Year Definition and 999 Threads

A year is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked.
A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars; see below. For the Gregorian calendar, the average length of the calendar year (the mean year) across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a (for Latin annus) to represent a year of either 365 or 366 days. In English, the abbreviations y and yr are commonly used.
In astronomy, the Julian year is a unit of time; it is defined as 365.25 days of exactly 86,400 seconds (SI base unit), totalling exactly 31,557,600 seconds in the Julian astronomical year.The word year is also used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. Similarly, year can mean the orbital period of any planet; for example, a Martian year and a Venusian year are examples of the time a planet takes to transit one complete orbit. The term can also be used in reference to any long period or cycle, such as the Great Year.

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  1. matthyaouw

    VOTE PF PHOTO CONTEST - New year, new photo.

    Multiple choice again. Vote for your fave(s) 1.Edward http://img122.imageshack.us/img122/250/1001102jpgchristmasflowde4.jpg 2.LennoxLewis http://img98.imageshack.us/img98/1387/img0016lowresra7.jpg 3.ZapperZ 4.Marzena 5.Borek 6.Matthyaouw 7.Hypatia...
  2. J

    30 Year Treasury/10 Year AAA Bond Spread

    For fun I showed this to my parents. They don't have the guts to play spreads. I have no money to invest so, tell me what you guys think. Why Short Long Bonds If my calculations are correct a drop in the 30 year treasury to 2% from 3.22% would result in 21.3% capital gain on a long...
  3. C

    Vote for "Game of the Year" 2020 | Last Year's Results

    So: I do a "game of the year" poll every year. The poll gives you a list of nearly every game released last year, and asks you to make a list of your favorites (up to your top 20). If you would like to vote in it (and if it's okay for me to link this) you can click here to vote. For...
  4. Borek

    Happy New Year Everyone: Green-Haired One

    Green haired one :smile:
  5. matthyaouw

    PF PHOTO CONTEST - New year, new photo (Dec 27 to Jan 3)

    New year, new photo Last month I barely took my camera out, so for 2009 I'm going to promise myself I'll do better. This week I want everyone to go out and take a NEW photo. No restrictions on subject, it just has to have been taken within the contest period- no recycled pictures please...
  6. A

    Can I Get Accepted and Funded for an MSc in Theoretical Physics in the USA?

    I'm graduating in physics this year at a not-very-well-known-but-still-good-college and I was hoping to try an MSc in theoretical physics somewhere out there -> America (Caltech, Berkeley, bla bla bla bla)! My grades are not asian standard excellent (I have about 70-80% average), and it would...
  7. M

    Physics Year 12, Need Some Advice

    Hey Guys, Well, I've decided to do Physics In year 12, but i haven't done it in year 11. Now I've always been interested in physics a whole deal and i did particulary well in Introductory Calculus in year 11, what i was wondering is in preparation for year 12 physics, do you guys/girls have...
  8. G

    Discover the Fundamentals of 1st Year Physics | Undergraduate Curriculum

    What is taught to a 1st year physics undergraduate?
  9. S

    Question about 5 year M.S. in physics

    Hi I found this forum about a week ago and really enjoy it. but anyway I would like to go to the University of Colorado and they offer a 5 year master program (in physics), if I wanted to get my PhD from say m.i.t. or the like, is the 5 year plan a viable option or would i be better of just...
  10. F

    Schools Do first year undergrad marks matter when applying to grad school?

    Hey all! Just made a PF account and have this question on my mind... So I'm going into my 2A semester in January (because I'm in co-op and so I don't have the traditional schedule), and I completely messed up my first year at University. The reason was because I had to take 3 non-math...
  11. JasonJo

    Programs Harder to get into PhD program this year?

    Will it be tougher to get into a PhD program this year due to the economic situation? I know at my school there have been budget cuts and I'm sure many other public univerisities are doing the same. I've also heard that a few private institutions have taken sizable hits to their endowment...
  12. Topher925

    Why Do Some People Enjoy Holiday Shopping Despite the Stress?

