Where would we be without our moon?

[ScienceLord]

Rightey, first things first, Neil Armstrong wouldn't be as famous and rich as he is, and the night sky would be darker than usual. But moving on to a more serious matter, we rely on the moon for many many things, probably the best known one is how the moon affects our tide, how it uses our oceans to keep it tidally 'locked'.

 

Our days would be shorter, the tidal pull from the gravity of the moon slows us down. The Earths rotation slows down because of the moon, but only by about a second every 50,000 years or so. But this difference on the cosmic scale is very large, in terms of millions of years, our days would be considerably shorter!

 

Before leaving you guys to think and discuss this, I need to ask you to admire the moon, as it wont be here for long, every year it gets four centimeters away from us.

 

Tell me what you guys think about this!

 

~ Science Lord

 

 

[michel123456]

Yes.

I find also very coincidental that the apparent diameter of the Moon is equal to the apparent diameter of the Sun, which fact allows a total sun eclipse to occur. I don't know what that means though.

[Greg H.]

Yes.

I find also very coincidental that the apparent diameter of the Moon is equal to the apparent diameter of the Sun, which fact allows a total sun eclipse to occur. I don't know what that means though.

It means absolutely nothing. In the distant past, the apparent diameters were different, and they will be again in the future. In fact, fast forward far enough ahead and you will never see another total eclipse of the sun from the earth again.

 

According to some NASA math, the very last total solar eclipse viewable from the surface of the earth will be 560-ish million years in the future.¹

 

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1 - See http://spacemath.gsfc.nasa.gov/weekly/4Page28.pdf.

[dimreepr]

In answer to the OP we wouldn't be here, life would probably exist. but without the stabilising effect of the moon life would still be very primitive and never become complex enough for us to evolve.

Edited January 15, 2014 by dimreepr

[Janus]

Yes.

I find also very coincidental that the apparent diameter of the Moon is equal to the apparent diameter of the Sun, which fact allows a total sun eclipse to occur. I don't know what that means though.

Not exactly equal. Both the Sun's and Moon's apparent diameters change over a range. The Sun varies from 31.6'-32.7' and the Moon from 29.3'-34.1'

 

So the Moon at any time can be anywhere from 90% to 108% the apparent size of the Sun.

 

At those times when the moon is smaller than the Sun during a solar eclipse, the best we can get is an annular eclipse, where you see a ring(or annulus) of the Sun's surface peeks around the edge of the Moon.

[ScienceLord]

Well, all i can say is, admire it while you have the chance

 

~Science Lord

[Acme]

The question put forward by the title is a literary non sequitur. "We" simply can't know such a thing. As to admiring it while we can, "we" readers are in no danger of losing sight of Luna while we live. (Notwithstanding its possible destruction by impact. Even so, if humans survive such a thing we can still admire the debris.) I admire what I want ,when I want; thank you very much.

Edited January 16, 2014 by Acme

[Strange]

 

Where would we be without our moon?

 

On another planet.

[Airbrush]

I need to ask you to admire the moon, as it wont be here for long, every year it gets four centimeters away from us.

No, the Moon will be with us FOR LONG, for many Billions of years to come.

[Spyman]

No, the Moon will be with us FOR LONG, for many Billions of years to come.

Actually the Moon will never leave Earth, while it is true that the Moon recedes from Earth with almost 4 centimeters per year, it's not true that this will cause us to lose the Moon.

 

The Moon is receding due to tidal interactions with Earth and if allowed to continue undisturbed it will cause the Moon and Earth to end up in tidal locking where both the Moon and the Earth will always have the same face against each other. When this happens the Moon will stop receding from Earth.

 

However calculations suggests it will take about fifty billion more years before this happens and the Sun will become a red giant long before that, already in about 2.3 billion years from now it will be hot enough to vaporize Earth's oceans which will dramatically lessen tidal interactions.

 

Tidal evolution

The gravitational attraction that the Moon exerts on Earth is the major cause of tides in the sea; the Sun has a lesser tidal influence. If the Earth possessed a global ocean of uniform depth, the Moon would act to deform both the solid earth (by a small amount) and ocean in the shape of an ellipsoid with high points directly beneath the Moon and on the opposite side of the Earth. However, as a result of the irregular coastline and varying ocean depths, this idealization is only partially realized. While the tidal flow period is generally synchronized to the Moon's orbit around Earth, its phase can vary. In some places on Earth there is only one high tide per day, though this is somewhat rare.

