SkyandTelescope.com March 2014 55Sean Walker
Every Martian apparition, Sky & Telescope imaging editor Sean Walker
drops all other observing projects to concentrate on the Red Planet.rift should be visible in telescopes 6 inches or larger and
will look like a dark inner ring dividing the icy crescent
from the main NPC.Partly Cloudy
Clouds have been prevalent throughout the last several
apparitions, and although they are most easily detected by
planetary imagers using color fi lters, observers can enjoy
them too. As the NPC recedes, its ices sublimate into the
planet’s tenuous atmosphere, producing thin clouds that
are often visible above the planet’s equatorial regions.
About this time, the well-known “W” cloud formation often
clings to the fl anks of the large volcanoes in the Tharsis-
Amazonis region. These clouds can sometimes appear so
bright that you might have diffi culty determining which
white spot is the NPC and which is the cloud complex.
Morning clouds and frost can sometimes settle in the
broad, low plains of this region, making the giant Tharsis
volcanoes Arsia Mons, Pavonis Mons, and Ascraeus
Mons, as well as nearby Olympus Mons, appear as dark
spots above the bright plains.
In the southern hemisphere, a bright cloud often fi lls
the great Hellas impact basin; don’t mistake this for a
glimpse of the South Polar Cap.Dust Storms
In the months leading up to opposition, there’s always the
chance that changing weather patterns will kick up large
dust storms and block parts of the surface from view.
Dust storms can spring up overnight and often appear as
small, brightish, yellow clouds. They are most prominent
when hovering over dark albedo features.
Historically, dust storms have often been spotted in
Hellas, Elysium, Chryse, and Solis Lacus. During late
October 2005, a large dust storm sprang up in Chryse and
then spilled into the deep chasms within Aurorae Sinus.
Because of its high albedo compared with the terrain,
this storm had the rare eff ect of making parts of gigantic
Valles Marineris visible for a few weeks from Earth in
amateur telescopes.
Dust storms can arise almost anywhere on Mars and
occasionally encircle the entire globe, obscuring the whole
surface. Although global dust events can put a damper on
observations, it’s exciting to watch these massive wind-
driven storms envelop the planet within a few days.Changing Albedo Features
The dark albedo features of Mars have also experienced
long-term changes over the years. Dark markings within
Solis Lacus have come and gone within the last decade.
Additionally, a dark feature at roughly 230°W known as
Hyblaeus has also expanded and receded throughout the
past quarter century.Perhaps the largest recent albedo change occurred in
the 1960s. Around that time, a large complex of albedo
features connecting Syrtis Major to Utopia, located at
about 270°W and known as Thoth-Nepenthes, literally
disappeared. Today, only the small dark feature known as
Alcyonius Nodus remains.
At about the same time as the disappearance of Thoth-
Nepenthes, the northernmost tip of Syrtis Major changed
from a distinctly pointed feature to the rounded end that
today resembles the southern tip of Africa.
Assuming the Red Planet isn’t immersed in a globe-
spanning dust storm, a dynamic, changing world beckons
observers as it draws relatively close for a few brief
months every 26 months. Let’s see what surprises it has
in store for us this year. ✦S&T: DENNIS DI CICCOMarch 162074For key dates, yellow dots indicate which part of the Moon’s limb is tipped
the most toward Earth by libration under favorable illumination.NEW MOON
March 1, 8:00 UTFIRST QUARTER
March 8, 13:27 UT
FULL MOON
March 16, 17:08 UT
LAST QUARTER
March 24, 1:46 UT
NEW MOON
March 30, 18:45 UTPhasesLibrations
Mare Smythii March 4
Rayleigh (crater) March 7
Repsold (crater) March 16
Lacus Veris March 20Distances
Apogee March 11, 20h UT
251,882 miles diam. 29′ 29 ′′
Perigee March 27, 19h UT
227,238 miles diam. 32′ 41 ′′The Moon • March 2014
ETSS layout.indd 55 12/23/13 11:35 AM