Oceanus Procellarum
Oceanus Procellarum,
Latin for "Ocean of Storms", is a vast
lunar mare on the western edge of the near side of
Earth's
Moon. Its name derives from the old superstition that its appearance during the
second quarter heralded bad weather. Procellarum is the largest of the lunar maria, stretching 2500 kilometers across its north-south axis and covering roughly
4,000,000 km2.
Like all lunar maria, Oceanus Procellarum was formed by ancient
basaltic flood
volcanic eruptions that covered the region in a thick, nearly flat layer of solidified
magma. Unlike the other lunar maria, however, Procellarum is not contained within a single well-defined impact basin (although much of it is within the
Procellarum Basin). Around its edges lie many minor bays and seas, including
Mare Nubium and
Mare Humorum to the south. To the northeast, Oceanus Procellarum is separated from
Mare Imbrium by the
Carpathian Mountains.
The
unmanned lunar probes
Surveyor 1,
Surveyor 3,
Luna 9 and
Luna 13 landed in Oceanus Procellarum.
Apollo 12 also landed in Oceanus Procellarum.
Sinus Roris
A northward extension of the Oceanus Procellarum has been given the
latin name for "Bay of Dew". The
IAU-defined selenographic
coordinates of this bay are 54.0° N, 56.6° W, and the diameter is 202 km.
The borders of this feature are somewhat indistinct. The bay proper is framed along the western edge by
Markov and
Oenopides craters, and to the north by
Babbage and
South craters. At the eastern edge it joins the
Mare Frigoris.
Many selenographers have taken liberties with the dimensions of Sinus Roris. Lunar maps often indicate a much larger region for this bay than the official dimensions. These can ranging out as far as the
Gerard and
Repsold craters to the west,
Harpalus crater to the east, and as far south as 44° N
latitude, approaching
Mons Rümker.
The area where the official coordinates place this bay has a generally higher
albedo than the mare to the south, most likely due to deposits of
ejecta from impacts to the north.
