The Moon: First Quadrant (North-east)
T
he First Quadrant is occupied largely by sea. The whole
of the Mare Serenitatis and Mare Crisium are included,
and most of the Mare Tranquillitatis and the darkish Mare
Vaporum, with parts of the Mare Frigoris and Mare
Foecunditatis. There are also some small seas close to the
limb (Smythii, Marginis, Humboldtianum) which are
never easy to observe because they are so foreshortened.
There are also large walled plains close to the limb, such
as Neper and Gauss.
In the south, the Mare Serenitatis is bordered by the
Haemus Mountains, which rise to 2400 metres (7800 feet).
The Alps run along the southern border of the Mare
Frigoris, and here we find the magnificent Alpine Valley,
which is 130 kilometres (80 miles) long and is much
the finest formation of its type on the Moon; a delicate
rill runs along its floor, and there are obscure parallel
and transverse valleys. Mont Blanc, in the Alps, rises to
3500 metres (11,500 feet). Part of the Apennine range
extends into this quadrant, with lofty peaks such as
Mount Bradley and Mount Hadley, both over 4000 metres
(13,000 feet) high. There are several major rill systems
(Ariadaeus, Hyginus, Triesnecker, Ukert, Bürg) and an
area near Arago which is rich in domes. The Apollo 11
astronauts landed in the Mare Tranquillitatis, not far from
Maskelyne, and Apollo 17 came down in the area of
Littrow and the clumps of hills which are called the
Taurus Mountains.Agrippa A fine crater with a central peak and terraced walls.
It forms a notable pair with its slightly smaller neighbour
Godin.
AragoA well-formed crater, with the smaller, bright Manners
to the south-east. Close to Arago is a whole collection of
domes – some of the finest on the Moon; many of them have
summit craterlets.
ArchytasThe most prominent crater on the irregular Mare
Frigoris. It has bright walls and a central peak.
AriadaeusA small crater associated with a major rill system.
The main rill is almost 250 kilometres (150 miles) long, and has
various branches, one of which connects the system with thatof Hyginus– which is curved, and is mainly a craterlet-chain.
Another complex rill system is associated with Triesneckerand
Ukert. All these features are visible with a small telescope
under good conditions.
AristillusThis makes up a group together with Archimedes
(which is shown on the map of the Second Quadrant) and
Autolycus.All three are very prominent. Under high illum-
ination Autolycus is also seen to be the centre of a minor ray-
system.
AristotelesThis and Eudoxusform a prominent pair of walled
plains. Aristoteles has walls rising to 3300 metres (11,000 feet)
above the floor. Atlasand Herculesform another imposing
pair. Atlas has complex floor-detail, while inside Hercules there
is one very bright crater.
BesselThe main formation on the Mare Serenitatis; a well-
formed crater close to a long ray which crosses the mare and
seems to belong to the Tycho system.
BürgA crater with a concave floor; the very large central
peak is crowned by a craterlet (Rømeris another example of
this.) Bürg stands on the edge of a dark plain which is riddled
with rills.
ChallisThis and Mainform a pair of ‘Siamese twins’ – a
phenomenon also found elsewhere, as with Steinheil and Watt
in the Fourth Quadrant.
CleomedesA magnificent enclosure north of Mare Crisium.
The wall is interrupted by one very deep crater, Tralles.
DionysiusOne of several very brilliant small craterlets in the
rough region between Mare Tranquillitatis and Mare Vaporum;
others are Cayley, Whewelland Silberschlag.
EndymionA large enclosure with a darkish floor. It joins the
larger but very deformed De la Rue.
GiojaThe north polar crater – obviously not easy to examine
from Earth. It is well formed, and intrudes into a larger but
low-walled formation.
Julius Caesar This and Boscovichare low-walled, irregular
formations, notable because of their very dark floors.
Le MonnierA fine example of a bay, leading off the Mare
Serenitatis. Only a few mounds of its seaward wall remain.
LinnéA famous formation. It was once suspected of having
changed from a craterlet into a white spot at some time
between 1838 and 1866, but this is certainly untrue. It is a
small, bowl-shaped crater standing on a white patch.
ManiliusA fine crater near Mare Vaporum, with brilliant walls;
it is very prominent around the time of Full Moon. So too is
Menelaus, in the Haemus Mountains.
PicardThis and Peirceare the only prominent craters in the
Mare Crisium.
PliniusA superb crater ‘standing sentinel’ on the strait
between Mare Serenitatis and Mare Tranquillitatis. It has high,
terraced walls; the central structure takes the form of a twin
crater.
PosidoniusA walled plain with low, narrow walls and a floor
crowded with detail. It forms a pair with its smaller neighbour
Chacornac.
ProclusOne of the most brilliant craters on the Moon. It is
the centre of an asymmetrical ray system; two rays border the
Palus Somnii, which has a curiously distinctive tone.
SabineThis and Rittermake up a pair of almost perfect twins –
one of many such pairs on the Moon.
TaruntiusA fine example of a concentric crater. There is a cen-
tral mountain with a summit pit, and a complete inner ring on
the floor. This sort of arrangement is difficult to explain by ran-
dom impact.
ThalesA crater near De la Rue, prominent near Full Moon
because it is a ray-centre.
VitruviusOn the Mare Tranquillitatis, near the peak of Mount
Argaeus. It has bright walls, with a darkish floor and a central
peak.ATLAS OF THE UNIVERSE
Crater Diameter, Lat. °N Long. °E
km
Agrippa 48 4 11
Apollonius 48 5 61
Arago 29 6 21
Archytas 34 59 5
Ariadaeus 15 5 17
Aristillus 56 34 1
Aristoteles 97 50 18
Atlas 69 47 44
Autolycus 36 31 1
Bessel 19 22 18
Bond, W.C. 160 64 3
Boscovich 43 10 11
Bürg 48 45 28
Cassini 58 40 5
Cauchy 13 10 39
Cayley 13 4 15
Challis 56 78 9
Chacornac 48 30 32
Cleomedes 126 27 55
Condorcet 72 12 70
De la Rue 160 67 56
Democritus 37 62 35
Dionysius 19 3 17
Endymion 117 55 55
Eudoxus 64 44 16
Firmicus 56 7 64
Gärtner 101 60 34
Gauss 136 36 80
Geminus 90 36 57
Gioja 35 North polar
Godin 43 2 10
Hercules 72 46 39
Hooke 43 41 55Crater Diameter, Lat. °N Long. °E
km
Hyginus 6 8 6
Jansen 26 14 29
Julius Caesar 71 9 15
Le Monnier 55 26 31
Linné 11 28 12
Littrow 35 22 31
Macrobius 68 21 46
Main 48 81 9
Manilius 36 15 9
Manners 16 5 20
Maskelyne 24 2 30
Mason 31 43 30
Menelaus 32 16 16
Messala 128 39 60
Neper 113 7 83
Peirce 19 18 53
Picard 34 15 55
Plana 39 42 28
Plinius 48 15 24
Posidonius 96 32 30
Proclus 29 16 47
Rømer 37 25 37
Ritter 32 2 19
Sabine 31 2 20
Sulpicius Gallus 13 20 12
Taquet 10 17 19
Taruntius 60 6 48
Thales 39 59 41
Theaetetus 26 37 6
Tralles 48 28 53
Triesnecker 23 4 4
Ukert 23 8 1
Vitruvius 31 18 31SELECTED CRATERS: FIRST QUADRANTC Atl of Univ Phil'03stp 2/4/03 2:54 pm Page 54