    One thing I dislike most about christmas is the shopping and materialism. I'm poor, and never know what to get family members, which seem to change every 3 years. This usually leads to large amounts of stress this time of year and me wasting countless hours online looking for deals when I should...
  13. A

    Teaching Arithmetic Through Physical Manipulation: A Creative Approach

    i want to teach my boy arithmetic. my current 'best' idea, is to have a board with a few columns with nine spaces in each column. headings from right to left would be (units,tens, hundreds etc.). nine small plastic discs showing value of +1 unit. nine discs showing value +10 units. nine...
  14. I

    Can All Solids Be Liquefied by Increasing Pressure?

    Homework Statement Which of the following solid substances can be liquefied simply by increasing the pressure suffciently? ice (H2O) diamond (C) dry ice (CO2) sulfur (S) graphite (C) Which of the following substances cannot be liquified at 1 atm pressure? nitrogen (N2) helium (He)...
  15. G

    Detention For 16 Year Old Who Assaulted 8 Women In Less Than Two Hours

    What kind of penalty would someone like this get here in the US? http://news.bbc.co.uk/1/hi/scotland/glasgow_and_west/7739533.stm
  16. E

    Schools Is a Change in Research Interests and Programs Common in Graduate School?

    Is it normal to be bored of my research at the second year stage of a physics PhD? Or is this a sign that I should be looking elsewhere? I currently find my work (in theoretical physics) too much removed from real-world applications, and I have been thinking of making a switch to electrical...
  17. C

    Nuclear reaction/binding energy problem? Year 11 physics, so its fairly simple.

    Homework Statement In the near future nuclear fusion reactions such as the one shown below may be used to produce electrical power. 2 4 2 H ----> He + energy 1 2 Physicists have suggested that 50 MW of energy will be...
  18. Y

    Calc Midterm, First Year University (derivative related stuff)

    Homework Statement If f(x)=x^x for x>0, find the constant a such that f'(a)=2f(a) Homework Equations The Attempt at a Solution f'(a)=a*a^(a-1) =a^a 2f(a)=2a^a 2a^a=a^a ln2a^a=lna^a aln2a=alna ...?
  19. C

    Year 11 motion/vector problem?

    Homework Statement I'm really not good at motion. It just doesn't seem to come easily to me, which is kind of disapointing, because physics is my favourite subject. Question: A body of mass 5kg is moving in a north easterly direction with a velocity of 28.3 m/s. If a westerly wind acts on...
  20. E

    Repeating a year: What should I do?

    Firstly, some background: I was going to clear my A level papers in a few days' time, but I ended up in ICU after a major operation (sepsis secondary to perforated stomach ulcer) past the duration for which I could take my papers in the hospital. As a result, I'll have to repeat my senior year...
  21. P

    Man shoots at cellphone thief, kills 4 year old.

    In light of the thread Boy, 8 shoots himself at Mass. gun show I thought I'd post this article and throw in my five cents' worth: http://www.newstoday.co.za/cgi-bin/newstoday/show.pl?1225269907 Before I say anything else I just wish to point out that I'm aware that this topic is probably...
  22. S

    You know you're in your first year grad school when

    These are a part of your daily life. (couldn't find the best forum to post this in, but wanted to share it)
  23. J

    Calculating the Year Length of Planet Y Around Alpha

    Planet X orbits the star Alpha with a 'year' that is 200 Earth days long. Planet Y circles Alpha at nine times the distance of planet X. How long is a year on planet Y? I know that I have to use the kepler's law : T^2 = (4pi^2/GM)r^3 but I'm not too sure how to do solve this... Please...
  24. T

    Solving Bibtex Referencing Problem for Multiple Papers in Same Year

    I am having a problem with bibtex when I have a second paper by the same author (or at least the same lead author) in a single year. For example if I have two papers, with the following authors: Paper 1 - Author 1, Author 2, Author 3, Author 4 (2008) Paper 2 - Author 1, Author 5, Author...
  25. Q

    Take a year off to study for PGRE?

