Gale is a crater, and probable dry lake, at 5°24′S 137°48′E / 5.4°S 137.8°E / -5.4; 137.8 in the northwestern part of the Aeolis quadrangle on Mars. It is 154 km (96 mi) in diameter and estimated to be about 3.5–3.8 billion years old. The crater was named after Walter Frederick Gale, an amateur astronomer from Sydney, Australia, who observed Mars in the late 19th century. Aeolis Mons, also known as Mount Sharp, is a mountain in the center of Gale and rises 5.5 km (18,000 ft) high. Aeolis Palus is the plain between the northern wall of Gale and the northern foothills of Aeolis Mons. Peace Vallis, a nearby outflow channel, 'flows' down from the hills to the Aeolis Palus below and seems to have been carved by flowing water. Several lines of evidence suggest that a lake existed inside Gale shortly after the formation of the crater.

The NASA Mars rover Curiosity, of the Mars Science Laboratory (MSL) mission, landed in "Yellowknife" Quad 51 of Aeolis Palus in Gale at 05:32 UTC August 6, 2012. NASA named the landing location Bradbury Landing on August 22, 2012. Curiosity is exploring Aeolis Mons and surrounding areas.^[when?]

Gale, named for Walter F. Gale (1865–1945), an amateur astronomer from Australia, spans 154 km (96 mi) in diameter and holds a mountain, Aeolis Mons (informally named "Mount Sharp" to pay tribute to geologist Robert P. Sharp) rising 18,000 ft (5,500 m) from the crater floor, higher than Mount Rainier rises above Seattle. Gale is roughly the size of Connecticut and Rhode Island.

The crater formed when an asteroid or comet hit Mars in its early history, about 3.5 to 3.8 billion years ago. The impactor punched a hole in the terrain, and the subsequent explosion ejected rocks and soil that landed around the crater. Layering in the central mound (Aeolis Mons) suggests it is the surviving remnant of an extensive sequence of deposits. Some scientists believe the crater filled in with sediments and, over time, the relentless Martian winds carved Aeolis Mons, which today rises about 5.5 km (3.4 mi) above the floor of Gale—three times higher than the Grand Canyon is deep.

At 10:32 p.m. PDT on August 5, 2012 (1:32 a.m. EDT on August 6, 2012), the Mars Science Laboratory rover Curiosity landed on Mars at 4°30′S 137°24′E / 4.5°S 137.4°E / -4.5; 137.4, at the foot of the layered mountain inside Gale. Curiosity landed within a landing ellipse approximately 7 km (4.3 mi) by 20 km (12 mi). The landing ellipse is about 4,400 m (14,400 ft) below Martian "sea level" (defined as the average elevation around the equator). The expected near-surface atmospheric temperatures at the landing site during Curiosity's primary mission (1 Martian year or 687 Earth days) are from −90 to 0 °C (−130 to 32 °F).

Scientists chose Gale as the landing site for Curiosity because it has many signs that water was present over its history. The crater's geology is notable for containing both clays and sulfate minerals, which form in water under different conditions and may also preserve signs of past life. The history of water at Gale, as recorded in its rocks, is giving Curiosity many clues to study as it pieces together whether Mars ever could have been a habitat for microbes. Gale contains a number of fans and deltas that provide information about lake levels in the past, including: Pancake Delta, Western Delta, Farah Vallis delta and the Peace Vallis Fan.

Orbital THEMIS and topography data, plus visible and near-infrared images, were used to make a geological map of the crater. CRISM data indicated the lower bench unit was composed of interstratified clay and sulfates. Curiosity explored the stratigraphy of the crater consisting of the Bradbury Group and the overlying Mount Sharp Group. Formations within the Bradbury Group include the Yellowknife and Kimberley, while the Murray Formation is at the base of the Mount Sharp Group. The Bradbury Group consists of fluvial conglomerates, cross-bedded sandstones, and mudstones reflecting a basaltic provenance. Sandstone clinoforms indicate deltaic deposits. The Murray Formation is a laminated mudstone overlain by a cross-bedded or clinoform sandstone, though in places the base is a conglomerate. Thus, the formation is interpreted to have been deposited in a lacustrine environment adjacent to a fluvial-deltaic one. The Murray Formation is overlain by clay and sulfate-bearing strata.

An unusual feature of Gale is an enormous mound of "sedimentary debris" around its central peak, officially named Aeolis Mons (popularly known as "Mount Sharp") rising 5.5 km (18,000 ft) above the northern crater floor and 4.5 km (15,000 ft) above the southern crater floor—slightly taller than the southern rim of the crater itself. The mound is composed of layered material and may have been laid down over a period of around 2 billion years. The origin of this mound is not known with certainty, but research suggests it is the eroded remnant of sedimentary layers that once filled the crater completely, possibly originally deposited on a lakebed. Evidence of fluvial activity was observed early on in the mission at the Shaler outcrop (first observed on Sol 120, investigated extensively between Sols 309-324). Observations made by the rover Curiosity at the Pahrump Hills strongly support the lake hypothesis: sedimentary facies including sub mm-scale horizontally-laminated mudstones, with interbedded fluvial crossbeds are representative of sediments which accumulate in lakes, or on the margins of lakes which grow and contract in response to lake-level. These lake-bed mudstones are referred to as the Murray Formation, and form a significant amount of the Mount Sharp group. The Siccar Point group (named after the famous unconformity at Siccar Point) overlies the Mount Sharp group, and the two units are separated by a major unconformity which dips toward the North. At present, the Stimson formation is the only stratigraphic unit within the Siccar Point group which has been investigated in-detail by Curiosity. The Stimson formation represents the preserved expression of a dry aeolian dune field, where sediment was transported towards the north, or northeast by palaeowinds within the crater. In the Emerson plateau area (from Marias Pass, to East Glacier), the outcrops are characterised predominantly by simple cross-sets, deposited by simple sinuous-crested dunes, with heights up to ~10 m. To the south, at the Murray buttes, the outcrop are characterised by compound cross-sets, with a hierarchy of bounding surfaces migration of small dunes superimposed on the lee-slope of a large dune known as a "draa". These draas have estimates heights of ~40 m, and migrated toward the north, while superimposed dunes migrated toward the east-northeast. Further to the south, at the Greenheugh pediment, compound and simple cross-sets consistent with aeolian depositional processes have been observed in the pediment capping unit. Observations made during the ascent of the Greenheugh pediment between Sols 2665-2734 demonstrated that the pediment capping unit has sedimentary textures, facies and architecture that are consistent with the rest of the Stimson formation. Furthermore, analysis of sedimentary facies and architecture provided evidence which indicates fluctuating wind directions, from a seasonal temporal scale - recorded by interstratified windripple and avalanche strata, through to millennial time scales recorded by reversal of the sediment transport direction. These wind reversals suggest variable and changeable atmospheric circulation during this time.