Page 98 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

OBSERVING

SATURN’S MOONS

NEXT TIME YOU OBSERVE THE RINGED PLANET, MAKE SURE
YOU TAKE IN ITS MANY MOONS

Looking at Saturn through a telescope its moons’ visibility during this period, When you’re gazing at it through your
is a glorious sight. However, Saturn is along with the fact that the angle at which scope, you’re not actually looking at Titan’s
best viewed when the ringed planet is at its rings can be seen varies, gives you the surface but at its nitrogen-rich cloud tops.
opposition – when its orbit brings it to its perfect excuse to get out and view this In terms of brightness, Titan can reach
closest point to Earth. The next time you can amazing world. mag. +8.4, putting it well within the reach
get a ‘close-up’ view of Saturn like this will Saturn has 62 known moons, but only of binoculars, while with a small telescope
be when it’s next at opposition on 28 April seven are visible. Due to its sheer size, the you’ll have no trouble seeing it at all.
2013, then again on 11 May 2014. easiest of Saturn’s satellites to see is Titan. Don’t forget that just because you see a
On these dates Saturn will be at its This moon has a diameter of 5,150km (3,200 small point of light near Saturn, it doesn’t
biggest and brightest in the sky – although miles), which makes it bigger than the mean you’re looking at one of its moons.
the ‘biggest’ part is only apparent through planet Mercury. In the moon rankings, it’s As planets travel through space they often
a telescope. This applies to Saturn’s moons the second largest in the Solar System, only drift in front of faint background stars, so
too, which will also be at their optimum beaten by Jupiter’s Ganymede. It’s also the it’s important to know what is a moon and
brightness for observing. The planet and only moon with a substantial atmosphere. what isn’t. You can separate your moons

Saturn’s moons are tricky
but rewarding to observe;
a 6-inch scope is needed to
get the view here, with good
seeing conditions

Mimas

Dione Titan

Enceladus

Tethys

PETE LAWRENCE, NASA/JPL X 5 Rhea

98 skyatnightmagazine.com 2012