astronomy

Messier 38

Messier 38 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 38 rather than just read about it. In short: Messier 38 or M38, also known as NGC 1912 or Starfish Cluster, is an open cluster of stars in the constellation of Auriga. It was discovered by Giovanni Batista Hodierna before 1654 and independently found by Guillaume Le Gentil in 1749.

Key takeaways

Messier 38 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 38 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Messier 38 from memory before moving on to harder problems.

Reference excerpt

Messier 38 or M38, also known as NGC 1912 or Starfish Cluster, is an open cluster of stars in the constellation of Auriga. It was discovered by Giovanni Batista Hodierna before 1654 and independently found by Guillaume Le Gentil in 1749. The open clusters M36 and M37, also discovered by Hodierna, are often grouped together with M38. Distance is about 1.066 kpc (3,480 ly) away from Earth. The open cluster NGC 1907 lies nearby on the sky, but the two are most likely just experiencing a fly-by, having originated in different parts of the galaxy.

Description The cluster's brightest stars form a pattern resembling the Greek letter Pi or, according to Webb, an "oblique cross". Walter Scott Houston described its appearance as follows:

Photographs usually show a departure from circularity, a feature quite evident to visual observers. Older reports almost always mention a cross shape, which seems more pronounced with small instruments. A view with a 24-inch reflector on a fine Arizona night showed the cluster as irregular, and the host of stars made fruitless any effort to find a geometrical figure. At its distance of 1066 pc., its angular diameter of about 20 arc minutes corresponds to about 4.0 parsecs (13 light years), similar to that of its more distant neighbor M37. It is of intermediate age at about 290 million years. From the population of about 100 stars, this open cluster features a prominent yellow giant with the apparent magnitude +7.9 and spectral type G0 as its brightest member. This corresponds to an absolute magnitude of -1.5, or a luminosity of 900 Suns. For comparison, the Sun would appear as a faint magnitude +15.3 star from the distance of M38.

Components

Gallery

See also List of Messier objects Messier 36 Messier 37

References

External links

Messier 38, SEDS Messier pages

Messier 38 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images NASA Astronomy Picture of the Day: Open Star Cluster M38 (7 January 2003)

Illustrations

Worked examples

Example 1 — a first encounter with Messier 38

Start with the simplest possible case. Write down what Messier 38 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 38 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 38 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 38

In research: Messier 38 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 38 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 38 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1654, Auriga, Messier objects, so understanding it makes those chapters shorter.
In everyday life: Look for Messier 38 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 38 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Messier 38 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 38 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 38 in simple terms?

Why does Messier 38 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 38?

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 38.