science

Ptolemaeus (lunar crater)

Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) rather than just read about it. In short: Ptolemaeus is an ancient lunar impact crater close to the center of the near side, named for Claudius Ptolemy, the Greco-Roman writer, mathematician, astronomer, geographer and astrologer. It measures approximately 154 kilometers in diameter.

Key takeaways

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

Reference excerpt

Ptolemaeus is an ancient lunar impact crater close to the center of the near side, named for Claudius Ptolemy, the Greco-Roman writer, mathematician, astronomer, geographer and astrologer. It measures approximately 154 kilometers in diameter. T. W. Webb called it "a magnificent lake, whose surface at sunrise or sunset is occasionally seen all roughened with ridges like waves".

Description To the south-southwest, Ptolemaeus is joined to the rim of the crater Alphonsus by a section of rugged, irregular terrain, and these form a prominent chain with Arzachel to the south. To the southeast is Albategnius and to the north is the smaller but well-defined Herschel.

The features of Ptolemaeus are highlighted when the Sun is at low angles during the first and last quarter. At full Moon the Sun is directly overhead and the crater contours become more difficult to discern. The crater has a low, irregular outer rim that is heavily worn and impacted with multiple smaller craters. The rim has a discernibly polygonal shape, although overall it remains circular. The largest of the peaks along the rim, designated Ptolemaeus Gamma (γ), has an altitude of 2.9 km and is located along the northwest rim. The crater has no central peak, a lava-flooded floor, and lacks a ray system. Impact sites of this form are often termed walled plains, due to their resemblance to the maria. The somewhat dark-hued floor of Ptolemaeus is notable for several ghost craters, formed where lava has covered a pre-existing crater. These leave only a slight rise where the rim existed, and are difficult to detect except at low angles of sunlight. There are also multiple smaller craters across the floor surface, most notably Ammonius in the northeastern quadrant. On either side of this crater are linear, irregular gashes in the lunar surface, forming valley-like features. These features are approximately parallel to each other and radiate from the direction of Mare Imbrium to the north-northwest.

Satellite craters By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Ptolemaeus.

The following crater has been renamed by the IAU.

Ptolemaeus A — See Ammonius.

See also Ptolemaeus (Martian crater) 4001 Ptolemaeus

References

Sources

External links

Ptolemaeus at The Moon Wiki I-556 Ptolemaeus - USGS Geological Atlas of the Moon, 1966 Wood, Chuck (March 3, 2004). "Ptolemaic Sunset". Lunar Photo of the Day. Wood, Chuck (March 4, 2004). "Ptolemaic Peak Heights". Lunar Photo of the Day. Wood, Chuck (May 15, 2004). "The Golden Triad". Lunar Photo of the Day. Archived from the original on May 30, 2018. Retrieved September 3, 2017. Wood, Chuck (August 12, 2004). "Ptolemy's Strange Floor". Lunar Photo of the Day. Wood, Chuck (October 31, 2004). "Sunrise and Sunset on the Triade". Lunar Photo of the Day. Archived from the original on October 14, 2017. Retrieved October 14, 2017. - one of three craters making up a Triad - that includes Ptolemaeus Wood, Chuck (April 8, 2005). "Cups & Saucers". Lunar Photo of the Day. Archived from the original on May 30, 2018. Retrieved September 3, 2017. Wood, Chuck (2006-04-06). "Micro-Topo". Lunar Photo of the Day. Retrieved 2006-07-21. Wood, Chuck (November 27, 2006). "A Long Line in a Clutter of Magnificence". Lunar Photo of the Day. Archived from the original on June 14, 2011. NASA Astronomy Picture of the Day: Ptolemaeus, Alphonsus and Arzachel (9 February 2007) Wood, Chuck (May 15, 2008). "Unfamiliar Territory". Lunar Photo of the Day. Wood, Chuck (January 28, 2009). "Ramparts". Lunar Photo of the Day. Wood, Chuck (September 4, 2014). "Nessie". Lunar Photo of the Day.

Illustrations

Worked examples

Example 1 — a first encounter with Ptolemaeus (lunar crater)

Start with the simplest possible case. Write down what Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater)

In research: Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) 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: Ptolemaeus (lunar crater) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Impact craters on the Moon, LQ19 quadrangle, Ptolemy, so understanding it makes those chapters shorter.
In everyday life: Look for Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ptolemaeus (lunar crater) in simple terms?

Why does Ptolemaeus (lunar crater) 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 Ptolemaeus (lunar crater)?

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 Ptolemaeus (lunar crater).