Australian Sky & Telescope - April 2016__

http://www.skyandtelescope.com.au 59

Albedo features

The Martian surface markings — the dark ‘maria’ and

bright ‘terrae,’ with their picturesque classical names

given by Mars mappers in the late 19th and early 20th

centuries — are merely differences in the average

reflectivity (albedo) of the surface rock, sand and dust.

Windstorms sometimes move the dust, resulting in

both seasonal and long-term changes. Syrtis Major,

the most prominent dark marking, has undergone a

dramatic, long-term widening since the 1950s. It also

shows lesser seasonal changes in width: it tends to be

widest in the northern hemisphere’s mid-summer,

meaning now.

The area around Solis Lacus, sometimes called

the ‘Eye of Mars,’ is notorious for changes in surface

markings. So is the Elysium region.

Clouds and hazes

The Martian atmosphere is ever-changing. Look for

white water-ice clouds and bluish limb hazes. Bright

surface frosts also occur; these are hard to tell from

clouds. As ice in the North Polar Cap sublimates

through the northern summer, the atmosphere gains

ARCADIA

MARE BOREUM

UTOPIA

THARSIS

AMAZONIS

NILIACUS

LACUS

CHRYSE

AURORAE

MARGARI-TIFER SINUS

SINUS SINUS

MERID-

IANI

Protonilus NILOKERAS

MARE ERYTHRAEUM

HELLAS

ELYSIUM SYRTIS MAJORAERIA

ARABIAMOABEDEN

MARE

ACIDALIUM

SIN

USS

ABAEUS

MARE SERPENTIS

LIBYA

Tritonis

Sinus

Hyblaeus

Tithonius

Lacus Noctis

Lacus

Phoenicis

Juventae Lacus

Fons

Solis

Lacus

Clar-

itas

Nix Olympica

(Olympus Mons)

Trivium

Charontis

Gomer

Sinus

Curiosity

Idaeus

Fons

Propontis

Achillis

Fons

Sigeus

Portus

Osidis Pr.

HA

DR

IAT

ICUM

MA

RE

MAREC

IMME

RIU

M

MA

RE

TYR

RHE

NUM

MARES

IRENUM

Tha

umasia

0 °

180 ° 200 ° 220 ° 240 ° 260 ° 280 ° 300 ° 320 ° 340 ° 0 ° 20 ° 40 ° 60 ° 80 ° 100 ° 120 ° 140 ° 160 ° 180 °

180 ° 225 ° 270 ° 315 ° 0 ° 45 ° 90 ° 135 ° 180 °

+20°

+40°

+60°

0 °

+20°

–20° –20°

+40°

+60°

Oxia

Palus

Alcyonius

Nodus Ismenius^ Lacus

–40° –40°

Use this map to identify surface features you see. South is up, and

Martian west longitude is labelled along the bottom. Damian Peach

assembled the map from images he took in 2009– 1 0. The globes,

from Hubble images, are tipped about as much as Mars will appear

this year. Each globe displays the central-meridian longitude that is

directly below it on the map.

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