I knew that tbelow were $365.25$ days in a year (ish) however we just have $365$ on calendars, that"s why we have February 29. I then learned in class about the sideactual and also solar day; sidegenuine being $23$ hrs and also $56$ minutes, and also solar being $24$.

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When we say "$365.25$ days" which day are we talking about (sidereal or solar)?

My teacher shelp that the $4$ minutes we acquire from the solar day being longer than the sidegenuine day resulted in the $0.25$ (ish) more, which reasons February 29. I do not see how being $4$ minutes ahead each day already suggests that we must add also even more time. Sucount the $4$ minutes each day, that adds approximately $24.3$ hours added each year, suggests that we must remove a day eexceptionally single year, not add one.

What does being $4$ minutes ahead/behind mean for the year?


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edited Mar 21 "17 at 11:29
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Qmechanic♦
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asked Mar 20 "17 at 18:10
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JayembyJayemby
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Tbelow seems to be some confusion. The number of solar days in a year differs from the number of sidegenuine days in year by 1--that difference of course being due the 1 rdevelopment about the sun per year influencing the solar day.

Back to the variety of days in a year: Baring tidal resonances, tbelow is no reason for the size of a day to be commensurate via length of year; it is what is it: 365.2425

I remember this as follows:

365 day in the year

+1/4 A leap year eextremely 4 years

-1/100 Except on years finishing in "00"

+1/400 Unless the year is divisible by 400 (e.g. Y2K)

365.2425

so that 2000 was a leap-leap-leap year.


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answered Mar 20 "17 at 19:32
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JEBJEB
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4 minutes a day accumulates to 24.3 hrs in a year - ie the moment it takes for the earth to revolve as soon as, even more or much less. This in significance is why the distinction between the sideactual day and also the solar day is 4 minutes.

It has nothing to perform through leap years. These aclimb bereason the earth"s orbital period is 365.2422 days. So we have include a day to the year every 4 years, so that things don"t go adrift also a lot - but that over-corrects, so eexceptionally century, the leap year is omitted. But then this goes a bit too far the other means, so actually eextremely 400 years (eg 1600, 2000) the century year does have a leap year. This gets pretty cshed to 365.2422.


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edited Mar 20 "17 at 20:19
answered Mar 20 "17 at 19:03
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Dr ChuckDr Chuck
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Very roughly: we consist of the four minutes through our passage approximately the sun.

23hrs 56mins rotation of the Earth keeps the stars in the very same location each sidegenuine day; 24hrs rotation of the Planet keeps the Sun in the very same place in the sky each solar day. We"re relocating about the Sun over the course of the year, so we need to include a few even more minutes to account for that.

The 4 minutes are pertinent for things like satellites, which just care about rotation approximately and of the world, however for calendar use they are not crucial as our calendar is based upon where the sun is in the skies.

All this indicates that you can safely disregard the sidereal day for the majority of purposes; as such, the four minute difference has actually nothing to carry out via leap seconds and such, which are all defined in regards to solar days.

When we say "365.25 days" which day are we talking around (sidereal or solar)?

Solar days!

This is basically "random"; there is no (substantial) connect between the length of a day and also the length of a year; we"re spinning as we go about the sun, and also it would be quite the co-incidence if we occurred to be back to precisely where we began in spin at the exact same time we"re earlier wbelow we began in orlittle bit.

(This actually have the right to and also does happen as an outcome of orbital resonances, the many famous example being the moon which is nearly entirely tidally locked. But hey.)

The added quarter of a day is simply dvery own to that, nopoint to execute with the sidegenuine counter.

My teacher sassist that the 44 minutes we get from the solar day being much longer than the sidereal day resulted in the 0.25 (ish) even more, which causes February 29.

Your teacher is wrong.

This is obvious actually, given that 44 minutes is nowhere near quarter of a day.

Less waffly summary from Wikipedia article on Sidereal Time:

Sidereal time is a time-keeping mechanism. It is offered by astronomers to discover celestial objects. Using sideactual time it is feasible to point a telescope to the proper collaborates in the night sky.

Sideactual time is a "time scale based upon Earth"s price of rotation measured loved one to the resolved stars".

Because the Planet moves in its orlittle bit about the Sun, a intend solar day is around 4 minutes longer than a sidegenuine day. Hence, a star shows up to rise four minutes earlier each night, compared to solar time. Different stars are visible at various times of the year.

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By comparison, solar time is reckoned by the motion of the Earth from the perspective of the Sun. An average solar day (24 hours) is longer than a sideactual day (23 hours, 56 minutes, 4 seconds) because of the amount the Planet moves each day in its orbit around the Sun.

There are additionally some excellent existing answers on Stack Exadjust that say the same thing in different means (so, if you review them all, you"ll have gained it!); for example:

And, lastly, a valuable illustration:

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