t eac

h ob

ject

app

ears

(whe

n vi

ewed

from

Ea

rth)

≈ Velocity

≈ Dis

tanc

e

Type Ia Supernovae (Riess et al. 2004)

Redshift (amount universe “stretched” since the object’s light was emitted)

How

fain

t eac

h ob

ject

app

ears

(whe

n vi

ewed

from

Ea

rth)

The Cosmic Microwave Background

NASA/WMAP Science Team

The Cosmic Microwave Background

NASA/WMAP Science Team

The Cosmic Microwave Background

NASA/WMAP Science Team