[Gazza711]

I hate debating on facebook as it always deletes my account so hoping for some good debates here.

So.....earths orbit cant be an obvious oval shape as its only 3% shorter when closest to the sun.

[Curious Squirrel]

I hate debating on facebook as it always deletes my account so hoping for some good debates here.

So.....earths orbit cant be an obvious oval shape as its only 3% shorter when closest to the sun.

Not sure what you're trying to say here. If it's not a perfect circle, it is therefore an oval, assuming a shape still roughly circular in nature. Variation in orbit would create an oval shape, not a circle shape.

[Gazza711]

I hate debating on facebook as it always deletes my account so hoping for some good debates here.

So.....earths orbit cant be an obvious oval shape as its only 3% shorter when closest to the sun.

Not sure what you're trying to say here. If it's not a perfect circle, it is therefore an oval, assuming a shape still roughly circular in nature. Variation in orbit would create an oval shape, not a circle shape.

So it looks more oval shape then? Do we feel the difference in temperature here on earth?
All diagrams available in the last 40 years show an oval, so please explain how it looks like an obvious oval yet it should be an obvious circle not a perfect circle?

[Curious Squirrel]

I hate debating on facebook as it always deletes my account so hoping for some good debates here.

So.....earths orbit cant be an obvious oval shape as its only 3% shorter when closest to the sun.

Not sure what you're trying to say here. If it's not a perfect circle, it is therefore an oval, assuming a shape still roughly circular in nature. Variation in orbit would create an oval shape, not a circle shape.

So it looks more oval shape then? Do we feel the difference in temperature here on earth?
All diagrams available in the last 40 years show an oval, so please explain how it looks like an obvious oval yet it should be an obvious circle not a perfect circle?

Most diagrams aren't at all to scale, and tend to exaggerate the oval nature of the orbit to show we're not moving in a perfect circle. I'm not sure what you mean by 'obvious circle' unless you're referring to the fact a to scale orbit would look like a circle? Which, yes that's true. But it's still not one. We don't feel the difference though. As I recall it's partly due to Earth's tilt? I'd have to look up that information if you want more conclusive stuff.

[Gazza711]

I hate debating on facebook as it always deletes my account so hoping for some good debates here.

So.....earths orbit cant be an obvious oval shape as its only 3% shorter when closest to the sun.

Not sure what you're trying to say here. If it's not a perfect circle, it is therefore an oval, assuming a shape still roughly circular in nature. Variation in orbit would create an oval shape, not a circle shape.

So it looks more oval shape then? Do we feel the difference in temperature here on earth?
All diagrams available in the last 40 years show an oval, so please explain how it looks like an obvious oval yet it should be an obvious circle not a perfect circle?

Most diagrams aren't at all to scale, and tend to exaggerate the oval nature of the orbit to show we're not moving in a perfect circle. I'm not sure what you mean by 'obvious circle' unless you're referring to the fact a to scale orbit would look like a circle? Which, yes that's true. But it's still not one. We don't feel the difference though. As I recall it's partly due to Earth's tilt? I'd have to look up that information if you want more conclusive stuff.

Oh please do look up. Shame we cant be taught the exact facts from the start. Not sure earths tilt would cause this...would it...?

[Rounder]

Perihelion (the day the earth is closest to the sun) is around January 3rd.  Aphelion (the day the earth is farthest from the sun) is around July 4th.  Distance to the sun has no measurable effect on seasonal temperature variations.  Summers in the northern hemisphere are warmer than summers in the southern hemisphere despite the earth being farther away, due to the fact that the northern hemisphere has a higher percentage of land vs water by surface area, and land is easier to heat up than the ocean.

Wikipedia article

[Curious Squirrel]

Most diagrams aren't at all to scale, and tend to exaggerate the oval nature of the orbit to show we're not moving in a perfect circle. I'm not sure what you mean by 'obvious circle' unless you're referring to the fact a to scale orbit would look like a circle? Which, yes that's true. But it's still not one. We don't feel the difference though. As I recall it's partly due to Earth's tilt? I'd have to look up that information if you want more conclusive stuff.

