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Projects: Space InformationThe Planetary ReportVolume XXVII, Number 6, November/December 2007
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Credit: NASA / JPL / Space Science Institute |
Why one side of Iapetus is dark and the other side is bright has been a mystery since Giovanni Domenico Cassini discovered this Saturnian moon more than 300 years ago. Cassini's namesake spacecraft is now exploring the Saturn system on a primary mission that will include nearly 80 orbits of Saturn. Cassini swings by Titan on more than half these orbits and has frequent reasonably close encounters with most of the other moons. Iapetus orbits Saturn at three times Titan's distance, so Cassini had only one chance -- on September 10, 2007 -- to swing out on a specially planned, highly elliptical distant orbit and view the yin-yang moon up close.
This global portrait of the bright side of Iapetus shows the
complexity of the boundary between the bright and dark material. Close inspection
of the image reveals that there is no "gray" on Iapetus; moving
from the dark to the bright regions, the dark stain on Iapetus' leading
hemisphere breaks up into smaller and smaller patches, concentrated on crater
floors and equator-facing crater walls.
Image: NASA/JPL/Space Science Institute
From The Editor
"To see the Earth as it truly is, small and blue and beautiful in that eternal silence where it floats, is to see ourselves as riders on the Earth together. . . ."
Those words by Archibald MacLeish, written for The New York Times about the Apollo program, have guided the careers of many of us who were children during the Moon landings and then turned our mature energies and talents to understanding that small planet and the worlds that share its neighborhood.
In the years since Apollo, you and I have seen space exploration falter, recover, and grope for a way forward. As riders on the Earth together, we once had the will and the power to take that first step to new worlds, but in many ways we are farther from Mars now than we were in 1972, when the astronauts left their last footprints on the Moon.
In the years between, you and I have watched as scientists and politicians have been forced to realize that the planet that launched Apollo is small, delicate, and vulnerable. The technologies that powered us to the Moon have also given us the power to change our planet. Unfortunately, with power, wisdom does not always follow.
The time has come for you and I, as riders on the Earth together, to find
new ways to explore and act and work together. Planetary Citizenship, a program
we are developing and announce in this issue, bring you and me together to
better this pale blue dot of ours.
—Charlene M. Anderson
Features
Worlds Beyond
by Andre Bormanis
A Night to Remember: The Planetary Society's 2007 Awards Celebration
by Andrea Carroll
2007 -- The Year in Pictures
by Emily Stewart Lakdawalla
Departments
World Watch
Questions and Answers
We Make It Happen!
Members’ Dialogue
Society News
The Planetary Report is available only to Members of The Planetary Society. If you'd like to read these and other exciting features, JOIN THE PLANETARY SOCIETY TODAY!
MEMBERS: Download this and other back issues of The Planetary Report in PDF format from the For Members section of the website.
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