A3. Zones of Longitude

Letter (Zone Name)

Longitude Range (° E)

Name & Justification

A – Airy

0–15

After crater Airy-0, the prime meridian point.

B – Boreas

15–30

Inspired by Borealis (northern plains).

C – Casius

30–45

After Casius Montes, a range in this sector.

D – Dorsa

45–60

“Dorsa” refers to wrinkle ridges found here.

E – Eos

60–75

Named for Eos Chasma in Valles Marineris region.

F – Fortuna

75–90

After Fortuna Fossae, a network of troughs.

G – Galle

90–105

For Galle Crater (“the happy face” crater).

H – Hebes

105–120

Hebes Chasma, a prominent enclosed canyon.

I – Isidis

120–135

Isidis Planitia impact basin.

J – Juventae

135–150

Juventae Chasma, part of the Valles Marineris.

K – Kasei

150–165

Kasei Valles, large outflow channel system.

L – Libmont

165–180

Libya Montes, hilly highland region.

M – Mangala

180–195 (=-180 to -165)

Mangala Valles, another major channel network.

N – Nili

195–210 (-165 to -150)

Nili Fossae region, fracture system with clay.

O – Olympus

210–225 (-150 to -135)

Olympus Mons, the tallest volcano.

P – Phaethon

225–240 (-135 to -120)

Inspired by Phlegra Montes nearby.

Q – Quince

240–255 (-120 to -105)

A shorter name derived from “Quince Planum”.

R – Rimae

255–270 (-105 to -90)

After Rimae (rilles) around Tharsis.

S – Syriplan

270–285 (-90 to -75)

Syria Planum volcanic plateau.

T – Tharsis

285–300 (-75 to -60)

The huge Tharsis volcanic rise.

U – Utopia

300–315 (-60 to -45)

Utopia Planitia, a large plain.

V – Valles

315–330 (-45 to -30)

From Valles Marineris (broader reference).

W – Warrego

330–345 (-30 to -15)

Warrego Valles channels.

X – Xanthe

345–360 (-15 to 0)

Xanthe Terra, rugged highlands.