Earth’s time is strange
Thursday, September 1, 2016
Is there a friend of yours who stays with you 24x7x365? No, maybe not even your best friend. If your friend truly had your back, he would stay with you for, 24.0000006x7x365.24291. Well don’t get confused, this is time.
George Washington was born on February 22, 1732. That’s what we were informed but his family bible says that he is born on FEBRUARY 11, 1731/2. So which is correct? Don’t even ask about 1752. In Russia, it seemed like a normal year but in the British Empire again everything seemed fine except SEPTEMBER, the second was followed by the fourteenth. What happened in those 11 days? You got tangled again. The problem is with time to question and the movement of the earth. Reconciling these two things, we can draw some strange observations.
As viewed from the North Pole the earth moves counter clockwise. We just don’t rotate, we even revolve on a plane tilted 23.40 relative to our spin. Rotation causes your sunrise, noon and sunset.
Investigating more… let’s talk about meridians. You are on one at his moment. Meridians are longitudes which lay from the North Pole to the South Pole. When your meridian is exactly below the sun, a cool thing happens… all the shadows around you point towards one of earth’s poles, unless you are on the sub solar point. It is the point on the earth’s surface where the sun is directly overhead, that is where the sun’s rays are hitting the planet exactly perpendicular to its surface. It is always there somewhere. On the subsolar point, your shadows fall directly below where they can easily disappear.
Due to the earth’s tilt, the subsolar point changes always. Twice a year, the subsolar point touches Hawaii. When it crosses Hawaii, it is known as Lahaina noon meaning ‘cold sun’. Straight vertical objects look unnatural because their shadows disappear. It looks as if someone took a picture of a vertical object and kept it in the real picture.
Once every rotation the subsolar point crosses through somewhere on your meridian making the noon (for you). The technical name for noon (for you) is local apparent solar noon. The clocks you have don’t tell your local apparent solar time because long ago we realised that if every meridian had its own time, a person just a few kilometres away from you will see different shadows than you did and disagree with your time. To overcome this problem, towns adopted their own time. This was standardized as time zones as we know today.
If we explore more deeply, we have to begin by asking, what’s a day? We know the answer. Obviously, it’s the time, the earth takes to complete one rotation. It is almost correct. For far away fixed stars, a meridian completes one rotation in 23.9 hours. This is known as a sidereal day. Sidereal means pertaining to the stars.
Even though this concept seems pretty clear, our clocks and calenders are not based on. This is because of a nearer star’s position relative to our position, the sun. After every sidereal day, a meridian has to move a bit more to face the sun. This longer definition of a sidereal day is what the modern clocks and calenders are based on. It is called the solar day. The time required for a meridian to point back the sun again changes day to day. Our clocks are only based on the average, 24 hours. The changes have led to make June 21st a minute longer than December 22nd.
One minute is not going to make any difference. Just sit back and enjoy the movement of the universe without dividing it and calculating it. Earth’s movement can cause differences in time so lets accept them. Even though one minute is not going to make any difference, time is precious, we can never get back again.
(Reference Material:- Youtube- How the earth moves by Vsauce, and Google)
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