Are You Sure Your Birthday Is When You Think It Is?

When is your birthday this year?  You could be celebrating your birthday a day too early, or perhaps a day too late. Our custom is to celebrate (or lament depending on your age) our birthdate every year, which is  essentially celebrating the earth making yet another revolution around the sun (the “solar" calendar).  

The problem is that the earth doesn’t make a full revolution in 365 days….our traditional calendar falls short by 6 hours, 11 minutes and 26 seconds.  That means that if you were born at 9:00 and night, your birthday on the solar calendar  (when the earth returns to the same exact spot) is technically 6 hours later, or 3:00 am the next day.  You celebrated your birthday too soon! 

However, if you happened to be born on a leap year, then when your next next calendar birth date comes around, you are actually one year and one day old (the earth has already passed by the original spot of your birthday).  Hence, your birthday on the solar calendar was yesterday!

Now you say, hold on a minute.  Doesn’t this average out year after year, adding the leap days every four years?  The answer is: yes, mostly it does.  Your calendar birthday keeps sliding later and later compared to the solar calendar until the leap day jumps ahead to catch up.  Unless you were born on a leap year, then your birthday is technically a day too early and it keeps sliding back closer and closer to the actual solar birth date until leap day leaps ahead again. 

The calendar we traditionally use (at least us here in the western civilization) is called the Gregorian calendar.   It was Julius Caesar who created the Julian calendar, which attempted to synchronize the calendar with the solar calendar by adjusting for those missing 6 hours and adding a leap day every four years. 

Unfortunately, the Julian calendar did not compensate for the missing 11 minutes per year.  By the 1500’s, those 11 minutes accumulated to the point where the Julian calendar and the solar calendar were off by as much as 10 days. This problem had religious overtones since the relationship between the date for Easter and the spring equinox were significantly out of sync.  In 1582, Pope Gregory XIII (i.e. the "Gregorian" calendar) unveiled a new calendar which made an adjustment for those missing 11 minutes by skipping a leap year in three out of four century years.

 ANSWER TO TRIVIA QUESTION:

In 1752, England was still using the Julian calendar whereas the rest of Europe had been using the Gregorian calendar.  By then, England’s calendar was off by nearly 11 days.  Hence, Parliament voted to follow Wednesday, September 2 with Thursday, September 14.  Nothing ever happened in England between September 3 and 13, 1752…those dates didn’t exist.

Unfortunately, we are not done yet….one more adjustment is going to need to be made.  To be exact...the solar calendar and the Gregorian calendar are still off by 26 seconds per year.  We are going to have to add another leap day by the year 4949.

Somebody mark your calendar will ya?

How to Point in the Direction of Earth’s Orbit

Quick!...walk outside and point in the direction of earth’s orbit around the sun.  Can you do it?  Come now, the earth has been orbiting the sun for billions of years…and certainly for every year since you were born.  If you were in a car going 65 miles per hour, you could point in the direction you are heading.  Why can’t you point in the direction that your own earth is heading, particularly when you consider we are orbiting at a rate of nearly 67 THOUSAND MILES PER HOUR around the sun!

(And to the 25% of Americans who didn’t know this:  YES, the earth orbits the sun, and not the other way around).

So how do we figure our direction of travel?  Here’s how:

Assume for the moment you are standing at the equator.  

In the early morning, when the earth rotates around so that the sun is just barely visible over the eastern horizon (i.e. “sunrise”), point straight up.  THAT’s the direction of our orbit.

Or, at high noon, with the sun directly overhead, point due west just over the horizon.  THAT’s our direction of travel.

Direction of Earth's Orbit (at the equator)

At “sundown”, when the sun is just barely visible on the western horizon, point straight down towards the center of the earth.  THAT’s our direction of travel.

If your are not on the equator, but instead in the northern hemisphere for example, then you need to adjust where you point.

At "sunrise", don’t point straight up, you are just pointing to a random point in space.  Instead, face due south (the sun over your left shoulder) and point halfway between the horizon and straight up.  This is roughly the direction of travel.

At high noon, point due west.  This is close enough.

At “sundown”, point to the ground about halfway between straight down (center of the earth)  and due north.

For Southern Hemisphere folks, the process is similar only swapping south with north, etc.

DISCLAIMER:  The earth is slightly tilted on our axis as we continue our 24 hours of rotation. Hence, some adjustments to your pointing direction may be required.  This is why the above pointing directions are “close enough”.

Now here is a real challenge, of which I am still working on:  What direction do you point when you are standing at the North Pole?  There is no east or west…there’s only south.  And some periods of the year when the sun never even “sets”.  How do you figure our orbital direction?

Stay Tuned…

How Fast are you Standing Still?

With our earth spinning and orbiting the Sun, and the Sun and Milky Way moving around in the universe, how fast do you think we’re traveling just standing still - all in?

a)  A little over 67,000 miles per hour

b)  More like 200,000 miles per hour

c)  Nearly 2 million miles per hour

d)  Zero miles per hour…I still believe the earth is the center of everything

e)  It’s all relative…you have to ask your brother or aunt or something

f)  None of the above - I only work in Kilometers per hour.

The correct answer is c) nearly 2 million miles per hour.  However, if you answer was e) you can claim partial credit (but not about the brother or aunt).   When everything is moving, and I mean everything including space itself, how do you measure any speed at all?  Compared to what?  Hence it is relative.

Scientists believe that space itself is still expanding, based on something called the cosmic background radiation.  They can use the rate of expansion of this cosmic radiation stuff as a frame of reference to calculate our own galaxy’s speed through the universe.

