astronomy

Y. N. Jayarathna

Y. N. Jayarathna 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 Y. N. Jayarathna rather than just read about it. In short: Rear Admiral Y. N.

Key takeaways

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

Reference excerpt

Rear Admiral Y. N. Jayarathna, RWP, RSP, USP is a retired Sri Lankan admiral and hydrographer. He served as the Chief of Staff of the Sri Lanka Navy and Joint chief Hydrographer to the Government of Sri Lanka, former Commandant of the Naval and Maritime Academy and Commanding Officer, 4th Fast Attack Flotilla.

Education Jayarathna was educated at the Royal College Colombo, where he was a senior cadets when the cadet contingent won the Herman Loos Challenge Cup.

Naval career

Early career Having joined the Sri Lanka Navy in 1986 as an Officer Cadet, Jayarathna received his basic training at the Naval and Maritime Academy, where he topped his batch winning the Sword of Honour and was selected for the International Midshipman Course at Britannia Royal Naval College from 1988 to 1989. He was commissioned a Sub Lieutenant in 1988, and was attached to the 4th Fast Attack Flotilla on his return from the United Kingdom, serving in the Dvora class fast patrol boats that became the primary offensive weapon of the navy against the Sea Tigers as the Sri Lankan Civil War escalated. He followed the sub lieutenant technical course in India in 1989. Jayarathna spent most of his career with the 4th Fast Attack Flotilla, going on to serve an additional officer, second in command, officer in command and the training officer. He also specialized in hydrography, having attended the basic hydrography course in 1995 and long hydrography course in 2003 at the National Institute of Hydrography in Goa, gaining a Master's in Hydrography from the University of Goa in 2003. He attended the Army Command and Staff College gaining the psc qualification and a Master's in Defence Studies from the University of Kelaniya in 2001. Jayarathna had served at Naval Headquarters as Senior Staff Officer Projects and Plans; and Senior Staff Officer of Navy Hydrographic Service.

Higher command Jayarathna took command of the 4th Fast Attack Flotilla from 2007 to 2008, during the last stages of the war. At Naval Headquarters, he had served as Deputy Director Naval Project & Plans, Acting Director Maritime Surveillance, Deputy Director Naval Operations and Acting Director Naval Research Wing. From 2009 to 2011, he served as the Defence Advisor to at the Sri Lankan High Commission in New Delhi. In 2011, took command of SLNS Samudura. The following year he was appointed as Naval Assistant to the Commander of the Navy and Head of Naval Research, serving in these positions until he was appointed Commandant of the Naval and Maritime Academy in 2014. Having completed the national defence course at the PLA National Defence University, he served as Deputy Area Commander Northern Naval Area, Deputy Director General Sri Lanka Coast Guard, Deputy Area Commander Eastern Naval Area and Port Facility Security Officers of Trincomalee Port, Director Naval Training, Director General Training and Director General Operations. Jayarathna served concurrently as Joint Chief Hydrographer to the Government of Sri Lanka and Chief Hydrographer of the Navy. He was serving as Commander Eastern Naval Area when in May 2021, he was appointed Deputy Chief of Staff of the Sri Lanka Navy and in August 2021 he was appointed Chief of Staff. He was a member of the Delineation of Outer Continental Margin Project, Advisory group on effect of Sethusamudram Canal Project, Interim Tsunami Warning Committee. He also served as a member in the National Committee on Ocean Science under National Science Foundation of Sri Lanka. After about 36 years of service Rear Admiral YN Jayarathne retired from naval service 21 June 2022.

Decorations Jayarathna has been awarded the gallantry medals Rana Wickrama Padakkama twice and Rana Sura Padakkama; the service medals Uttama Seva Padakkama and Sri Lanka Armed Services Long Service Medal with clasp. His other medals Videsha Seva Padakkama, Sri Lanka Navy 50th Anniversary Medal, 50th Independence Anniversary Commemoration Medal, Eastern Humanitarian Operations Medal with two clasps, Northern Humanitarian Operations Medal, Purna Bhumi Padakkama and North and East Operations Medal. He has gained the fast attack craft (FAC) squadron pin, surface warfare badge and the passed staff college (psc) badge.

Worked examples

Example 1 — a first encounter with Y. N. Jayarathna

Start with the simplest possible case. Write down what Y. N. Jayarathna 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 Y. N. Jayarathna 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 Y. N. Jayarathna 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 Y. N. Jayarathna

In research: Y. N. Jayarathna 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 Y. N. Jayarathna 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: Y. N. Jayarathna is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alumni of Royal College, Colombo, Alumni of the University of Kelaniya, Defence Services Command and Staff College graduates, so understanding it makes those chapters shorter.
In everyday life: Look for Y. N. Jayarathna 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 Y. N. Jayarathna in 20 minutes

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

Frequently asked questions

What is Y. N. Jayarathna in simple terms?

Rear Admiral Y. N.

Why does Y. N. Jayarathna 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 Y. N. Jayarathna?

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 Y. N. Jayarathna.