THE SOLAR SYSTEM
H
ighlands occupy a large part of the Third Quadrant,
though part of the huge Mare Nubium is included
together with the whole of the Mare Humorum. There are
some high mountains on the limb, and a very small part of
the Mare Orientale can be seen under really favourable
libration; otherwise the main mountains are those of the
small but prominent Riphaean range, on the Mare Nubium.
Of course the most prominent crater is Tycho, whose rays
dominate the entire surface around the time of Full Moon.
This quadrant also includes two of the most prominent
chains of walled plains, those of Ptolemaeus and Walter;
the dark-floored Grimaldi and Riccioli; the celebrated
plateau Wargentin, and the inappropriately named Straight
Wall. The most important rill systems are those of Sirsalis,
Ramsden, Hippalus and Mersenius.SELECTED CRATERS: THIRD QUADRANT
Crater Diameter, Lat. °S Long. °W
km
Agatharchides 48 20 31
Alpetragius 43 16 4
Alphonsus 129 13 3
Arzachel 97 18 2
Bailly 294 66 65
Bayer 52 51 35
Bettinus 66 63 45
Billy 42 14 50
Birt 18 22 9
Blancanus 92 64 21
Bonpland 58 8 17
Bullialdus 50 21 22
Byrgius 64 25 65
Campanus 38 28 28
Capuanus 56 34 26
Casatus 104 75 35
Clavius 232 56 14
Crüger 48 17 67
Cysatus 47 66 7
Damoiseau 35 5 61
Darwin 130 20 69
Davy 32 12 8
Deslandres 186 32 6
Doppelmayer 68 28 41
Euclides 12 7 29
Flammarion 72 3 4
Flamsteed 19 5 44
Fra Mauro 81 6 17
Gassendi 89 18 40
Gauricus 64 34 12
Grimaldi 193 6 68
Gruemberger 87 68 10
Guericke 53 12 14
Hainzel 97 41 34
Hansteen 36 11 52
Heinsius 72 39 18
Hell 31 32 8
Herigonius 16 13 34
Herschel 45 6 2
Hesiodus 45 29 16
Hippalus 61 25 30
Inghirami 97 48 70
Kies 42 26 23
Kircher 74 67 45
Klaproth 119 70 26
Lagrange 165 33 72Crater Diameter, Lat. °S Long. °W
km
Lalande 24 4 8
Lassell 23 16 8
Le Gentil 140 73 80
Letronne 113 10 43
Lexell 63 36 4
Lohrmann 45 1 67
Longomontanus 145 50 21
Maginus 177 50 6
Mercator 38 29 26
Mersenius 72 21 49
Moretus 105 70 8
Mösting 26 1 6
Nasireddin 48 41 0
Newton 113 78 20
Nicollet 15 22 12
Orontius 84 40 4
Parry 42 8 16
Phocylides 97 54 58
Piazzi 90 36 68
Pictet 48 43 7
Pitatus 86 30 14
Ptolemaeus 148 9 3
Purbach 120 25 2
Regiomantanus 129 105 28 0
Riccioli 160 3 75
Rocca 97 15 72
Saussure 50 43 4
Scheiner 113 60 28
Schickard 202 44 54
Schiller 180 97 52 39
Segner 74 59 48
Short 70 76 5
Sirsalis 32 13 60
Thebit 60 22 4
Tycho 84 43 11
Vieta 52 29 57
Vitello 38 30 38
Walter 129 33 1
Wargentin 89 50 60
Weigel 55 58 39
Wichmann 13 8 38
Wilhelm I 97 43 20
Wilson 74 69 33
Wurzelbauer 80 34 16
Zucchius 63 61 50
Zupus 26 17 52BaillyOne of the largest walled plains on the Moon, but unfor-
tunately very foreshortened. It has complex floor detail, and
has been described as ‘a field of ruins’.
BillyThis and Crügerare well-formed, and notable because of
their very dark floors, which make them easily identifiable.
BullialdusA particularly fine crater, with massive walls and cen-
tral peak. It is not unlike Copernicus in structure, though it
is not a ray-centre.
CapuanusA well-formed crater, with a darkish floor upon
which there is a whole collection of domes.
ClaviusA vast walled plain, with walls rising to over 4000
metres (13,000 feet). The north-western walls are broken by a
large crater, Porter, and there is a chain of craters arranged
in an arc across the floor. Near the terminator, Clavius can be
seen with the naked eye.
EuclidesA small crater near the Riphæan Mountains, easy to
find because it is surrounded by a bright nimbus.
Fra Mauro One of a group of low-walled, reduced formations
on the Mare Nubium (the others are Bonpland, Parryand
Guericke). Apollo 14 landed near here.
GassendiA grand crater on the north border of the Mare
Humorum. The wall has been reduced in places, and is broken
in the north by a large crater. There is a rill-system on the
floor, and TLP have been seen here. North of Gassendi is a
large bay, Letronne.
GrimaldiThe darkest formation on the Moon. The walls are
discontinuous, but contain peaks rising to 2500 metres (8000
feet). Adjoining it is Riccioli, which is less regular but has one
patch on its floor almost as dark as any part of Grimaldi.
HippalusA fine bay in the Mare Humorum, associated with
a system of rills. Like another similar bay, Doppelmayer,
Hippalus has the remnant of a central-peak.
KiesA low-walled crater on the Mare Nubium, with a flooded
floor. Near it lies a large dome with a summit craterlet.
MaginusA very large formation with irregular walls; other
large walled plains of the same type in the area are
Longomontanusand Wilhelm I.Maginus is curiously obscure
around the time of Full Moon.
MercatorThis and Campanusform a notable pair. They are
alike in form and shape, but Mercator has the darker floor.
MerseniusA prominent walled plain closely west of the Mare
Humorum, associated with a fine system of rills.
MoretusA very deep formation in the southern uplands, with a
particularly fine central peak.
NewtonOne of the deepest formations on the Moon, but
never well seen because it is so close to the limb.
PitatusThis has been described as a ‘lagoon’ on the coast
of the Mare Nubium. It has a dark floor and a low central peak.
A pass connects it with the neighbour Hesiodus, which is
associated with a long rill extending south-westwards.
PtolemaeusThe largest member of the most imposing line of
walled plains on the Moon. Ptolemaeus has a flattish floor withone large crater, Ammonius; Alphonsushas a central peak and
a system of rills on its floor; Arzachelis smaller, but with
higher walls and a more developed central peak. Several TLP
have been seen in Alphonsus. Nearby is Alpetragius, with
regular walls and a central peak crowned by a craterlet.
PurbachOne of a line of three major walled plains on the edge
of the Mare Nubium. The other members are Walter, which
has fairly regular walls, and Regiomontanus, which gives the
impression of having been squashed between Walter to the
south and Purbach to the north.
ScheinerThis and Blancanusare two large, important walled
plains close to Clavius.
SchickardOne of the major walled plains on the Moon. The
walls are rather low and irregular; the floor contains some
darkish patches as well as various hills and craterlets.
SchillerA compound formation, produced by the fusion of two
old rings.
SirsalisOne of ‘Siamese twins’ with its neighbour. It is
associated with a long and very prominent rill.
ThebitNear the Straight Wall, the crater is broken by Thebit A,
which is in turn broken by Thebit F.
TychoThe great ray-crater. Its bright walls make it prominent
even in low illumination. Near Full Moon it is clear the rays
come tangentially from the walls rather than from the centre.C Atl of Univ Phil'03stp 2/4/03 2:55 pm Page 59