Sinus Roris is an extension of the northern edge of Oceanus Procellarum

Oceanus Procellarum

Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Earth's Moon. Its name derives from the old superstition that its appearance during the second quarter heralded bad weather...

 on the Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. The IAU

International Astronomical Union

The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...

-defined selenographic coordinates

Selenographic coordinates

Selenographic coordinates are used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth...

 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 the craters Markov

Markov (crater)

Markov is a lunar impact crater that is located in the northwestern part of the moon’s near side, in the Sinus Roris region of the Oceanus Procellarum. It lies to the south of the crater Oenopides, and is connected to the continental region to the north by ridges along the northern rim.The rim of...

 and Oenopides

Oenopides (crater)

Oenopides is a lunar crater that is located near the northwestern limb of the Moon, and so appears foreshortened when viewed from the Earth. This formation lies due south of the prominent crater Pythagoras, and is attached to the southwest rim of Babbage E. The southwest rim of Oenopides is part of...

, and to the north by Babbage

Babbage (crater)

Babbage is an ancient lunar crater that is located near the northwest limb of the Moon, named after Charles Babbage. It is attached to the southeastern rim of the prominent crater Pythagoras...

 and South

South (lunar crater)

South is a large lunar crater that is located in the northwest part of the Moon. Most of the southern wall of this crater is joined to the Sinus Roris bay of the Oceanus Procellarum, with the southeast rim facing Mare Frigoris. Attached to the northwest of the formation is the larger walled plain...

. At the eastern edge it joins the Mare Frigoris

Mare Frigoris

Mare Frigoris is a lunar mare located just north of Mare Imbrium, and stretches east to north of Mare Serenitatis. The mare is in the outer rings of the Procellarum basin...

.

Many selenographers

Selenography

Selenography is the study of the surface and physical features of the Moon. Historically, the principal concern of selenographists was the mapping and naming of the lunar maria, craters, mountain ranges, and other various features...

 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 range out as far as the craters Gerard

Gerard (crater)

Gerard is a lunar crater that lies along the western edge of the Oceanus Procellarum near the northwest limb of the Moon's near side. It is located to the north-northwest of the crater von Braun, and northeast of Bunsen...

 and Repsold

Repsold (crater)

Repsold is a lunar crater that is located at the western end of the Oceanus Procellarum. It lies to the northeast of the crater Galvani and southeast of the walled plain Volta. Due to its proximity to the northwestern limb of the Moon, this crater appears highly foreshortened when viewed from the...

 to the west, Harpalus

Harpalus (crater)

Harpalus is a young lunar impact crater that lies on the Mare Frigoris, at the eastern edge of the Sinus Roris. To the southeast at the edge of the mare is the small crater Foucault, and to the northwest on the opposite edge is the walled plain named South....

 to the east, and as far south as 44° N latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

, approaching Mons Rümker

Mons Rümker

Mons Rümker is an isolated volcanic formation that is located in the northwest part of the Moon's near side, at selenographic coordinates 40.8° N, 58.1° W. The feature forms a large, elevated mound in the northern part of the Oceanus Procellarum. The mound has a diameter of 70 kilometres, and...

.

The area where the official coordinates place this bay has a generally higher albedo

Albedo

Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

 than the mare to the south, most likely due to deposits of ejecta from impacts to the north.

Arthur C Clarke's

Arthur C. Clarke

Sir Arthur Charles Clarke, CBE, FRAS was a British science fiction author, inventor, and futurist, famous for his short stories and novels, among them 2001: A Space Odyssey, and as a host and commentator in the British television series Mysterious World. For many years, Robert A. Heinlein,...

 novel A Fall of Moondust

A Fall of Moondust

A Fall of Moondust is a hard science fiction novel by Arthur C. Clarke, first published in 1961. It was nominated for a Hugo Award for Best Novel, and was the first science fiction novel selected to become a Reader's Digest Condensed Book....

is set in a fictional "Sea of Thirst" located within Sinus Roris.

USGS lunar map showing Sinus Roris