i knew the there were \$365.25\$ job in a year (ish) yet we only have \$365\$ on calendars, that"s why we have actually February 29. Ns then learned in class about the sidereal and solar day; sidereal being \$23\$ hours and also \$56\$ minutes, and also solar being \$24\$.

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

My teacher said that the \$4\$ minutes we gain from the solar job being much longer than the sidereal day resulted in the \$0.25\$ (ish) more, which causes February 29. I execute not see how being \$4\$ minute ahead every day already means that we need to include even much more time. Surely the \$4\$ minutes each day, the adds approximately \$24.3\$ hrs extra each year, means that we need to remove a work every single year, not include one.

What does being \$4\$ minute ahead/behind median for the year?

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edited Mar 21 "17 at 11:29

Qmechanic♦
request Mar 20 "17 at 18:10

JayembyJayemby
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There seems to be some confusion. The variety of solar work in a year different from the number of sidereal days in year by 1--that distinction of course being due the 1 change around the sunlight per year influencing the solar day.

Back to the number of days in a year: Baring tidal resonances, there is no factor for the length of a work to it is in commensurate with length of year; that is what is it: 365.2425

I remember this as follows:

365 job in the year

+1/4 A leap year every 4 years

-1/100 other than on years ending in "00"

+1/400 unless the year is divisible through 400 (e.g. Y2K)

365.2425

so the 2000 to be a leap-leap-leap year.

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answer Mar 20 "17 in ~ 19:32

JEBJEB
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4 minutes a day accumulates to 24.3 hours in a year - ie the moment it takes for the earth to turn once, an ext or less. This in essence is why the difference in between the sidereal day and the solar day is 4 minutes.

It has actually nothing to carry out with leap years. This arise because the earth"s orbital duration is 365.2422 days. So we have add a day come the year every 4 years, so that things don"t go adrift too lot - but that over-corrects, therefore every century, the leap year is omitted. Yet then this walk a little bit too far the other way, so actually every 400 year (eg 1600, 2000) the century year does have a leap year. This it s okay pretty close to 365.2422.

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edited Mar 20 "17 at 20:19
answer Mar 20 "17 at 19:03

Dr ChuckDr chuck
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Very roughly: we comprise the four minutes via our passage around the sun.

23hrs 56mins rotation that the planet keeps the stars in the same location each sidereal day; 24hrs rotation the the earth keeps the sunlight in the same location in the skies each solar day. We"re moving roughly the sunlight over the food of the year, so we have to add a couple of more minutes to account because that that.

The four minutes are relevant for things choose satellites, which just care about rotation around and of the planet, yet for calendar use they are not necessary as our calendar is based upon where the sunlight is in the sky.

All this method that you deserve to safely ignore the sidereal job for many purposes; as such, the four minute distinction has naught to perform with leap seconds and such, which room all characterized in terms of solar days.

When us say "365.25 days" i beg your pardon day are we talking about (sidereal or solar)?

Solar days!

This is usually "random"; over there is no (substantial) link between the length of a day and also the size of a year; we"re spinning as we go about the sun, and also it would certainly be quite the co-incidence if we occurred to be back to precisely where we began in spin in ~ the same time we"re back where we started in orbit.

(This in reality can and also does take place as a an outcome of orbit resonances, the many famous instance being the moon which is almost totally tidally locked. But hey.)

The extra 4 minutes 1 of a day is just down to that, nothing to perform with the sidereal offset.

My teacher claimed that the 44 minutes we acquire from the solar job being longer than the sidereal day led to the 0.25 (ish) more, which reasons February 29.

This is noticeable actually, since 44 minute is nowhere close to quarter the a day.

Less waffly an introduction from Wikipedia write-up on Sidereal Time:

Sidereal time is a time-keeping system. That is offered by astronomers to find celestial objects. Making use of sidereal time it is feasible to suggest a telescope come the appropriate coordinates in the night sky.

Sidereal time is a "time scale based on Earth"s rate of rotation measured loved one to the addressed stars".

Because the earth moves in that orbit about the Sun, a mean solar work is around four minutes longer than a sidereal day. Thus, a star shows up to rise four minutes earlier each night, compared to solar time. various stars are visible at different times the the year.

See more: What Is 1/6 Divided By 2 /1? Mathematician Explains The Correct Answer

By contrast, solar time is reckoned by the motion of the planet from the view of the Sun. An average solar work (24 hours) is much longer than a sidereal work (23 hours, 56 minutes, 4 seconds) because of the amount the earth moves each day in its orbit approximately the Sun.

There are additionally some good existing answer on ridge Exchange the say the exact same thing in different ways (so, if you check out them all, you"ll have gained it!); because that example:

And, finally, a valuable illustration: