astronomy

Messier 70

Messier 70 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 70 rather than just read about it. In short: Messier 70 or M70, also known as NGC 6681, is a globular cluster of stars to be found in the south of Sagittarius. It was discovered by Charles Messier in 1780.

Key takeaways

Messier 70 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 70 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Messier 70 from memory before moving on to harder problems.

Reference excerpt

Messier 70 or M70, also known as NGC 6681, is a globular cluster of stars to be found in the south of Sagittarius. It was discovered by Charles Messier in 1780. The famous comet Hale–Bopp was discovered near this cluster in 1995. It is about 29,400 light years away from Earth and around 6,500 light-years from the Galactic Center. It is roughly the same size and luminosity as its neighbour in space, M69. M70 has a very small core radius of 0.22 ly (0.068 pc) and a half-light radius of 182.0 ly (55.80 pc). This cluster has undergone core collapse, leaving it centrally concentrated with the luminosity distribution following a power law. There are two distinct stellar populations in the cluster, with each displaying unique abundances. These likely represent different generations of stars. Five known variable stars lie within its broadest radius, the tidal radius, all of which are RR Lyrae variables. The cluster may have two blue stragglers near the core.

Gallery

Illustrations

Worked examples

Example 1 — a first encounter with Messier 70

Start with the simplest possible case. Write down what Messier 70 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 70 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 70 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 70

In research: Messier 70 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 70 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 70 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1780, Discoveries by Charles Messier, Globular clusters, so understanding it makes those chapters shorter.
In everyday life: Look for Messier 70 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 70 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Messier 70 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 70 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 70 in simple terms?

Messier 70 or M70, also known as NGC 6681, is a globular cluster of stars to be found in the south of Sagittarius. It was discovered by Charles Messier in 1780.

Why does Messier 70 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 70?

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 70.