Anyway, let’s add up what we believe is our total rate of travel:

Earth’s Rotation Speed (at the equator):                          1000 MPH ⁽¹⁾

Earth’s Orbit speed around the Sun:                           67,000 MPH

Sun’s Motion within the Milky Way:                              43,000 MPH

Sun’s Orbit about the Milky Way Galaxy:                   483,000 MPH

Speed of the Milky Way Galaxy through Universe:  1,300,000 MPH

                                                                Total:  1,900,000 MPH

Almost two million miles per hour!  For reference, the speed of light is 671 million miles per hour. Hence our measly 2 million miles per hour is rather insignificant compared to the speed of light ⁽²⁾.  

This raises the question whether you can ever be at absolute rest - not moving at all (I bet that question was in the back of your mind wasn’t it?).  I once tried to be absolutely still and vegetate  on the couch watching a baseball game.  It didn’t work…this orbital speed nonsense kept getting in the way.   

There are numerous web sites on this subject.  Here is a particularly good reference:

http://www.astrosociety.org/edu/publications/tnl/71/howfast.htm

Notes:

(1)  If you don’t happen to be at the equator, then your rotational speed will be less - such as 700 MPH in the Northern or Southern Hemisphere.  Of course, at the North Pole, your rotational speed is zero.  You are not traveling any distance…just rotating in place at one revolution every 24 hours or so.

(2)  However, Einstein theorized (and is adopted as truth today) that the speed of light is the same to you regardless of what speed you are traveling…so figure that one out.

Some Help in Pointing in the Direction of Earth's Orbit

***SIGH***   It has come to my attention that many of you, in reading my first earth blog on How to Point in the Direction of Earth's Orbit, are unknowingly pointing in random directions of space...directions which the Earth has no intention of traveling.

To provide a little guidance on this, I have provided below some photographs which I took today showing the proper directions to point.  Please feel free to use these pics as reference.

Direction of Earth's Orbit at "sundown"

Direction of Earth's Orbit at "sunrise"

Direction of Earth's Orbit at high noon.  (Direction is at the horizon between those two trees)

I hope these help.  Happy Pointing!

Earth's Weather: Going in the Wrong Direction?

How come weather systems in the U.S. never come from the northeast, pummel the northeast coast with rain, then travel west across the continent dumping snow on the Alleghenies, then combine with a Nor’wester from Canada and dump a bunch of snow on the Rockies, and finally combine with a southern Pacific hurricane system to dump a whole ton of snow on the west coast…mostly San Francisco up to Seattle??? (us Southern Californians don’t really want all that much weather…it would ruin the avocado crop and make poor guacamole dip).  

Instead, weather systems travel west-to-east.  But the earth is also rotating from west-to-east at speeds up to 1000 miles per hour.  Hence these weather systems are traveling even faster than earth’s rotating speed.  What gives?  Why would weather system travel eastward faster than earth’s rotation speed? Is it due to mountain ridges pushing the air?  Did someone on the east coast do something to anger the gods?  Is it the same in other parts of the earth?  

I would like to think that it is due to us folks on the west coast doing whatever it took to appease the gods (including making excellent guacamole dip).

However, in researching this more closely, I found that weather systems have several reasons for traveling west-to-east: 

a)  The sun heats up the east before the west (remember: the earth rotates towards the east - so the east coast is getting heated by the sun before the west coast.  Hence, cooler air from the the west tends to travels towards the east.

…but more importantly…

b)  The air at the equator is traveling with the earth (which is spinning at 1000 MPH).  As that air heats up and rises, it moves northward (or southward), moving over regions of the earth which are rotating at a much slower speed (say 600 - 700 MPH).  Hence, the hot air at the equator ends up traveling faster than earth’s speed at locations away from the equator.

So there you have it...there are good, technical reasons for weather systems to travel from the west to the east across the entire earth systems. 

And it has nothing to do with good guacamole dip...but I think it helps.

Some references & reading to consider:

http://www.srh.noaa.gov/jetstream/global/jet.htm

Why Does the Earth Spin the Way it Does?

The earth rotates west-to-east; counter clockwise looking from the north pole.  Of course, some alien flying through space could easily approach the solar system from our “south" pole, and see us spinning clockwise.  Nevertheless, why do we spin the way we do?  Why not spin east-to-west, or why spin at all?  

It turns out, it’s quite simple:

• A cloud of cosmic stuff 4.5 billions years ago gets hit by something; perhaps a supernova

• The cosmic stuff collapses into itself due to strong gravitational pull

• To conserve the energy, the cloud begins to spin (called angular momentum); the smaller the cloud gets, the faster it spins (e.g. a skater pulling arms inward to speed up the spin)

• The cosmic stuff starts to combine; collide; and stretch to eventually form the solar system

• With no resistance, the solar system, including the earth, continues to spin (“…an object in motion tends to stay in motion”).  However, the earth’s spin is slowing due to the moon’s pull.  Millions of years ago, the earth took only 22 hours to complete a rotation…and a million years from now, it will eventually take 26 hours.

• Don't like the way we spin? Try moving to Venus - it takes 243 earth days for Venus to complete one rotation...and it spins in the opposite direction!  Or perhaps Uranus  - - it rotates on it’s side (the axis pointing towards the sun).

Well, maybe it's not all that simple…but it puts an interesting spin in things, doesn't it?


Read more at: 

http://phys.org/news105637304.html#jCp
http://spaceplace.nasa.gov/review/dr-marc-earth/earth-rotation.html
http://phys.org/news105637304.html

http://www.universetoday.com/14491/why-does-the-earth-rotate/

Is there a Center of the Universe?

                                                                               NO.