Page 69 - BBC Sky at Night - September 2017 UK

VOYAGER AT 40 SEPTEMBER 69

CONTINUED OVER THE PAGE

19 DECEMBER 1977 8 SEPTEMBER 1978 21 OCTOBER 1978 5 MARCH 1979 9 JULY 1979
Voyager 1 overtakes its Voyager 1 exits the On a slower trajectory, Voyager 1 makes Voyager 2 makes
twin, placing it on course asteroid belt and Voyager 2 finally exits its closest approach its closest approach
to reach Jupiter first continues on to Jupiter the asteroid belt to Jupiter to Jupiter

< The Golden Records are a snapshot of Earth as it was
Like the Golden Records,
this small flag also made in 1977; etchings on the covers explain how to play them
it to space – it’s sewn into
some thermal lining it overtake its twin and reach Jupiter first. Between
January and August 1979, the Voyagers studied the
Jovian system. They revealed Jupiter’s famous Great
Red Spot to be a complex anticyclonic storm,
found smaller storms throughout the
planet’s clouds and saw flashes of
lightning in the atmosphere on the
night side. Jupiter’s faint, dusty
rings were also discovered, along
with the satellites Adrastea,
Metis and Thebe. But the
highlight of the Jupiter mission
was the discovery of active
volcanism on the moon Io.
Together, the Voyagers observed
the eruption of no fewer than nine
volcanoes on Io. “At that time, the >
system, which was also used to reprogramme the
spacecraft remotely on more than one occasion.
Voyager 2 thunders into
Travelling too far from the Sun for solar panels to
the sky on 20 August 1977.
be employed, the probes rely on three radioisotope It launched two weeks
thermoelectric generators for power. These convert ahead of Voyager 1, owing
heat produced from the radioactive decay of to its slower trajectory
plutonium into electricity.

Messages for ET
Each spacecraft also carries a message from humanity
in the form of a 12-inch gold-plated copper record.
The cover for the Golden Records bear diagrams
explaining how to play them, showing the location
of our Sun and the two lowest states of the hydrogen
atom as a fundamental clock reference.
The selection of content for the record, by a
committee chaired by Carl Sagan, was completed
in six weeks, chosen to portray the diversity of life
and culture on Earth. There are spoken greetings
in 55 languages; 116 images; recordings of natural
sounds; music from Bach, a Navajo Indian song,
Azerbaijani folk music and Chuck Berry; and even
a recording of the brainwaves of Ann Druyan, the
creative director of the project.
Voyager 1 was launched two weeks after Voyager 2,
but on a shorter and faster trajectory that would see

skyatnightmagazine.com 2017