Australian Sky Telescope MayJune 2017

38 AUSTRALIAN SKY & TELESCOPE May | June 2017

NASA / ESA / HHT (STSCI/AURA)

Sun and the zodiac. In 2017 it glows

northwest of the Sagittarius ‘Teapot,’

not far from the Lagoon Nebula, at

about declination –20°. This makes it

perfect for southern stargazers.

Like any astronomical object, its

best to catch Saturn when it is highest

in the sky, on or near the meridian. In

April that means before the first light of

dawn, and in May between about 2 a.m.

and 3 a.m. Australian Eastern Standard

Time. Opposition comes on June 15.

Not until July will Saturn shine its

highest in the evening.

Saturn’s globe remains about 18′′

wide all the while, and its rings span

about 40′′, roughly a Jupiter-width. This

Saturn’s southern apparition

year the rings are tipped their widest

open — between 26.4° and 27.0° to our

line of sight, a circumstance we see only

twice in Saturn’s 29.5-year orbit.

Here’s a guide to help you make the

most of Saturn from now through the

coming months.

Markings on the globe

Saturn is a gas planet with dusky cloud

belts and brighter zones between them,

like Jupiter. But Saturn is about twice

as far and 16% smaller than Jupiter,

and we see its markings through a

high-altitude yellowish haze. Even so,

with my 15-cm reflector I can almost

always see some of Saturn’s atmospheric

SEEING SATURN by Alan MacRobert

DISK AND RING STRUCTURES are

abundant on every scale throughout the

universe, from rings around planets to

protoplanetary disks to debris disks to

black-hole accretion disks to gas-rich

galaxies. As different as these objects

are, they all take their shape for the

same reason — conservation of angular

momentum in a rotating system of

stuff that can’t get rid of it.

Ringed planets must be abundant

everywhere; all four gas giants in our

Solar System have at least slight rings.

But the wide, dense rings of Saturn are

unique among anything we can see.

Saturn has crept far south in recent

years, in its 29.5-year circuit around the

T While you won't get as good a view as Hubble (it took

this image in 2009), nonetheless Saturn is always

prime viewing with any size of telescope.

With its rings still tipped invitingly open, Saturn invites your most careful scrutiny.