http://www.skyandtelescope.com.au 55SyrtisMajorwerehadthroughout
lateJuneandintoearlyJuly.The
South Polar Cap, hidden from view
by its seasonal polar hood of fog
andcloudsinMay,becamevisible
bythestartofJuly,thoughittoo
wasstreakedbydust,producing
adimmedappearancecompared
to its usual brilliant white. The
Tharsisvolcanoes,including
Olympus Mons, each stood out as
readily discernible dark spots from
the monochromatic surroundings
below them.
By early July, most observers
hadwrittenofftheplanet’s2018
opposition, steeling themselves
fordisappointingviewsofabright
butbland,unadornedball.But
fortunately, things quickly began to
turn around.
Inmid-July,reportsofaclearing
atmosphere began spreading
throughout the observing
community.Whiletheplanet
displayedadistinctlyreduced
contrast overall, familiar albedo
features,includingSolisLacus
and the small albedo extensions
from Mare Cimmerium known as
GomerSinus,werereadilyvisible.
PlanetaryimagerDamianPeach
noted“adarkalbedofeatureacross
Phasis-Daedalia [part of Solis
Lacus] which was not visible before
thestorm(thoughhasappeared
followingdusteventsinthepast).”
Both Peach and French amateur
Christophe Pellier spotted several
smallstormswithinSolisLacus
inthelastweekofthemonthas
opposition approached, though
fortunatelynoneoftheselasted
morethanadayortwo.
Following opposition on
July 27 and closest approach a
fewdayslater,theRedPlanet’s
atmosphere slowly continued to
clear, producing detailed (though
low-contrast) views for dedicated
andcasualplanetaryobservers
alike. Additional subtle changes of
albedo features have been observed,
butnoneasdrasticasthosethat
occurred following the great duststorm of 1956, which erased the
large, dark feature known as Thoth-
Nepenthes.
Some minor global changes have
been recorded following the storm.
A general reduction in contrast
implies that some light dust remains
suspended in the upper atmosphere.
Additionally, the thin white clouds of
water vapour that treated observers
each apparition over the past 15
years have been completely absent so
far in the latter half of 2018.
The storm was unusual in several
respects compared to events of the
past. As mentioned earlier, it started
in a region that, while known for
producing small regional storms
throughout the past decade, had not
generated a storm of this magnitude
to date. Additionally, the storm grew
quickly and spread mostly across
the northern hemisphere but never
completely obscured the entire
planet. While classified as a global
dust storm, it didn’t become quite
as opaque as the last big storm that
scuttled the tail-end of the 2001
apparition.
And just a little more than two
months after erupting into view, it
was mostly gone. The planet seemed
to give observers a reprieve, with
good views of major albedo markings
returning just following opposition.
Mars is one of the most
interesting planets from an
observational standpoint. As the
most Earthlike planet, it displays
weather similar to ours. And it’s the
only terrestrial planet besides Earth
on which amateurs can easily see
the surface and recognise known
features. For many of us, tracking
the development of regional dust
storms, for example, or watching
for water vapour clouds along the
planet’s limb and clinging to the
slopes of the Tharsis volcanoes
makes the planet particularly
attractive. So from that point of
view, the 2018 apparition wasn’t a
complete write-off for observers — in
fact, it stands out as one of the more
exciting ones in recent memory.WBy the time
of opposition,
the dust was
noticeably settling
out of the Martian
atmosphere.
This produced
low-contrast but
recognisable
albedo features.
This image by
Anthony Wesley
is very similar to
the view at the
eyepiece.WDust filled the
gigantic canyon
system Valles
Marineris on the
morning of June
13, enabling Darren
Ellemor to record
this enigmatic
feature with just a
15-cm Schmidt-
Cassegrain.WIn early August,
observers began to
recognise changes
in the planet’s
albedo features.
The dark marking
in the Solis Lacus
region in this
image is a feature
sometimes seen
after a large dust
storm, as noted in
the text.WThis image
shows a small but
bright dust storm
captured on the
morning of May 31
by John Boudreau
using a 36-cm Dall-
Kirkham reflector.BOTTOM IMAGE OF MARS: DAMIAN PEACH / CHILESCOPE