Transcript The Moon and its surface

The Moon and its Surface
This image shows the Moon rising in the east. The phase is
almost full. The orange/red colour is an effect caused by the
Earth’s atmosphere. The giant rayed craters (Tycho and
Copernicus among others) are clearly visible.
The most notable features of the lunar surface are the (darker)
seas (maria) and highlands (terrae); the maria give the Moon its
familiar ‘Man in the Moon’ face when full!
The maria are in fact giant basins that have been filled by lava;
they are younger than the rest of the Moon’s surface.
The maria cover about 15% of the lunar surface. The ‘far side’ of
the Moon is almost devoid of maria.
The entire surface of the Moon is covered
in craters that range is size from about
one metre across to 100 km across. They
are believed to be impact craters (though
some may be volcanic in origin).
The larger craters have light-coloured
‘rays’ of material that was ejected during
their formation; these are best seen at
full moon when the Moon is fully
illuminated by the Sun.
The maria have exotic names such as the
Ocean of Storms and the Sea of Crises;
the first manned landing in 1969 took
place in the Sea of Tranquillity.
There are also mountain ranges on
the Moon, named (not quite as
imaginatively) after ranges on Earth
such as the Alps and Pyrenees.
July 1969 – the first manned
landing on the lunar surface
by Apollo 11 astronauts.
The surface of the Moon has other notable
features, in particular:
• rilles
• wrinkle ridges
• mascons
• domes
You might need to describe each of these features surface and
explain their likely origin.
Rilles are narrow trenches up to 5 km
wide x 500 m deep (from the German
word for ‘groove’ or ‘trench’.
2 types:
• straight (probably faults in the lunar
crust)
• sinuous (collapses lava tubes or
channels)
Wrinkle Ridges can be up to
200 m high and 100’s of km long.
When the young lunar lava forming
the maria cooled and contracted,
it formed these ridges (like ‘tucks’
in a carpet).
Mascon is short for mass concentration.
These circular areas, up to 200 km in
diameter are regions where the pull of
gravity on the Moon is slightly greater
than usual.
This image shows the
gravity field at Sea of
Tranquility. The upper
segment represents the
topography- a fairly flat low
region-and the lower
segment shows the
corresponding strong gravity
field. This is a mascon.
They are believed to have formed when
large meteoroids struck the lunar surface,
removing the lighter crust, and denser
(and so more massive) magma was forced
upwards to the surface.
Domes are small swellings up to 25 km
in diameter (like ‘blisters’) found mainly
near the edges of maria.
They could have been formed by
relatively thick lava solidifying in an
uneven manner OR by an upsurge of
moulten rock causing the surface to rise
upwards.
You now might like to explore the lunar features in
more detail or simply wonder at the contrast
between the dark maria and the highland regions.