astronomy

Kushyar ibn Labban

Kushyar ibn Labban 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 Kushyar ibn Labban rather than just read about it. In short: Abu l-Hasan Kūshyār ibn Labbān ibn Bashahrī al-Jīlī (Arabic: أبو الحسن كوشياربن لبّان بن باشهري الجيلي) (971–1029), also known as Kushyar ibn Labban, was an Iranian mathematician, geographer, and astronomer from Gilan, south of the Caspian Sea, Iran. Author of Principles of Hindu Reckoning.

Key takeaways

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

Reference excerpt

Abu l-Hasan Kūshyār ibn Labbān ibn Bashahrī al-Jīlī (Arabic: أبو الحسن كوشياربن لبّان بن باشهري الجيلي) (971–1029), also known as Kushyar ibn Labban, was an Iranian mathematician, geographer, and astronomer from Gilan, south of the Caspian Sea, Iran. Author of Principles of Hindu Reckoning.

Career Kūshyār ibn Labban's main work was probably done about the beginning of the 11th century, and seems to have taken an important part in the elaboration of trigonometry. He continued the investigations of the 10th century mathematician and astronomer Abul Wáfa, and devoted much space to this in his zīj (book of astronomical tables) az-Zīj al-Jamī wal-Baligh ("The Comprehensive and Mature Tables"), which incorporated the improved values of the planetary apogees observed by al-Battani. The tables were translated into the Persian language before the end of the century. He wrote also an astrological introduction and an arithmetic treatise Principles of Hindu Reckoning (Kitab fi usul hisab al-hind), that is extant in both Arabic and Hebrew), and was translated to English in 1963. Kūshyār Daylami's pupils included the Persian mathematician Ali ibn Ahmad al-Nasawi. Kūshyār ibn Labban is thought to have died in Baghdad.

Works All of Kushyar’s surviving works were composed in Arabic. The popularity of his astrological handbook is evident from its transmission in Persian, Turkish, and Chinese manuscripts.

Kitāb fī Uṣūl ḥisāb al-Hind (Book on the Principles of Hindu Reckoning). Kitāb al-Asṭurlāb (Book on the Astrolabe). al-Madkhal fī ṣināʿat aḥkām al-nujūm, also: Mujmal al-uṣūl fī aḥkām al-nujūm (Introduction to the Art of Astrology / Summary of the Principles of Astrology). al-Zīj al-Jāmiʿ (The Comprehensive Astronomical Tables/Zīj). al-Zīj al-Bāligh (The Extensive/Mature Astronomical Tables) of which only one chapter survives.

References

Further reading O'Connor, J.J.; Robertson, E.F. (2003). "Kushyar ibn Labban". MacTutor. University of St Andrews. Retrieved 7 March 2023. Suter, Heinrich (1900). Die Mathematiker und Astronomen der Araber und ihre Werke (in German). Leipzig: Teubner. OCLC 230703086. Bagheri, Mohammad (2007). "Ibn Labbān, Kūshyār: Kiyā Abū al‐Ḥasan Kūshyār ibn Labbān Bāshahrī al‐Jīlī (Gīlānī)". In Thomas Hockey; et al. (eds.). The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 560–1. ISBN 978-0-387-31022-0. (PDF version)

Worked examples

Example 1 — a first encounter with Kushyar ibn Labban

Start with the simplest possible case. Write down what Kushyar ibn Labban 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 Kushyar ibn Labban 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 Kushyar ibn Labban 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 Kushyar ibn Labban

In research: Kushyar ibn Labban 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 Kushyar ibn Labban 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: Kushyar ibn Labban is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1029 deaths, 10th-century Iranian astronomers, 10th-century Iranian mathematicians, so understanding it makes those chapters shorter.
In everyday life: Look for Kushyar ibn Labban 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 Kushyar ibn Labban in 20 minutes

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

Frequently asked questions

What is Kushyar ibn Labban in simple terms?

Why does Kushyar ibn Labban 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 Kushyar ibn Labban?

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 Kushyar ibn Labban.