Ranger Steve’s Nature Niche
By Ranger Steve Mueller
If you desire to weigh less, weigh yourself when the moon is overhead or even better when it is a New Moon. When the sun and moon are both on the same side of the Earth during a new moon, they exert greater gravitational pull together and make you weigh less. Tides are highest when the gravity from both pulls toward them. You will weigh your least when the sun and moon are directly in line. The opposite side of the Earth experiences high tides at the same time. This results in high tides every twelve hours. Unfortunately, our bathroom scales do not measure fine enough to actually show how much less you weigh. It is only a fraction of a pound.
The Perseus Meteor shower article two weeks ago took precedence over the moon’s gravity because it only occurs once annually. We experience moon cycles monthly. The Perseid meteor shower peaks about August 11-13 but we can observe increased meteors for a greater time about a week before and after peak.
I have read the moon’s gravity is not great enough to create tides in the Great Lakes because the size of the lakes is too small but my observations do not agree. It is well known that tides in oceans raise and lower water by several feet daily. In the open ocean it is not observable, but along the shore, water retreats great distances when the sea floor slope is gentle. If the coast drops abruptly, it is still noticeable but one must look at the nearly vertical cliff walls. Sea wall life becomes visible for several hours before the water rises again.
I observed a tide in Lake Michigan near Manistique in the Upper Peninsula. We lived there for a couple years when the girls were little. We would frequently walk the mile to the lakeshore with wagon in tow just in case the girls became too tired.
The lake surface was as smooth as glass on a warm summer night. A full moon worked its way to zenith. Dolomitic limestone slabs of flat rock peppered the shallow water near the swimming beach. Some of the flat slabs barely protruded above still water. Rocks made an inviting stepping-stone trail to a large rock that rose several feet above lake level. We walked on the dry slabs to the big rock and sat to enjoy the evening. It was a movie quality evening. We had the lake, quiet, beauty, and the distance sounds of nature from the shore all to ourselves. It was a choice family evening.
We sat on the rock as the moon moved overhead. A Great Blue Heron fed in the shallows to the west. Ring-billed and Herring Gulls walked the beach gathering food morsels in the dimming light as day became night. The moon was bright enough to create shallows of our silhouettes. Aquatic insects skimmed the shiny water surface. We looked for fish but I do not recall if we saw any. I guess it is good reason to pull my daughters away from their busy lives and take them back to look for the abundance of life and see if we can observe fish. Life thrives in the water, on the surface, and above it. I know fish must be present or the heron would not have been wading and hunting.
When we decided it was time to walk home, we planned to walk on flat rocks used to reach our high rock perch. Most were now under water. Moon’s gravity had drawn Lake Michigan closer. The surface of the lake was higher but unlike large ocean tides, Lake Michigan had risen about a half inch. It was enough to submerge several of our stepping-stones. I did not have a millimeter ruler to measure the change. I should have gotten a dried grass stem to determine the vertical lake level change. It is another reason to return so I can measure how high a rock protrudes at low tide twelve hours earlier and then measure how much it is submerged when the moon pulls Lake Michigan closer. Take your family outdoors to observe and experience wonderful everyday nature phenomena.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at firstname.lastname@example.org – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.