 

The tidal bulges on Earth are carried ahead of the Earth-Moon axis by a small amount as a result of the Earth's rotation. This is a direct consequence of friction and the dissipation of energy as water moves over the ocean bottom and into or out of bays and estuaries. Each bulge exerts a small amount of gravitational attraction on the Moon, with the bulge on the side of the Earth closest to the Moon pulling in a direction slightly forward along the Moon's orbit, because the Earth's rotation has carried the bulge forward. The bulge on the side furthest from the Moon has the opposite effect, but the closer bulge dominates due to its comparative closer distance to the Moon. As a result, some of the Earth's angular (or rotational) momentum is gradually being transferred to the Moon's orbital momentum, and this causes the Moon to slowly recede from Earth at the rate of approximately 38 millimetres per year. In keeping with the conservation of angular momentum, the Earth's rotation is gradually slowing, and the Earth's day thus lengthens by about 23 microseconds every year (excluding glacial rebound). Both figures are valid only for the current configuration of the continents. Tidal rhythmites from 620 million years ago show that over hundreds of millions of years the Moon receded at an average rate of 22 millimetres per year and the day lengthened at an average rate of 12 microseconds per year, both about half of their current values. See tidal acceleration for a more detailed description and references.

 

The Moon is gradually receding from the Earth into a higher orbit, and calculations suggest that this would continue for about fifty billion years. By that time, the Earth and Moon would become caught up in what is called a "spin-orbit resonance" or "tidal locking" in which the Moon will circle the Earth in about 47 days (currently 27 days), and both Moon and Earth would rotate around their axes in the same time, always facing each other with the same side. (This has already happened to the Moon - the same side always faces Earth. This is slowly happening to the Earth as well.) However, the slowdown of the Earth's rotation is not occurring fast enough for the rotation to lengthen to a month before other effects change the situation: about 2.3 billion years from now, the increase of the Sun's radiation will have caused the Earth's oceans to vaporize, removing the bulk of the tidal friction and acceleration.

http://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution

Edited January 17, 2014 by Spyman

[Dekan]

Yes.

I find also very coincidental that the apparent diameter of the Moon is equal to the apparent diameter of the Sun, which fact allows a total sun eclipse to occur. I don't know what that means though.

It does seem remarkable that the period in the Earth's history when exact solar eclipses can occur, coincides with the appearance of advanced human intelligence,

 

Could there be a causal connection? It seems unlikely, given the hundreds of years that pass before a total solar eclipse can be witnessed again from any particular place on Earth. And humans, especially prehistoric ones, have short lives measured in a few decades. So no-one could have witnessed an eclipse twice. Nor, in those pre-literate times, could a witness pass on a record of an eclipse (except possibly by vague stone/bone-scratchings, which wouldn't mean much to succeeding generations).

 

So it must all be just that - coincidence....

[Danijel Gorupec]

If the reason for not having the Moon is because there was no collision with Theia, the difference could be dramatic (supposing that the impact hypothesis is correct). Earth axis tilt could be smaller, core composition could be different (including water percentage)... maybe even life would be completely different (if we suppose that there was some life before the impact)... but this is pure SF.

 

The famous JFK speech would be "We choose to go to the Mars..."

[petrushka.googol]

Think of it this way - we would have one less distortion on the space time continuum...and less iridescent nights (mostly). Our orbital path would also get shifted i guess which would cause more serious implications.

[decraig]

Without the moon, life on earth would be no more complex than bacterium applying accepted theory; the moon reduces the excursion of obliquity (axial tilt). Without the moon the axial tilt could vary as much as 80 degrees.

 

With the moon the obliquity varies from about 22 to 24 degrees over a period of 40K years.

 

However, there is some disagreement. http://io9.com/5829438/earth-doesnt-need-the-moon

Edited January 23, 2014 by decraig

[doccortex]

Did the moon ever have an internal heat source and atmosphere. If that was the case, life could have just as easily started on the moon.