    Let's say, hypothetically speaking, that a reasonably good student (GPA > 3.7 in math, physics, a couple publications and research experience in both solid state and theory) expects (from '96, '01 practice test scores) to do quite terribly on the physics GRE (like ~600), but wants to go to a...
  26. A

    Why Do We See the Same Stars All Year?

    My teacher told us today that we can see the same stars in the sky all year long, but when I asked her why she couldn't answer me. She just said, "that's the way God wants it." I would love a scientific explanation please. Thanks, Alexa
  27. D

    To postgrads-lecturers. Getting over 60% in tests in Final year advice needed.

    Hi I need an average this year of over 62%. I am in 4th year physiology and just lecture notes are not enough to achieve grades this high. What I am looking for are good tips that set a minority of students above the rest when marking exams. An example of a Question "Endothelial cells...
  28. F

    Second year university biochemistry - pH and Buffers

    Homework Statement This question is for a lab write up. We prepared a 0.1 M citrate buffer with pH 4.0, we then diluted our buffer with deionized water 20 fold and then 50 fold. The subsequent changes in pH are as follows, 20 fold pH = 4.10 50 fold pH = 4.14 This confuses me because I have...
  29. D

    Limit question first year calc

    It's supposed to be an easy question, but I'm not a math major. Evaluate lim x-->0+ (√(9 + 17lnx + 9ln^2x) - 3√(1 + lnx + ln^2x)) , if the limit exists
  30. A

    1st year Chemistry Course in University

    Hi everyone, I was wondering if anyone would be willing to lend a helping hand to a first year chem student. I have forgotten a lot of material from my high school courses and am currently struggling just with completing the reviews. The book that I'm using is called "General...
  31. T

    How Can First-Year Engineering Students Prepare?

    I'm a first year mechanical engineering student at the university of Witwatersrand( known as wits university). I would like to know what I can do to ensure that I know a lot about what i am getting into. thank you:smile:
  32. V

    What are some unique ideas for a physics final year project?

    I'm just going to my second year in the university as a physics major and I'm trying to beat time by starting research on my final year project(something new and involves both theoretical and experimental ideas) but i don't seem to get any ideas.please help.
  33. B

    Courses Second year, First Semester Courses

    So I just started my first semester in second year and most of my courses seem really interesting and I love what I am studying. My major is a specialist in Biotechnology at UofT(mississauga), and I am currently taking 5 courses: Intro Cell and Molec Bio Intro Physiology (with lab) Fundamentals...
  34. P

    What resources can help me succeed in honors calculus?

    Hey everyone, This is my third day at university. I'm taking an Analysis course and I'm getting owned! I came from a relatively small high school in a small town and we hardly did any proofs at all except for proving trig identities. Now this course is all proofs; I thought I can handle...
  35. F

    How Do Value-Added Services Impact the Telecommunication Industry?

    AOA i am in final year and i want to do my final year project on value-added telecommunication services.but i do not have much information about it. please guide me about this.
  36. wolram

    1. What year did 200 priests die in Chester.

    1. What year did 200 priests die in Chester. 2. Where can a Roman emperor be found with 90km diameter. 3. Who was the philosopher who tried to cure his sight with cow manure and baking in the sun.
  37. ?

    Questions about an Honours Year in Maths

    I'm considering taking honours next year in statistics with a project in financial mathematics. I'm really looking forward to taking more classes in this area, but I have a couple of worries I'd like to air... 1. How smart do you really have to be? I think I'm above the curve, I can get high...
  38. P

    Schools What Can I Expect for Different Years of Graduate School as a Pure Math Major?

