Why dont we see the effects of the Leap Year over the 4 year period?

Question

The calendar day has 24 hours, whilst the Solar (Astronomical) day is exactly 23.56mins long. After 6 months you would have lost 12 hours (half a year =182 days * 4 / 60)

Therefore based on these simple caluculations, we would be 12 hours ahead of ourselfs. Where Day would be Night and Night would be Day? How comes we dont see the effects of this?

Also based on this accurate solar day of 23hours. 56mins, wouldn't we be gaining a day every year?

Answer 1

Very good question... your confusion lies in comparing two distinct measurements

First: A standard day is defined with respect to the position of the Sun in the sky (alters through the year, but averages around 24 hours/day)

The 23h 56m time refers to one "true" rotation, and the relative position of a point of reference on the Earth compared to other astral bodies (called Sidereal time, see first link)

As the Earth rotates counter-clockwise (in a counter-clockwise orbit) the time taken for the Sun to come to the same position in the sky is longer than the time taken for the Earth to rotate once around itself - this is not always easy to understand, you may need to use a model to visualize it (see last link)

Though other objects are affected by this change (star measurements and such), the Sun's position in the sky at noon is roughly fixed (because we orbit the Sun, not them).

So, we really don't "gain" those 6 minutes with respect to the Sun.

Leap years are needed to correct the fact that the time between two successive vernal equinoxes (one year) is not a nice divisible number (365.2422 days as opposed to 365)

Answer 2

Pe = 365.256366 days Pm = 87.9691 days Psyn = 1 / ( 1/Pm - 1/Pe ) = 115.8772 days N = int[ int(Pe) / Psyn ] = 3 T = int(Pe) - N Psyn = 17.3684 Mercury can be at inferior conjunction 3 times, if the first conjunction occurs between 1 January and 17 January. Mars has an obliquity (axis tilt) of 25.19 degrees, which is about the same as Earth's obliquity of 23.5 degrees. If Earth lost its magnetosphere, compasses would not work, birds and bees would be confused, and dangerous speedy charged particles from the sun would harm living things on the planet's surface. Go to the beach with a pot of water and a thermometer. Make a fire and boil the water in the pot. Put the thermometer in the water and measure its temperature while it is boiling. Next, go up on top of a mountain with the same experimental apparatus and do likewise. Note that water boils at a lower temperature. The significant difference in the laboratory conditions is the fact that the air pressure is lower on top of a mountain than it is by the beach. You might conclude that water would boil at even lower temperatures if you could go even higher. In fact, you might could reach a place where the air pressure was so low that water would boil into vapor the moment it stopped being ice. At that pressure (or less), then, water-ice sublimates directly into vapor and has no liquid state.

Answer 3

Imagine viewing the solar system from high above the north pole of the earth. From this perspective, the earth both orbits the sun and rotates on its axis in a counter-clockwise direction.

Earth has two types of rotational periods, sidereal (with respect to the stars) and solar (with respect to the sun). The stars are so far away they can be considered to be always in the same direction from earth no matter where the earth is in its orbit - but not so with the sun.

During one day the earth moves about 1/365th along its orbital path. The direction to any particular star from one day to the next is always the same to a high degree of precision, but the direction to the sun is not!

You have the sidereal and solar days reversed in your question: it takes 23h 56m for the earth to turn and face the same star, but another 4m /day to turn enough so that the sun reaches the same position in the sky as the day before. The earth has traveled just under one degree around its orbit in a day, so the angle to the sun has changed by that much.

If you divide 1440 minutes/day by 365.242199, the length of the average day over 400 years, you get 3.942589 minutes, or 3 minutes 56.56 seconds - the difference between the sidereal and solar day. Happy New Year!

Answer 4

Do me a favour! It;s New Years Day and half of us are still hungover!

Answer 5

we do but it happens so gradually we don't notice. Unless ne1 is sad enough to time it... sorry if u did time it

Answer 6

Oh my god he's right aaaggggggghhhhhhhhhh.

Answer 7

get out more. good question tho'