Originally posted by alfa1
Originally posted by Sovaka
However, according to Earth, it takes 23hrs, 56mins and 4 seconds to complete a single turn, which gives us a time discrepancy of 236 seconds or 3
minutes and 56 seconds.
Its the difference between sidereal and solar time.
Sidereal - the actual time it takes for the earth to turn, relative to the universe = 23hrs 56mins.
Solar - the time it takes for the sun to go from noon to noon = 24 hours.
The difference is because the earth is orbiting the sun, and that makes the sun a "moving target" with respect to the earth rotation.
In the 23hrs 56 minutes that it takes the earth to turn, the earth has also moved along a bit in its orbit and it needs an extra bit of time to turn a
bit more for the same part to face the sun.
So... it depends what you're interested in.
If you're as astronomer, you might have more of an interest in Sidereal time. If you want to meet friends for lunch, you'd better pay attention
to Solar time.
edit on 16-1-2013 by alfa1 because: spellinh mistakez
Excellent Explanation! Did everyone not read this and do some research???
(Is the original post a joke, or the response? Or just possibly misled)
We are not off by a huge amount years. geesh people. Look at the definitions. You are talking about two different scenarios.
A Day is defined as the time it takes to spin on it's axis ONE time in relation to the SUN. NOT in relation to space itself (the universe). A day
is 24 hours exactly. Noon to Noon is 24 hours.
What the OP is referring to by mistake, is the time it takes to spin around (as if it is not moving). If the Earth were to stop rotating around the
sun and just spun by itself in the universe, it would not be 24 hours. HOWEVER, the earth is spinning and rotating around the sun. And so it takes
more time to catch up which equals 24 hours.
As an example. Picture a protractor where The earth is a ball is at the Edge at the 0 degree position, and the SUN is in the middle. Note the start
point of the ball where it face the center of the protractor. If you spin the ball in place, without moving, that would equal the "less than 24
hour day". Now, at the same speed, if you spin the ball while moving up in degrees on the protractor, it will take longer in order to get back where
the start point is directly facing the center, i.e. 24 hours for a real earth day.
So in terms of a day, a day is a day is a day, which is 24 hours.
Now for the calendar year, YES it is off, but at most no more than 1 day. We approximate 365 days, but we are off by a couple of hours. Over the
course of 4 years, we add a day, to account for this. We are never more than 4 years off from a true year, and never more off than 1 day. Hours
off, yes, but not more than one day.
Now in terms of time overall. Time is just what us as humans used to perceive WHERE WE ARE in the UNIVERSE, and possibly when. Forget about time as
3:45, but think more of where the sun is, and what season it is in. If we know that the SUN is the highest at a certain time, and does this
repeatedly, then we can log that, and divide that, which is where we got the importance of hours.
It was also important to keep track of the days or year to know when to GROW food, or prepare shelter. You can take where the sun rises and sets each
day and make a mark, and pretty soon you find the summer and winter solstices. From there you can backtrack to the number of days in a year, which is
useful and important.
Yes we as humans dictate our work lives by time, and I can see why some would think that time is made up. Like Why wake up at 6am? eat breakfast at
7am? work from 9am-5pm? I would like to RE-PHRASE that, and say that TIME is real, but that our social activities and what WE as humans do with time
is what is FAKE. Because all time is, is just the relation of our planet with the sun or stars, adn that is REAL. Whether we count how many times
it goes around the sun, doesn't matter, because it does go around the sun multiple times. Whether we divide the amount of time it takes for the sun
to come back, doesn't matter, because the sun always will come back.
so overall Time is important and real. Humans are just measuring it using different factors. We as a species are just choosing to do things like
ANTS according to certain dividends of time, but blame that on social factors, not on time itself.