Oh please do look up. Shame we cant be taught the exact facts from the start. Not sure earths tilt would cause this...would it...?

Here https://physics.stackexchange.com/questions/268062/why-dont-we-feel-the-subtle-speed-change-of-earths-elliptical-orbit Is also some math on why we don't feel the neccessary change in speed that happens due to the elliptical orbit.

[mtnman]

Technically, it is an ellipse, not an oval. See here for an explanation. http://www.differencebetween.com/difference-between-ellipse-and-vs-oval/

While it is an ellipse, it is close to being a circle, only a slight ellipse. So it doesn't really drive the seasons.

There are other exhibits of objects in the solar system with extreme ellipse orbits, like Haley's comet for example.

[3DGeek]

Oh please do look up. Shame we cant be taught the exact facts from the start. Not sure earths tilt would cause this...would it...?

According to the Wikipedia page "Earth":

Aphelion   152,100,000 km (94,500,000 mi; 1.017 AU)
Perihelion   147,095,000 km (91,401,000 mi; 0.98327 AU)

So the distance from the sun varies by about plus or minus 1.7% from the average distance.   We know this because we can very carefully measure the apparent SIZE of the sun - and it's slightly bigger at Aphelion than at Perihelion.

This is VERY close to being a circle - but it's not exactly so - hence, when precision is important, we call it an "ellipse".   The term "oval" is much more vague.  All ellipses are ovals - but not all ovals are ellipses...an egg-shaped curve is also an "oval".  (The word "oval" comes from the Latin word "ovum", meaning "egg".)

Here is where people get confused:

"Perihelion" (the time when we're closest to the sun) happens on January 4th and "Aphelion" on July 4th.   These dates vary subtly over tens of thousands of years...but those dates have been correct for most of recorded history.

This is surprising for many people who live in the Northern hemisphere because we're closest to the sun in winter and furthest in summer - which is the opposite of what most people expect.  It would be amusing to hear what Flat Earthers believe about that...but they will be wrong anyway, so maybe we don't care.

Because the intensity of sunlight varies with the SQUARE of the distance, the amount of sunlight the planet as a whole gets varies by about 6.7% with a maximum in January and a minimum in July.

The reason that the entire planet doesn't get summer in January is because of axial tilt.  Because the Northern hemisphere is tilted away from the sun in winter, the days are shorter and the angle of the sun in the sky is shallower...where the reverse is true in the Southern hemisphere.   That effect easily overpowers the 6.7% difference due to closeness - and it also explains why it's summer in January south of the equator.

Here is an ellipse with a 3.4% difference between the width and the height...so this is the shape of the Earth's orbit.  You can just about tell that it's not a perfect circle - but it's hard to be sure:

[J-Man]

If you close your eyes and concentrate you can actually feel the earth spinning and moving around the sun.

[Rational]

Isn't it interesting to see the difference in the quality of responses between:

Curious Squirrel, Rounder, Mtnman and 3dGeek (Round Earth)

And

JMan (Flat Earth)

[Gazza711]

Perihelion (the day the earth is closest to the sun) is around January 3rd.  Aphelion (the day the earth is farthest from the sun) is around July 4th.  Distance to the sun has no measurable effect on seasonal temperature variations.  Summers in the northern hemisphere are warmer than summers in the southern hemisphere despite the earth being farther away, due to the fact that the northern hemisphere has a higher percentage of land vs water by surface area, and land is easier to heat up than the ocean.

Wikipedia article

I believe the temps of summer are the same in both hemispheres as per wikipedia???
South america, africa and australia are hot but same latitude in the north and its the opposite. Plus...texas via middle east via australia is the true equatorial line as they are the hottest areas.

