This new book puts the
fun into gardening for all
the family. Bright illus-
trations and text take
readers in steps to suc-
cessful gardening. And
simple ideas backed by
expert advice inspire
anyone to garden. The
science behind successful growing
is illustrated through experiments,
showing what plants need to grow
and their place beyond your own
backyard. Available at:
australiangeographic.com.au/shopGET GROWING
Australian Geographic, $29.95A great walk can be an exhila-
rating experience that remains
with you forever. Perhaps you’re
stirred by endless mountain views
or soothed by stepping into a
living green cathedral. Maybe
the physical challenge drives you
harder and farther than
you thought possible.
Australia has many
extraordinary walks; this
is AG’s collection of the
best to be found in every
corner of the country.
Available at: australian-
geographic.com.au/shopAUSTRALIA’S
BEST 100 WALKS
Australian Geographic, $29.95READ
READ
Download the Geocach-
ing app to join the world’s
largest treasure-hunting
community. Use the app
on a GPS-capable device
to locate hidden con-
tainers called geocaches.
Once you find one, sign
the guestbook, place the
container back how you
found it and share your
experience with the online
geocaching community. Some
boxes include trinkets such as
small toys that can be swapped
for something of similar value.
Millions of geocaches are hidden
across Earth, in most countries.GEOCACHING
DOWNLOAD
ILLUSTRATION BY: RON MILLERGEOBUZZ
MAKING SATURN
LOOK ORDINARY
★SPACE
T
HE REMARKABLE object I
bring you today was discov-
ered some years ago, but has
recently been in the headlines again.
J1407b is an exoplanet – a planet
orbiting a star outside our solar
system. In this case it’s orbiting a
Sun-like star 430 light-years away
that is part of a bigger group of
adolescent stars.
J1407b was detected by the
dimming of the light of its parent star
as it passes in front of it. This is a
well-established discovery technique
known as the transit method.
Like most exoplanets, it’s too far away
to be seen directly, but the transit
method is a powerful way of investi-
gating such distant objects. And, in
J1407b’s case, it’s revealed much more.
Back in 2007, astronomers
recorded a long and deep dimming
of the parent star displaying complex
structure – short-term changes in the
star’s brightness caused by differing
amounts of obscuration passing in
front of it. These were interpreted as
being due to a system of rings around
the planet, but the big surprise was
the size of J1407b’s ring system.
Analysis shows that it must have
a diameter of about 120 million
kilometres, which is 80 per cent ofthe distance from the Earth to the
Sun. If these rings were around
Saturn in our own Solar System,
they would be easily visible to the
unaided eye.
The rings of Saturn are thought to
have been formed when two icy
moons collided, producing myriad
ice particles that today make up the
rings. But J1407b’s rings are probably
debris left over from the formation
of the planet itself, which may also
have accumulated to form one or
more moons.
And that’s what has brought
J1407b back into the news, with
researchers investigating whether a
large gap in the rings could be
explained by the presence of a moon
orbiting outside them. Sadly, the new
work shows that is not possible.
Something else must be at play –
perhaps an infant moon embedded
in the rings. We’ll have to wait until
the next time J1407b passes in front
of its parent star, which is expected
in the next few years, to discover more.FRED WATSON
is Australia’s
Astronomer-at-Large.This artist’s impression shows the
extrasolar ring system circling J1407b.
The rings eclipse the young Sun-like star
J1407, as they would have when the
exoplanet was first detected in early 2007.26 Australian Geographic