Page 10 - (DK) Eyewitness - Mars

Astronomers focus on Mars

The term astronomy combines the Greek astron, “star,” and
nomos, “law.” Generally, astronomy is the study of planets and stars
and the laws that govern their movements and dimensions. Early
astronomers calculated the orbits of heavenly bodies by using
mathematics, especially geometry. Poland’s Nicolaus Copernicus
(1473–1543) led the way to understanding the “heliocentric”—
“sun-centered”—theory of the Solar System. This broke with the
geocentric system of Ptolemy, which placed the Earth at the NICOLAUS COPERNICUS
center. Later astronomers confirmed Copernicus’s theory by using This 16th-century Polish astronomer’s
theory that the planets revolve around
the “perspicillum,” or “optick tube.” This magnifying device, the Sun won a growing following among
scientists. Leading astronomers such as
renamed the telescope, came into use in the 1600s. By the 1800s, Johannes Kepler accepted heliocentrism,
scientists studied Mars with increasingly powerful telescopes, and but many philosophers and religious
leaders did not. They believed in
believed they saw canals and seas. Some geocentrism well into the 1700s.
thought Mars might have age-
old civilizations that were HUYGENS AND THE HOURGLASS SEA
further advanced than Dutch astronomer Christiaan Huygens
(1629–1695) was one of those astronomers
those of Earth. using ever-improving telescopes to study Mars.
Huygens sketched
pictures of a dark
KEPLER’S ORBITAL MATH smudge he noted on
Johannes Kepler (1571–1630) the planet. This was
studied mathematics in his named the Hourglass
native Germany. He was Sea because of its shape.
also interested in astronomy. Seen more clearly in
By closely observing Mars, improved telescopes
Kepler discovered that the two centuries later, it
planets follow elliptical would be renamed
orbits, not perfect circles. Syrtis Major.
Using his knowledge of
mathematics, he calculated
the planets’ orbits. Kepler also
invented an improved telescope. Framework for
aiming telescope

Pondering life

on Mars

As a young man William Herschel Telescope tube
(1738–1822) moved to England
from his native Germany and
taught music. Herschel was also a
dedicated astronomer who built
his own telescopes. He was
especially captivated by Mars,
which he thought was much like
Earth. Huygens and Herschel were
among the first to say Mars might
have living beings. William Herschel

HERSCHEL’S TELESCOPE
A student of optics, Herschel built telescopes that used
large mirrors to collect starlight. His “reflecting”
telescopes were the best of their era, and with them he
discovered Uranus in 1781. Herschel also studied Mars
and was convinced that the polar regions of Mars
contained areas of ice, which decreased when they
partially melted in summer and grew larger in winter.