The Human Cosmos

in powers of ten

0

10 km

0

< 500 BC Ancient World

10 km ?

1

200 BC Greek Astronomy

4.5 million km

Aristarchus - estimates relative distances and size of earth,

moon and sun from watching the shadow of the earth on the

moon during eclipse.

Eratosthenes - measured the size of the earth from the angle

the sun cast on a well at summer solstice (6100 km vs 6378

km).6

14th CenturyIbn al-Shatir141 million km

QuickTime™ and a decompressor

are needed to see this picture.

8

Stronger

geometric

proofs revise

the estimates of

the distance to

the sun

Tycho Brahae

the 1572 supernova

Copernican system

the orbit of Saturn

1.52 x 109 miles

9

1780 Herschelestimates size of the Milky Way by counting

stars in each direction

9000 light years

16

1838 - Friedrich BesselMeasures distance to nearby stars by

Parallax

More accurate size of Milky

Way

91,500 light years

17

QuickTime™ and a decompressor

are needed to see this picture.

19

1923 Edwin Hubble “Nebulae” are other galaxies

Andromeda Galaxy

2,900,000 light years

Discovery of the expansion of space

23

Hubble constant (H)

Shows Universe is Expanding1/H 13 billion light years

21-23

Most distant Galaxies

1975 Dark Matter13 billion light years

1995 Hubble Telescope

Deep Field Pictures

2002 Acceleration of universal expansion

Dark Energy15,000,000,000 light years

23