Above: Jupiter presents a wealth of detail in
amateur telescopes. Image Damian Peach
of the planets
Although this year may not be a standout year for Jupiter, Damian Peach
shows that it still keeps its crown as king of the planets.
uring the cold January mornings nightly motions of the four Galilean moons
many observers out during the early (Io, Europa, Ganymede and Callisto) as four
hours will note the giant planet bright points close to the small Jovian disc.
Jupiter again returns to our skies. Despite Using a good 15cm (6-inch) reﬂector
not being in a great position for Northern or 10cm (4-inch) refractor will reveal all the
Hemisphere observers when it reaches major dark belts and bright zones, as well
opposition on 6 June 2007, Jupiter will still as features such as the Great Red Spot and
present a large disc, so even though it will wispy festoons projecting from the dark
not be high in the sky, plenty can still be seen North Equatorial Belt (NEB). Those with
and imaged through amateur telescopes. larger telescopes in the 20cm plus range
At opposition, Jupiter will be placed in the Jupiter reveals a wealth of ﬁne detail under
southern constellation of Scorpius, only good conditions. Jupiter shows a great range
seven degrees from the deep red star Antares of features and the terminology takes some
and the two will make a prominent pairing to become familiar with. The two major
throughout the year. belts of the planet are the NEB and the
Jupiter’s observable atmosphere is South Equatorial Belt (SEB.) All the major
structured in alternating dark belts and belts and zones are displayed in the diagram.
bright zones. The actual boundaries of Jupiter’s rotation period (unlike that of
the belts and zones aren’t deﬁned by Earth) is divided into three systems due to
their appearance, but by their latitudinal the clouds in the equatorial regions moving
boundaries, delineated by the fast moving faster than the clouds farther north or south.
atmospheric jet streams that keep everything They are called System 1 (the equatorial
‘in check’. regions as far north as, and including,
A question many beginners ask is the NEB’s southern edge and the SEB’s
“what can I see on Jupiter?” The answer is, northern edge), System 2 (the rest of the
generally a great deal with patience. With planet down to the NEB’s southern edge
a good pair of binoculars (10 x 50s are a and SEB’s northern edge) and System 3,
good choice) you will be able to follow the which refers to the rotation period of Jupiter
Above: Jupiter’s largest moons, the Galilean
moons, can be followed as they orbit the
giant planet. The top graphic presents a mock
photographic view of the scene on 24 May, with
Jupiter overexposed from a long exposure to
bring out the moons as they line up to the left Right: Jupiter is ringed with belts,
of Jupiter. The centre graphic shows the view each labelled here in this image, which has
through binoculars on the 3 June, with the south to the top, matching the view seen
moons now all lined up on the opposite side. through some telescopes that invert north and
Finally, the last graphic simulates a telescopic south. Key: SPR: South Polar Region; STB: South
view on 12 June when Io just completes Temperate Belt; SEB: South Equatorial Belt; EZ:
its transit of Jupiter, while Ganymede just Equatorial Zone; NEB: North Equatorial Belt;
reappears from behind the planet’s limb on the NTB: North Temperate Belt; NPR: North Polar
other side. In all instances north is up. Region. Image: Damian Peach.
AN graphics by Greg Smye–Rumsby. Additional graphic design: Greg Smye–Rumsby.
84 Astronomy Now Yearbook 2007
observed at radio wavelengths, and thought of the UK often suffer from poor seeing THE USE OF COLOURED FILTERS.
to be the rotation period of the planet’s core. conditions, which make obtaining that
The major limitation the observer good image difﬁcult. Once the basics of the One great observing aid not just for Jupiter, but all the
will ﬁnd (given his telescope is of good observer’s telescope have been mastered
planets, is the use of coloured ﬁlters (which screw into
quality and he/she has the telescope in good (collimation, focusing, tracking) they will
the bottom of the eyepiece or camera). These can give
collimation) is atmospheric seeing. The be ready to undertake a night of imaging.
much clearer views of surface/atmospheric details
lower an object is in the sky, the more of I can’t stress enough the importance of
and also aid in estimates of the intensities of various
Earth’s atmosphere its light passes through properly collimating the telescope. The
features. For Jupiter the most useful ﬁlters to aid the
before it reaches the observer. Since Jupiter observer should check the collimation
will appear low in the sky in 2007, the use of before observing or imaging and make
visual observer are red and blue. Smaller scopes (less
coloured ﬁlters to observe and image it will the adjustments if needed. Also once the than 20cm aperture) may prefer orange or light blue.
