'Scientists who made a difference' series

This blog accompanying the biographical sketch of Johannes Kepler looks at a selection of his writing as poetry and a selection of his scientific sketches as art. The 'Poetry' use Kepler's exact words (translated into English) in prose form, using the title 'Absolutely Settled' to focus on the cadence and word choice. It was a strong statement in support of the Copernican view of the earth and planets revolving around the sun. This selection is from Kepler's book Harmonice Mundi (Harmony of the Worlds), published in 1619. The 'Art' uses a sketch of the trajectory of Mars with 'retrograde motion' which occurs when the orbit of Mars around the sun appears from earth to reverse itself due to the fact that the earth is also orbiting the sun. It was published in 1609 in Kepler's book Astronomia nova (New Astronomy).

Absolutely Settled

Johannes Kepler

First, therefore,

readers should take it

as absolutely settled today

among all astronomers

that all the planets

go round the sun,

with the exception

of the moon,

which alone

has the earth as its center;

and its orbit or course

is not large enough

to be capable

of being drawn

in its correct proportion to the rest . . .

Second,

it is settled

that all the planets are eccentric,

that is,

they change their distances

from the Sun

in such a way

that on one side

their orbits

are furthest from the Sun,

in the other

they come closest to the sun.

Drawings of the trajectory of Mars

Johannes Kepler