    I'm just wondering im going into 2nd year. ..I'm taking Analysis I, Differential Equations Calc III ,Probability all in the same semester and then Abstract Alg I , Linear Alg II , calc IV in 2nd semester Just wondering what I can expect for the differnet years...how much more intense it is
  39. E

    Exploring Quantum Time: A 15 Year Old's Perspective

    Hello. I'm a 15 year old student interested in theoretical physics. I took Calculus I in 7th grade at Hood College, Calculus II in eighth grade, and Calculus III in ninth, so math doesn't scare me. I've heard ideas that the new LHC might confirm a Higgs field, generate micro-black holes...
  40. C

    Narrowing Hubble's Constant - 8 year study concludes

    This is a nice little article on the history of the Hubble Constant and its refinement over time. There is also a summary of the 8 year Cepheid Variable study headed by Wendy Freedman of the Carnegie Observatory in it, in which they try to narrow down the limits of the Hubble Constant via 100s...
  41. H

    Physics Career Guidance - Where Should A Seventeen Year Old Hopeful Astrophysicist Be

    I am overwhelmed by this super competitive science world - where fifteen years olds are entering university worthy research into science competitions, and students are encountering calculus in middle school. I go to a Performing Arts School in NYC which is the farthest place for one who is...
  42. K

    Design Inverter for Solar Cells | Final Year EE Student

    Hi I'm a final year EE student and its time for me to do my project.I've thought of a topic nd thats- "Inverter design for solar cells" but i don know wher to start nd how to proceed. can any of u provide me circuit diagrams with explanations, or any links to such sites.since this is a general...
  43. Cyrus

    Weighing the Cost of Fixing Your 10 Year Old Car

    At what point do you say spending x amount of money on fixing your car isn't worth it anymore? My 10 year old accord needs the front axle fixed, $300. And my radio is busted, so I bought a new head unit w/all wires for around $90.00. I couldn't take not having a radio anymore :rolleyes...
  44. J

    Programs Physics with a year in industry, then a phd?

    Hi, I'm about to start the third year of my degree which is a "year in industry" where I'll be working in an industrial research lab. I'll also be taking exams as part of my program but only "core" parts. Since I'm interested in perhaps doing a phd after I graduate I was wondering if...
  45. P

    Mystery of the "Cosmic Blank Spot": A Billion Light Year Void

    Recently, a rather large nothing was discovered in the Universe (last August by the University of Minnesota team). This cosmic blank spot has no stray stars, no black holes, not even dark matter, and is a billion light years across. Is there a possibility that this could be the result of a...
  46. JasonJo

    How Can I Get Into a PhD Program Right Now?

    Hey guys, I'm wondering how once would go about paying for a fifth year if you already graduated. I could apply to be a nonmatriculated student, but you are not eligible for financial aid. I plan on coming back next semester and doing 3 independent studies (but I won't be signing up for them...
  47. A

    What to do during year off between grad and undergrad?

    I will be graduating with a degree in Math in one year, and I plan on pursuing a PhD. I want graduate schools to consider my final two semesters when looking at my application, so I've decided to take a year off. (I'd apply for a spring semester, but most of the top schools don't allow this.)...
  48. jim mcnamara

    Exploring Epochs & Correction Factors for Tropical Year

    Using this: http://scienceworld.wolfram.com/astronomy/TropicalYear.html I derived this unix C code, which duplicates expected outputs. Note the constant T which is a correction factor for the epoch based in 2000, or so I assume because 2451545 is Jan 1 2000. And I have about epochs in...
  49. P

    Schools Can AP exams substitute a year of university?

    Hello. Well, it looks like I'm going to have to go back for another year of high school due to low marks. However, it is very boring and I regret not doing better because I know everything and far beyond all of the math, science, and english curricula. There were also some complications relating...
  50. R

    YEAR 12 Astrophysics EEI HELP Please?

    YEAR 12 Astrophysics EEI HELP! Please? Homework Statement Hello :) I'm a year 12 student working on my EEI (Extended Experimental Investigation) which is about astrophysics. We are allowed to pick any topic, however we were given some ideas: Sunspots History of Measurement...
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