science

Mare Tranquillitatis

Mare Tranquillitatis is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mare Tranquillitatis rather than just read about it. In short: Mare Tranquillitatis (Latin for Sea of Tranquillity or Sea of Tranquility) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It contains Tranquility Base, the first location on another celestial body to be visited by humans.

Key takeaways

Mare Tranquillitatis belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mare Tranquillitatis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mare Tranquillitatis from memory before moving on to harder problems.

Reference excerpt

Mare Tranquillitatis (Latin for Sea of Tranquillity or Sea of Tranquility) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It contains Tranquility Base, the first location on another celestial body to be visited by humans. The mare material within the basin consists of basalt formed in the intermediate to young age group of the Upper Imbrian epoch. The surrounding mountains are thought to be of the Lower Imbrian epoch, but the actual basin is probably Pre-Nectarian. The basin has irregular margins and lacks a defined multiple-ringed structure. The irregular topography in and near this basin results from the intersection of the Tranquillitatis, Nectaris, Crisium, Fecunditatis, and Serenitatis basins with two throughgoing rings of the Procellarum basin. Palus Somni, on the northeastern rim of the mare, is filled with the basalt that spilled over from Tranquillitatis. This mare has a slight bluish tint relative to the rest of the Moon and stands out quite well when color is processed and extracted from multiple photographs. The color is likely due to higher metal content in the basaltic soil or rocks. Unlike many other maria, there is no mass concentration (mascon), or gravitational high, in the center of Mare Tranquillitatis. Mascons were identified in the center of other maria (such as Serenitatis or Imbrium) from Doppler tracking of the five Lunar Orbiter spacecraft in 1968. The gravity field was mapped at higher resolution with later orbiters such as Lunar Prospector and GRAIL, which unveiled an irregular pattern.

Naming Mare Tranquillitatis was named in 1651 by astronomers Francesco Grimaldi and Giovanni Battista Riccioli in their lunar map Almagestum novum. Michael van Langren, in his Lumina Austriaca Philippica of 1645, used the name "Mare Belgicum".

Landings

On February 20, 1965, the Ranger 8 spacecraft was deliberately crashed into the Mare Tranquillitatis at 2.6377°N 24.7881°E / 2.6377; 24.7881 (Ranger 8 crash site) after successfully transmitting 7,137 close-range photographs of the Moon in the final 23 minutes of its mission. Surveyor 5 landed in Mare Tranquillitatis on September 11, 1967, after transmitting 19,118 images of the Moon, and was the fifth lunar lander of the uncrewed Surveyor program.

Apollo 11

Mare Tranquillitatis was the landing site for the first crewed landing on the Moon on July 20, 1969, at 20:18 UTC. After astronauts Neil Armstrong and Buzz Aldrin made a soft landing in the Apollo 11 Lunar Module Eagle, Armstrong told flight controllers on Earth, "Houston, Tranquility Base here. The Eagle has landed." The landing area at 0.8°N 23.5°E / 0.8; 23.5 (Tranquility Base) has been designated Statio Tranquillitatis after Armstrong's name for it. Three small craters to the north of the base have been named Aldrin, Collins, and Armstrong in honor of the Apollo 11 crew. Apollo 11 landed at 00.67408°N 23.47297°E / 00.67408; 23.47297 (Apollo 11 landing site).

Bays Along the periphery of the mare are several bay-shaped features that have been given names: Sinus Amoris, Sinus Asperitatis, Sinus Concordiae, and Sinus Honoris.

Views

These are three views of Mare Tranquillitatis on the Moon, taken by the mapping camera of the Apollo 17 mission in 1972, facing south-southwest from an average altitude of 111 km on Revolution 36 of the mission. At the left is the east side of Mare Tranquillitatis, with the craters Franz (bottom right), Lyell (dark floor, right of center), and Taruntius (upper left). The "bay" of dark mare (basalt) at left is Sinus Concordiae, with "islands" of older, light highland material. At the right is the crater Cauchy, which lies between the Rupes Cauchy and Cauchy rille. The center photo shows the central mare with craters Vitruvius (lower right) and Gardner (bottom center). At the horizon are lighter highlands at the southern margin of the mare, near the Apollo 11 landing site. The crater Jansen is visible at the edges of both the center and right photos. The right photo shows the western mare, with the craters Dawes (lower left) and the large Plinius (43 km diameter), with the Plinius Rilles in the foreground. These photos were taken within minutes of each other as the command module America orbited the Moon. The Sun elevation drops from 46 degrees at left to 30 degrees at right.

Gallery

In popular culture Sea of Tranquility, a 2022 book by Emily St. John Mandel

See also Lists of astronomical objects Volcanism on the Moon

References

Illustrations

Worked examples

Example 1 — a first encounter with Mare Tranquillitatis

Start with the simplest possible case. Write down what Mare Tranquillitatis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mare Tranquillitatis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mare Tranquillitatis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mare Tranquillitatis

In research: Mare Tranquillitatis appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mare Tranquillitatis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mare Tranquillitatis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Apollo 11, Imbrian, LQ12 quadrangle, so understanding it makes those chapters shorter.
In everyday life: Look for Mare Tranquillitatis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mare Tranquillitatis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mare Tranquillitatis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mare Tranquillitatis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mare Tranquillitatis in simple terms?

Why does Mare Tranquillitatis matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mare Tranquillitatis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mare Tranquillitatis.