Page 28 - Astronomy - October 2017 USA

Close encounters with the

The probes not only returned stunning 2

images of Saturn and its rings — they

also set the stage for the highly successful

Cassini mission. by Liz Kruesi

1

ome call Saturn the jewel of the the beautiful and intriguing ringed world
solar system, with its distinc- and its equally fascinating system of
tive rings, variety of moons, moons. The planet hosts a wide array of
and swift atmospheric winds. astronomical processes and structures, and
SThe first glances of the planet the Voyager probes were the first to show
through a telescope certainly form a mem- scientists how incredible the Saturn system
ory that sticks in peoples’ minds. Whether truly is. The system they uncovered was
you’re a backyard observer or a planetary too intriguing not to revisit, laying the
scientist, Saturn is a fascinating world. foundation for the groundbreaking Cassini
For centuries, astronomers using tele- mission decades later. The pair of probes revealed many unex-
scopes spied a ring of material circling the pected details about the Saturn system, but
planet’s equator. Pinpricks of light, the Toward the ringed world Voyager 1 was not the first mission to snap
planet’s moons, floated nearby. Technical The twin Voyager spacecraft launched 16 an up-close view of the planet. That title
advances led to better views, until scientists days apart in 1977, beginning their Grand belongs to Pioneer 11, which flew by the
could see gaps or divisions in the material Tour of the outer solar system. They took ringed world in 1979. Its photographs,
ringing Saturn. They also saw oddities on separate journeys to the ringed planet and combined with ground-based detections,
its moons: One seemed to hold a methane its diverse moons. Voyager 1 arrived in helped planetary scientists better plan the
atmosphere laced with clouds, while November 1980, and afterward used the Voyagers’ Saturn flyby routes, as well as
another was two-faced, bright on one half planet’s gravity to slingshot itself out of choose which targets to focus on.
but dark as asphalt on the other. the solar system’s plane. Voyager 2 swung Each closest approach was a quick
But it would take Voyager 1 and 2, a through in August 1981, continuing on to encounter — after all, the probes were
pair of visiting spacecraft, to fully reveal Uranus and Neptune. traveling faster than 9 miles per second

28 ASTRONOMY • OCTOBER 2017