<p>It's not exactly one year because of the 28/29 February thing. </p>

<p>The exact period is 365 days 6 hours 9 minutes 9 seconds [Random House Encyclopedia. New York: Random House: 174.]</p>

CC BY-SA 3.0
2018-01-01T16:55:26.303Z
A year in which we assign an extra day is called a leap year. Every now and then we also add leap seconds.
George
CC BY-SA 3.0
2018-01-01T15:06:25.193Z
2018-01-01T15:06:25.193Z
user174411
<p>A <a href="https://en.wikipedia.org/wiki/Year#Sidereal,_tropical,_and_anomalistic_years" rel="nofollow noreferrer">sidereal year</a> is 365.256363004 days (365 d 6 h 9 min 9.76 s).</p>

<p>One of the well known Web <a href="https://www.timeanddate.com/calendar/" rel="nofollow noreferrer">calendars</a> and <a href="https://www.timeanddate.com/date/dateadd.html" rel="nofollow noreferrer">date calculators</a> is at: <a href="https://www.timeanddate.com/" rel="nofollow noreferrer">https://www.timeanddate.com/</a>.</p>

<p>Here is the result for your specific question 1/1/2017+1year = <a href="https://www.timeanddate.com/date/dateadded.html?m1=1&amp;d1=1&amp;y1=2017&amp;type=add&amp;ay=1&amp;am=&amp;aw=&amp;ad=&amp;h1=00&amp;i1=00&amp;s1=00&amp;ah=&amp;ai=&amp;as=&amp;rec=" rel="nofollow noreferrer">1/1/2018</a>. Adding exactly one year (on a calendar) gives you one year later, everything is the same except the 'year number'.</p>

CC BY-SA 3.0
2018-01-02T19:18:10.257Z
2018-01-02T19:18:10.257Z
Rob
<p>If we take midnight of 1/1/2017 in any country and mark in space where the center of the Earth is located, at what date, in the same country, has the center completed a full orbit.</p>

<p>I am almost certain that has to be 1/1/2018, but I am not so sure about the hour. </p>

CC BY-SA 3.0
2018-01-01T21:18:53.600Z
There was a study in Nature magazine that said the inner core rotates in the same direction as the Earth and slightly faster, completing its once-a-day rotation about two-thirds of a second faster than the entire Earth. Every year it does 365 rotations about 4 seconds faster than a mark on a country... You said orbit, which implies heliocentric rather than a rotation, so the country marker shifts and arrives at a full sun orbit after the core does. I don't think you mean orbit though!
bandybabboon
CC BY-SA 3.0
2018-01-02T01:51:41.453Z
While not precisely accurate, because the entire orbit moves, but quite slowly, you can look up the precise Perihelion and aphelion dates and times or the precise solstice dates and times to give you an approximation of 1 complete orbit.   None of those occur on January 1st, and they're not exact, they'll be pretty close to one orbit start to finish.
userLTK
<earth><planetary-transits>
How long does it take the center of the Earth to complete a full orbit?
kafkarudo
# How long does it take the center of the Earth to complete a full orbit?

(Asked by: username_0 on 2017-12-31)

If we take midnight of 1/1/2017 in any country and mark in space where the center of the Earth is located, at what date, in the same country, has the center completed a full orbit.

I am almost certain that has to be 1/1/2018, but I am not so sure about the hour.

**Tags:** earth, planetary-transits

> **Comments:**
> **username_1**: There was a study in Nature magazine that said the inner core rotates in the same direction as the Earth and slightly faster, completing its once-a-day rotation about two-thirds of a second faster than the entire Earth. Every year it does 365 rotations about 4 seconds faster than a mark on a country... You said orbit, which implies heliocentric rather than a rotation, so the country marker shifts and arrives at a full sun orbit after the core does. I don't think you mean orbit though!  
> **username_2**: While not precisely accurate, because the entire orbit moves, but quite slowly, you can look up the precise Perihelion and aphelion dates and times or the precise solstice dates and times to give you an approximation of 1 complete orbit.   None of those occur on January 1st, and they're not exact, they'll be pretty close to one orbit start to finish.  

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## 2 answers

### Answer by username_3 on 2018-01-01. Score: 3

It's not exactly one year because of the 28/29 February thing.

The exact period is 365 days 6 hours 9 minutes 9 seconds [Random House Encyclopedia. New York: Random House: 174.]

> **Comments:**
> **username_4**: A year in which we assign an extra day is called a leap year. Every now and then we also add leap seconds.  

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### Answer by username_5 on 2018-01-02. Score: 2

A [sidereal year](https://en.wikipedia.org/wiki/Year#Sidereal,_tropical,_and_anomalistic_years) is 365.256363004 days (365 d 6 h 9 min 9.76 s).

One of the well known Web [calendars](https://www.timeanddate.com/calendar/) and [date calculators](https://www.timeanddate.com/date/dateadd.html) is at: <https://www.timeanddate.com/>.

Here is the result for your specific question 1/1/2017+1year = [1/1/2018](https://www.timeanddate.com/date/dateadded.html?m1=1&d1=1&y1=2017&type=add&ay=1&am=&aw=&ad=&h1=00&i1=00&s1=00&ah=&ai=&as=&rec=). Adding exactly one year (on a calendar) gives you one year later, everything is the same except the 'year number'.


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