astronomy

IC 438

IC 438 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 IC 438 rather than just read about it. In short: IC 438 is a spiral galaxy in the constellation of Lepus. Its velocity with respect to the cosmic microwave background is 3,199±6 km/s, which corresponds to a Hubble distance of 153.9 ± 10.8 Mly (47.18 ± 3.30 Mpc).

Key takeaways

IC 438 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IC 438 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IC 438 from memory before moving on to harder problems.

Reference excerpt

IC 438 is a spiral galaxy in the constellation of Lepus. Its velocity with respect to the cosmic microwave background is 3,199±6 km/s, which corresponds to a Hubble distance of 153.9 ± 10.8 Mly (47.18 ± 3.30 Mpc). However, 17 non-redshift measurements give a much closer distance of 136.45 ± 4.29 Mly (41.835 ± 1.314 Mpc). It was discovered by American astronomer Lewis Swift on 7 January 1891. IC 438 is a Seyfert I Galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.

IC 438 Group According to A.M. Garcia, IC 438 is one of five members of the IC 438 galaxy group (also known as LGG 134), which includes IC 2143, UGCA 113, MCG-03-15-021, and ESO 555-5.

Supernovae Three supernovae have been observed in IC 438:

SN 1997B (Type Ic, mag. 16.5) was discovered by Alessandro Gabrijelcic on 13 January 1997. SN 2016blx (Type II, mag. 16.5) was discovered by the Backyard Observatory Supernova Search (BOSS) on 9 April 2016. SN 2017gbb (Type Iax[02cx-like], mag. 16.39) was discovered by the Gaia Photometric Science Alerts programme on 9 August 2017.

Image gallery

Illustrations

Worked examples

Example 1 — a first encounter with IC 438

Start with the simplest possible case. Write down what IC 438 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 IC 438 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 IC 438 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 IC 438

In research: IC 438 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 IC 438 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: IC 438 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1891, Discoveries by Lewis Swift, ESO objects, so understanding it makes those chapters shorter.
In everyday life: Look for IC 438 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 IC 438 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what IC 438 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 IC 438 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is IC 438 in simple terms?

Why does IC 438 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 IC 438?

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 IC 438.