The Eastward Wobble, The Dance of the Earth


In April of this year NASA released findings related to the Earth’s melting ice sheets. Often when the gringa things about climate change, warming temperatures and melting ice sheets, the only thing I consider is how sea levels will rise. It never occurred to me that ice sheet disintegration may result in a more wobbly world.

Think about the traditional children’s toy, the spinning top. It’s a bit like our world. As it slows its spin it begins to wobble. As ice sheets melt and the balance of Earth begins to shift, we will, indeed, experience a global wobble. Scientists officially define this as a “periodic wobble and drift of the poles”. All the gringa wants to know is, “What exactly does this mean for me? Am I going to fall on my patootie trying to walk to my car?”

NASA asserts that over the past sixteen years Antarctica and Greenland, combined, have averaged about 400 billion tons of ice loss annually. Before the year 2000, as Earth spun on its axis it had a gentle drift toward Canada (westward). Because of ice loss, now the drift is about 75 degrees in the opposite direction, eastward. This happens because as ice converts to water and moves elsewhere, the distribution of Earth’s mass changes. What this means exactly is that the location of the North and South poles will change. In other words, Earth’s axis is relocating.

Now, the traditional location of Earth’s North Pole may have to be renamed to the Northeastern Pole. Earth’s axis is like an invisible pin stuck through the Earth from North to South. The Earth spins on the tip of the pin, rotating with a slight wobble that is normal. However, if the geographic location of the Poles change, complete topographical and satellite telemetry systems have to be adjusted to accommodate this change. For the average person, this means that your GPS is going to deliver you to the wrong place!

Scientists have long known that the Poles shift by a few centimeters from time to time as a part of Earth’s natural climate adjustment cycles. But what we are dealing with now is much more dramatic. Experts estimate that the shift is averaging about ten centimeters Eastward annually. Our great-great-grandchildren may have to adjust Christmas stories to have Santa Claus living in Russia or Norway.

Although scientists understand that as ice continues to melt the Earth will adjust by shifting its axis to the place where it has lost mass, even their best predictions are really just a guess. This is an extremely complex problem. It’s not just melting ice sheets that affect the process but also loss of groundwater in above ground reservoirs and underground aquifers (which underground aquifers cannot be accurately measured) as well as glacier melt and glacier movement. Many glaciers float about the ocean as they please.

The Earth’s ice and water storage formula affects polar drift. Yet many of the variables in the formula cannot be measured or can change their individual affect. So, scientists are left scratching their heads, doing the best with what they’ve got, and hazarding their best guess on what humanity can expect.

Ice melt is not the only thing that can bump the North Pole to a different location. Enormous earthquakes and devastating tsunamis can do the job as well. Indonesia’s great earthquake moved the North Pole eastward by about 2.5 centimeters and also lengthened Earth’s day cycle by 2.68 microseconds. No wonder I’ve been so tired lately! The gringa is filled with wonder at how humans remain at the mercy of nature despite all of our technological advances.

Sources: www.nasa.gov

news.nationalgeographic.com

Image Credit:  www.worldatlas.com

 

 

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A New Moon For A New Age


Most people think Earth’s moon is old news. However, what the public may not realize is that NASA has a rover active on the Moon, the Lunar Reconnaissance Orbiter Camera (LRO). The gringa will call the rover “Elroy” for your reading pleasure.

Elroy has a new exhibit on display at the National Air and Space Museum in Washington, D.C. that reveals that our Moon is anything but boring. What with Mars and black holes and parallel universes getting so much attention, it’s easy for our little ol’ Moon to get lost in the mix. The gringa wants to give it some glory that is long overdue.

One thing that is interesting about the Moon is that it undergoes such frequent change. It seems to get blasted all the time by meteors and such. The images on display in the exhibit show the formation of new impact craters (kind of scary when the gringa considers its proximity to home! The Moon may very well be our shield!). Recent volcanic activity has also been detected. And, most curious of all, is evidence that the Moon’s core may be cooling which has caused it to shrink and crack the crust of the Moon’s surface.

Elroy is a busy little rover. So busy, in fact, that there are too many images for this single exhibit. So, in addition to the favorites that were selected for display, there is a large screen which projects lunar images that are updated daily.

Since 2009, in addition to a fabulous photography collection, Elroy has also collected environmental and geological data with the seven other instruments he is equipped with. Elroy’s mission is to map the entire surface of the Moon. Even the legendary “dark side” of the Moon.

You see, one reason the Moon remains so mysterious is because it has a “backside”. Yes, we never get to see the Moon’s rear-end. We always see only one physical side of the Moon. Now, this is not because the Moon hangs suspended in space and never rotates. It’s just that it has a rather peculiar rotation cycle.

Millions of years ago the Moon spun around much faster. The pull of Earth’s gravity has caused it to slow down. So much so that its rotation cycle now matches its orbit cycle.  These cycles take 27.3 Earth days. However, observed from Earth it takes 29.5 days. (Don’t expect the gringa to get into that mystery here! You can research it yourself by clicking on… Understanding the moon phases). So, since the orbit and rotation cycles are exactly matched, as the Moon travels about the Earth, at night, when we see it, the same side is always presented to Earth.

However, for serious stargazers with top-notch telescopes, you can get a peek at a sliver of the hidden aspects of the Moon. Since the Moon is not “round and flat” like a coin but is actually elliptical, like a ball, at just the right time there is a speed differential when the Moon is farthest from Earth, thereby its rotation speeds up a bit because of a little less gravity drag. This causes what scientists call a “rocking” motion and an extra nine percent of the Moon’s surface is visible. But now, thanks to Elroy, all Earthlings can see just exactly what is on the Moon’s backside which is not “dark” after all, except during the cycle of a full moon when the Earth is blocking all sunlight.

Only two years into its mission NASA declared Elroy a complete success. Over four billion measurements were used by Elroy to complete a topographical map of the entire Moon. Elroy’s instruments determined that the coldest spot in our entire solar system is right smack on the Moon. It is found inside the shadows of Hermite crater which is located near the north pole. It is a bitter minus 415 degrees Fahrenheit. The gringa hopes Elroy was wearing his mittens.

Elroy is not just taking photos and temperature readings. The rover is also looking for water deposits, such as ice, and searching for fuel resources such as hydrogen. In preparation for future manned Moon missions, environmental radiation levels are also recorded.

So, the next time you gaze up at the Moon, give Elroy a salute. He is still on the job!

 

Sources: www.nasa.gov, www.moonconnection.com

 

Image Source: http://www.nasa.gov