astronomy

Samer Hattar

Samer Hattar 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 Samer Hattar rather than just read about it. In short: Samer Hattar (Arabic: سامر حتر) is a chronobiologist and a leader in the field of non-image forming photoreception. He is the Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health, part of the National Institutes of Health.

Key takeaways

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

Reference excerpt

Samer Hattar (Arabic: سامر حتر) is a chronobiologist and a leader in the field of non-image forming photoreception. He is the Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health, part of the National Institutes of Health. He was previously an associate professor in the Department of Neuroscience and the Department of Biology at Johns Hopkins University in Baltimore, MD. He is best known for his investigation into the role of melanopsin and intrinsically photosensitive retinal ganglion cells (ipRGC) in the entrainment of circadian rhythms.

Life Samer Hattar was born in Amman, Jordan to a Jordanian father and a Lebanese mother. Raised in a Christian family, he planned on becoming a priest. He studied at Terra Sancta High School, a Catholic high school in Amman, from 1978 to 1988. He earned good grades in his classes and fell in love with biology when introduced to Mendel's pea plant experiments. This passion inspired him to pursue a career in science. He attended Yarmouk University in Irbid for his undergraduate studies, where he majored in Biology and minored in Chemistry. His high marks earned him the honor of meeting Hassan Bin Talal, the prince of Jordan. After graduating from Yarmouk in 1991, he completed a master's degree in biochemistry at the American University of Beirut in Beirut. He began his graduate studies in biochemistry in 1993 at the University of Houston where he studied circadian regulation of a transcription factor in aplysia. Hattar completed his postdoctoral fellowship at the Solomon Snyder Department of Neuroscience at Johns Hopkins University School of Medicine, where he made discoveries on ipRGCs. In 2004, he established his laboratory in the Department of Biology at Johns Hopkins University. He is married to Rejji Kuruvilla, a neuroscientist also working at Johns Hopkins.

Scientific work

Hattar is known for his work in the area of chronobiology. He is credited with discovering that the photopigment melanopsin and associated ipRGCs play an important role in the entrainment of circadian rhythms Before Hattar's work, it was assumed that organisms entrained to daily light-dark cycles through the same mechanisms that are responsible for vision. However, case studies reported that some who were completely blind could still entrain to these cycles. This observation, coupled with the discovery of melanopsin by Ignacio Provencio, led Hattar to hypothesize that this photopigment might be responsible for photoentrainment.

Awards and honors Albert Lehninger Research Award, 2004 Alfred P. Sloan Research Fellow, 2006 Lucile & David Packard Foundation Fellowship for Science and Engineering, 2006

References

External links JHU Biology Department: Dr. Hattar's page

Worked examples

Example 1 — a first encounter with Samer Hattar

Start with the simplest possible case. Write down what Samer Hattar 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 Samer Hattar 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 Samer Hattar 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 Samer Hattar

In research: Samer Hattar 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 Samer Hattar 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: Samer Hattar is common in secondary-school and first-year university syllabi. It links to neighbouring topics American University of Beirut alumni, Chronobiologists, Johns Hopkins University faculty, so understanding it makes those chapters shorter.
In everyday life: Look for Samer Hattar 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 Samer Hattar in 20 minutes

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

Frequently asked questions

What is Samer Hattar in simple terms?

Why does Samer Hattar 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 Samer Hattar?

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 Samer Hattar.