astronomy

Messier 107

Messier 107 is a astronomy 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 Messier 107 rather than just read about it. In short: Messier 107 or M107, also known as NGC 6171 or the Crucifix Cluster, is a very loose globular cluster close to the equator in Ophiuchus, and is the last such object in the Messier Catalogue. Observational history, namings and guide It was discovered by Pierre Méchain in April 1782, then independently by William Herschel in 1793.

Key takeaways

Messier 107 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Messier 107 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Messier 107 from memory before moving on to harder problems.

Reference excerpt

Messier 107 or M107, also known as NGC 6171 or the Crucifix Cluster, is a very loose globular cluster close to the equator in Ophiuchus, and is the last such object in the Messier Catalogue.

Observational history, namings and guide It was discovered by Pierre Méchain in April 1782, then independently by William Herschel in 1793. Herschel's son, John, in his 1864 General Catalogue, described it as a "globular cluster of stars, large, very rich, very much compressed, round, well resolved, clearly consisting of stars". It was not until 1947 that Helen Sawyer Hogg added it and three other objects found by Méchain to the modern Catalogue, the latter having contributed several of the suggested observation objects which Messier had verified and added. The cluster is to be found 2.5° south and slightly west of the star Zeta Ophiuchi.

Properties M107 is close to the galactic plane and about 20,900 light-years from Earth and 9,800 ly (3,000 pc) from the Galactic Center. Its orbit is partly as far out as the galactic halo, as is between 9,200–12,400 ly (2,820–3,790 pc) from the Galactic Center, the lower figure, the "perigalactic distance" sees it enter and leave the galactic bar. There are 22 known RR Lyrae variable stars in this cluster and a probable SX Phoenicis variable.

Illustrations

Worked examples

Example 1 — a first encounter with Messier 107

Start with the simplest possible case. Write down what Messier 107 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 Messier 107 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 Messier 107 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 Messier 107

In research: Messier 107 appears in astronomy 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 Messier 107 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: Messier 107 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1782, Discoveries by Pierre Méchain, Globular clusters, so understanding it makes those chapters shorter.
In everyday life: Look for Messier 107 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 Messier 107 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Messier 107 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 Messier 107 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 107 in simple terms?

Messier 107 or M107, also known as NGC 6171 or the Crucifix Cluster, is a very loose globular cluster close to the equator in Ophiuchus, and is the last such object in the Messier Catalogue. Observational history, namings and guide It was discovered by Pierre Méchain in April 1782, then independent…

Why does Messier 107 matter?

Because it connects several astronomy 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 Messier 107?

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 Messier 107.