August 2021 BBC Sky at Night Magazine 67

W

hen Earth is directly between

the Sun and another planet,

that planet is at opposition.

This is a great time to view

as the planet appears at its

largest and brightest.

With both Jupiter and Saturn at opposition this month,

Pete Lawrence looks at how to best gather valuable

details about them with your observations

Giants at

OPPOSITION

Gas giants Jupiter and Saturn are both coming

to opposition in August and are impressive to view

through a telescope for different reasons. Jupiter’s

dynamic atmosphere shows lots of detail and

changes markedly over time. Saturn’s atmosphere

is subtler, but still has the potential to surprise.

And, of course, although Saturn’s globe doesn’t

show the drama present on Jupiter, its rings are a

constant draw. Over previous years, both planets

have appeared low from the UK, which has made

observing them harder. The conditions are now

slowly changing and it’s a great time to discover how

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Observing the gas giants

Despite their great distances, Jupiter and Saturn are

physically large enough to appear bright and with

tangible size through a telescope. Jupiter shows a

wealth of detail, which is fascinating to record, either

by sketching or imaging. As it rotates in less than

10 hours, you don’t have to wait long for its appearance

to change. Indeed, wait too long and the planet’s fast

rotation hides features and reveals new detail.

Saturn rotates quickly too, but it’s a different world

in terms of visual appearance. Indeed, Saturn’s banded >

< ...whether it’s to evaluate the visual brightness of

Saturn’s different regions (see box, page 71), or to

capture a shadow transit in progress on Jupiter's disc