astronomy

Southern Comet of 1947

Southern Comet of 1947 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 Southern Comet of 1947 rather than just read about it. In short: The Southern Comet of 1947 (also known with the designations C/1947 X1, 1947 XII, and 1947n) was a bright comet that became visible in the Southern Hemisphere in December 1947. At that point, it was the brightest comet seen in two decades and is one of the brightest comets seen since 1935, with an estimated maximum apparent magnitude of −3.

Key takeaways

Southern Comet of 1947 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Southern Comet of 1947 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Southern Comet of 1947 from memory before moving on to harder problems.

Reference excerpt

The Southern Comet of 1947 (also known with the designations C/1947 X1, 1947 XII, and 1947n) was a bright comet that became visible in the Southern Hemisphere in December 1947. At that point, it was the brightest comet seen in two decades and is one of the brightest comets seen since 1935, with an estimated maximum apparent magnitude of −3.

Observational history The comet passed from its perihelion on 2 December 1947, at a distance of 0.11 AU from the Sun, while closest approach to Earth was on 7 December, at a distance of 0.85 AU. The approach geometry was such that the comet could have been too faint to be discovered as it approached the Sun. After the first days of October, the comet approached rapidly the Sun and despite getting brighter, it was difficult to observe. On perihelion date, it is estimated that the comet was located 6 degrees at the Sun in the morning sky. Then it moved again in conjunction with the Sun and entered the evening sky. The comet was discovered in evening twilight by many different observers on 8 December 1947, however there were unconfirmed reports from Cape Colony that it was spotted on 7 December. There is a report from Horsham, Australia, that the comet was seen in daylight about an hour before sunset. Harold Pallot, who taught astronomy in the local school, estimated the magnitude of the comet to be at least −5. The tail of the comet upon discovery was estimated by John Paraskevopoulos to be at least 25 degrees in length. The next day Paraskevopoulos estimated the magnitude of the comet to be +1. Jorge Bobone, from the National Astronomical Observatory in Cordoba, Argentina, observed the comet telescopically on 10 December and noted that it had two nuclei 6.3 arcseconds apart. Zdenek Sekanina estimated that the nuclei were separated on 30 November 1947. On 11 December the comet reached its southernmost declination, at −35°. By mid December, the comet was estimated to have a magnitude of 4 to 5, while Paraskevopoulos estimated it to be 2.5–3. The tail was estimated to be 1.5 degrees long, it was made of three components and appeared ragged. The two nuclei were about 10 arcseconds apart, as observed by Willem Hendrik van den Bos. The comet continued to fade rapidly and was last seen by naked eye on 25 December, while by the end of the month its magnitude was estimated to be around 8. The nuclei were still observable, being about 17 arcseconds apart in a plate obtained on 31 December. The comet was last detected on 20 January 1948 by George Van Biesbroeck.

Notes

References

External links C/1947 X1-A at the JPL Small-Body Database C/1947 X1-B at the JPL Small-Body Database Image of the comet from the Montevideo Observatory

Illustrations

Worked examples

Example 1 — a first encounter with Southern Comet of 1947

Start with the simplest possible case. Write down what Southern Comet of 1947 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 Southern Comet of 1947 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 Southern Comet of 1947 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 Southern Comet of 1947

In research: Southern Comet of 1947 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 Southern Comet of 1947 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: Southern Comet of 1947 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1947, Near-Earth comets, Non-periodic comets, so understanding it makes those chapters shorter.
In everyday life: Look for Southern Comet of 1947 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 Southern Comet of 1947 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Southern Comet of 1947 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 Southern Comet of 1947 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Southern Comet of 1947 in simple terms?

Why does Southern Comet of 1947 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 Southern Comet of 1947?

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 Southern Comet of 1947.