by Theodore R. Frimet
The Weight of Water
fundy tides, tidal friction, and Einstein
I ordered a copy of the Observer’s Handbook 2019, back a few months ago. I was pretty stoked that The Royal Astronomical Society of Canada (RASC) had produced its first USA Edition, ever. However, I did it on the cheap, and thanks to a fellow UACNJ member, we ordered a few at a savings. The money saved, however, translated into weeks doing without the guide. I was in no hurry to “jump” to Jenny Jump to pick up my just rewards. My copy lay dormant in the club library, for weeks on end.
The night before I started out for a volunteer site at Blairstown Library, for Makers’ Day, I spied last years 2018 Handbook on the kitchen table. Woa is to me! The 2018 edition would not have the many tidbits of data to answer the many, and exhausting questions that the little tykes would brew up for this amateur. What to do? Put the angst, and anxiety to the side.
I settled into Makers Day. Hundreds passed me by, to visit the arrangement of tables and projects. Many to make granola, or to be wowed by the aluminum 1950’s weavers station. However, I was not even bested by the laser cutter being demonstrated, that day. Proud to be an Amateur Astronomer, I report back to you that not less than 15 adults, and 30 plus children stopped by our wee little habitat.
I be armed with a 12 inch Dobsonian, 6 inch Celestron Newtonian, and 8 inch SCT, books, charts, and binoculars. Hands on for all-comers, all-ages. No exceptions! We had a variety of experiences. They ranged from the youngest trying out the old dob as a merry-go-round, to the many gilded faces looking down at young Newts’ mirrors.
The best personal experiences, however, were in the free books being handed out. They were the former pride and joy of a former Astro-Physicist, turned fusion laser tokamak researcher, now one year retired. And many of his former books hit their mark. Two tomes,which were written in Russian, found their way into a second generation American home, where Mom spoke English as a second language. And yes, Russian was her first. She was stunned how I knew intuitively that the family spoke Russian, and that the boys were so happy. She asked me how I knew? Did I know Russian? I said, “dasvidaniya”. She said, “ok”. I hope I didn’t offend her, as it is probably the ONLY Russian phrase or word that I can passably speak. She smiled. And eventually left the Makers with two happy, and hopefully, future Astro-Physicists in tow.
I look down, now, at the table, and recall why I am writing this essay. The weight of water. I began reading the RASC handbook, yesterday afternoon, while at Jenny Jump. I felt it was a decent way to pass the time, after Makers Day. I curiously turned the page to the ever present article written by Roy Bishop. It is titled, “Tides and the Earth-Moon System”. Roy, unfortunately, writes a little on the long side. He must be a relation of mine, as some of his sentences exceed 50 words, or more. Very tough on the fore-brain. And ultimately, this information is quick to be brain dumped into the sump that holds the overflow of water. Wait. Read that back. Count the words. 19 words. Two more than would be necessary to make a simple sentence incoherent and impossible to absorb. I give pause to my ill gotten comments. Mr. Bishop, I apologize to thee.
Janet cautioned me not to be unruly. In my own experience, I have seen that the pot need not call the kettle black. I reap what I sow. Karma is king. Someone call my editor and complain. Ok. Let’s move on, now.
What you will read is part one of three. And I will not offer you parts two, or three. You can get that from the RASC Observers Handbook 2019, pps 179-183, courtesy Roy Bishop. If you dare. Well, in my Dale Carnegie training, this is called ‘throwing out the gauntlet’. Or is that me smacking you with a glove? I forget. You would do well in heeding my advice. Buy a copy of the USA Edition, RASC Observer’s Handbook 2019. Every Amateur Astronomer, should have a copy at the ready.
The moon exerts Newtonian gravitational forces onto our Earth. The wet part of our world, that is closer to the moon, accelerates towards the moon. That force is greater than the force that accelerates our world, below the water. Yup. You read that right. That creates a bulge of water, that faces the moon.
There is another bulge. It is on the “far side” of the Earth. That is the Earths face that is farthest from the moon. That gets less force. It is almost as if that water is being left behind. Wait a minute. It is being left behind! It bulges out, behind the Earth.
Recap. There are two bulges. One out front of the Earth, facing the moon. And another, lagging behind the Earth, farthest from the moon.
And get this. The Earth rotates below the bulge. So the tide ebbs and flows over the Earth, as the Earth goes about its daily 24 hour rotation. I think that this might explain why closed salt water seas and fresh water lakes do not have “tides” like rivers and oceans. You can comment, here, if you like. Pause. I look up at the ceiling. I am seeing if any of this is sticking. Yes. There it is.
Old Sol also exerts a gravitational force on the Earth. This too affects the tidal forces. Since the Sun is so much farther away than the moon, this force is much less. Yup. Even though the Sun is so massive, it still has a far weaker affect on tides. Distance is everything, now-a-days. The force is counted as the square, and sometimes, in variations, as the cube of the distance. (argh – cubes, squared, pi-rrr-squared!)
But get this. The two tidal patterns (the sun’s and the moon’s) aren’t happening at the same time. At least not always. And when they DO synchronize, we have even higher tides! Happy is the amateur that understands the weight of water. Go now and do our bidding, and pass the good word that centrifugal force is a myth, and that water weighs in. Newton would be proud.
There is much more. Fundy Tides. Tidal Friction (my favorite). And General Relativity and Tides. However, I want you to have access to the indisputable facts and figures from the handbook. And if I’ve whetted your whistle, me thinks that you will be reading from the latest edition in no time, soon. Thank you, Editor James S. Edgar, for bringing us the Observers Handbook 2019, USA Edition.
Author side note: “if you appreciate gravitational forces on our earth, then it is not a quick leap of faith, in your understanding, and in our mentoring path, to comprehend that there are many tidal forces in the universe; always playing a role in the compaction and distortion in the play-dough like consistency of minor and major planetary bodies, stellar bodies, and yes, dare I say it, ever eerily to speak its name. Yes, black holes.” Oops. Word count = 70. Very weighty.