yield much clearer views than without ﬁlters. CCD camera/webcam has been attached, For example I prefer using orange to red even on my
Red ﬁlters will help enhance the don’t rush focusing. Take as much time as 36cm reﬂector. Filters worth considering are Wratten
blue coloured areas of Jupiter. They also is needed to reach perfect focus. With the #25 (red), #21 (orange), #38A (dark blue) and #80A
penetrate the violet absorbing haze that planet low in the sky it is essential to use (light blue).
hangs over Jupiter’s atmosphere, so will an infrared blocking ﬁlter, especially when
penetrate deeper into the atmosphere. Red imaging with colour cameras such as the
or orange ﬁltered views tend to be by far Philips T oUcam.
the most detailed and I highly recommend Tri-colour CCD imaging is the
them, especially with Jupiter being so low in most challenging area but yields the best
the sky. Blue ﬁlters will enhance the redder possible results. One must obtain a red,
coloured areas of the atmosphere and the green and blue ﬁltered image in under
belts will appear very dark through this ﬁlter. approximately two minutes because of
The Great Red Spot also appears much Jupiter’s fast rotation. Jupiter displays different details through different coloured filters
darker in blue coloured ﬁlters. Observers One area worth special mention as shown in these images. A blue filter was used for the image on
using CCD cameras can also employ a wide during the 2007 apparition is the use of the left, a green filter for the centre image and a red filter for the
picture on the right. Image: Damian Peach.
range of ﬁlters (see The use of coloured ﬁlters).
lters infrared pass ﬁlters for imaging. Seeing
A great way to learn more about Jupiter conditions are much less turbulent in the
and become familiar with its features its far-red wavelengths and images taken
to draw the planet. For centuries this was through ﬁlters that pass light from 700
the only way to record Jovian activity and nanometres and up will produce the best
remains to this day an ideal way to ‘learn results possible with the planet so low in
the ropes’ of observing the giant planet. the sky. These ﬁlters are not expensive
More detail and advice on visual observing and it’s well worth investing in one for
is available from organisations such as the the coming Jupiter apparition.
British Astronomical Association (www. Once the observer has obtained
britastro.org.) the raw images, they can proceed to
processing them on the computer.
CCD and webcam imaging Unsharp masking is by far the most
As well as being a fascinating target for the common routine used for sharpening
visual observer, Jupiter is an excellent target images, and works very well. One should
for today’s amateur equipped with a CCD be careful not to over-sharpen their
camera or webcam. images, but process them so as much
CCD imaging of Jupiter in the last few detail as possible is displayed, with as little
years has revolutionised amateur study of visible noise as possible. Programs such
the planet. Experienced amateurs today as Registax are commonly used to process
are regularly producing CCD images with webcam sequences and this is available Above: Jupiter (upper left) will be six degrees north of the Moon, with
20cm (8-inch) to 40cm (16-inch) telescopes for free download at http://registax. bright red star Antares just 0.5 degrees north, on 28 June. Jupiter and
Antares, twin red objects, will be close together for much of the summer.
that exceed the quality and resolution of astronomy.net/ AN graphic by Greg Smye–Rumsby.
photographs produced from professional
mountaintop observatories 20 years ago. Further advice and information
The very best images produced can resolve Observers should consider sending there
low contrast features down to around 0.2 visual drawings and CCD images to the
arcseconds, giving such images an almost British Astronomical Association. Observers JUPITER FACT FILE
‘Hubble-esque’ appearance. can ﬁnd information on the Jupiter section’s
CCDs today have never been more activities on their web page. Books such as Equatorial diameter: 143,082km
affordable. Equipped with a good 15cm The Giant Planet Jupiter by John Rogers Polar diameter: 133,792km
telescope, webcam and PC, observers can provide a wealth of information about
produce detailed nightly images of Jupiter Jupiter, while The Lunar and Planetary Rotation period of System I: 9h 50m 30s
that are not only fascinating to look at but Webcam User Guide by Martin Mobberley Rotation period of System II: 9h 55m 40s
scientiﬁcally valuable as well. Webcams such would be an excellent choice to learn more Rotation period of System III: 9h 55m 30s
as the Phillips T oUcam, which costs around about the vast subject of CCD imaging of
£50, has brought high-resolution imaging the planets. Mass: 1.9 x 1027kg
into an affordable price bracket and the For me, Jupiter is without doubt the (as much as all the other planets put together!)
keen amateur could equip themselves with planetary jewel of the sky. Large, bright and Mean albedo: 0.52
a system that could produce detailed images always changing in an appearance it can Mean distance from Sun: 730 million km
for as little as £500. provide many hours of viewing pleasure for Mean distance from Earth: 581 million km
Obtaining good images will take a observers using a wide range of astronomical Angular diameter: 31–49 arcseconds
lot of practice and patience. Most areas instruments.
Astronomy Now Yearbook 2007 85