Borel is a tiny lunar impact crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 located in the southeast part of Mare Serenitatis

Mare Serenitatis

Mare Serenitatis is a lunar mare that sits just to the east of Mare Imbrium on the Moon.It is located within the Serenitatis basin, which is of the Nectarian epoch. The material surrounding the mare is of the Lower Imbrian epoch, while the mare material is of the Upper Imbrian epoch...

. To the northeast is the crater Le Monnier

Le Monnier (crater)

Le Monnier is the remnant of a lunar crater that has been partly inundated by lava flows. It is located on the eastern edge of Mare Serenitatis, and the western part of the rim is missing so that it now forms a large bay. To the north is the crater Chacornac....

. Borel was previously identified as Le Monnier C before being named by 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...

.

This is a roughly circular, cup-shaped formation with inner floors that slope down to the mid-point of the crater. The interior has a 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 surrounding dark lunar mare

Lunar mare

The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...

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