Another thing.....if focault spins clockwise in northern hemisphere, then shouldn't the sun and moon rise in the west?

As well..an oval isnt close in resemblence to a circle by far. Egg shaped aint frog spawn shaped. Admit it....u all thought oval at first. Now it just hearsay and my education is different to all rers???

My 3% difference involved taking the smaller distance from the larger as we dont actually know the width of the orbit...do we?

I would say that the uk seasons are a month in front.

[StinkyOne]

Perihelion (the day the earth is closest to the sun) is around January 3rd.  Aphelion (the day the earth is farthest from the sun) is around July 4th.  Distance to the sun has no measurable effect on seasonal temperature variations.  Summers in the northern hemisphere are warmer than summers in the southern hemisphere despite the earth being farther away, due to the fact that the northern hemisphere has a higher percentage of land vs water by surface area, and land is easier to heat up than the ocean.

Wikipedia article

I believe the temps of summer are the same in both hemispheres as per wikipedia???
South america, africa and australia are hot but same latitude in the north and its the opposite. Plus...texas via middle east via australia is the true equatorial line as they are the hottest areas.

Another thing.....if focault spins clockwise in northern hemisphere, then shouldn't the sun and moon rise in the west?

As well..an oval isnt close in resemblence to a circle by far. Egg shaped aint frog spawn shaped. Admit it....u all thought oval at first. Now it just hearsay and my education is different to all rers???

My 3% difference involved taking the smaller distance from the larger as we dont actually know the width of the orbit...do we?

I would say that the uk seasons are a month in front.

Sigh...
Temps would be averaged over a large area, including the oceans. You can't determine overall average temps across the hemisphere by taking a few examples.

The Foucault pendulum doesn't spin. I swings back and forth. The Earth rotates beneath it.

Whether a circle is out of round by 1% or 50% doesn't matter.

You should study harder.

[CriticalThinker]

One of the tests of a Lego master is to create a sphere out of rectangular blocks.  There is bound to be a slight difference circumference in that sphere if you measured from all available points because each block would still have a point somewhere but overall you would probably call it a sphere.  In technical terms, it's not a perfect sphere.  The orbit isn't a perfect circle, but darn close.  An orbit off by 3% isn't that easy to discern by eye and would look like a perfect circle.  That's because our eyes aren't that good at spotting subtle variations.  An oval could be egg shaped as in not symmetrical in both the vertical and horizontal bisections.  An ellipse, is symmetrical in both vertical and horizontal bisections.  To the best of my recollection, earth's orbit is described as an ellipse, not an oval.

However, a lot of words tend to change their meanings over a long enough time line so take it with a grain of salt.

CT

[Rounder]

an oval isnt close in resemblence to a circle by far.

It is, if the shape is only very slightly wider on the major axis

Egg shaped aint frog spawn shaped.

What?

My 3% difference involved taking the smaller distance from the larger as we dont actually know the width of the orbit...do we?

Yes, we do.  In fact we have good orbit ephemeris for all the major bodies in the solar system (based since Kepler on elliptical heliocentric orbits), and for many of the minor bodies as well.  This allowed us to put Mariner, Voyager, Cassini, Juno, New Horizons, and many other interplanetary probes precisely where we wanted them. 

It is also an area of science with the rare opportunity for amateur observers to contribute in a meaningful way, by conducting observations that help refine the orbital ephemerides of minor solar system objects.  The technique is called "occultation" and one participates by positioning oneself in the projected shadow path created when an asteroid passes in front of (or "occults") a star. 


It doesn't even require a very large telescope to do it, here's a setup created by taking apart a pair of binoculars and attaching a webcam:



Deploy a bunch of those across the shadow path, like this:

(the bunched up dots in Oklahoma are all Scotty Degenhardt's)

...and you can refine not only the orbit but even the shape of the object.  You can see that the projected centerline of the shadow is a little too far north, because Paul Maley's location was projected to have a hit, while Karen Young's location was projected to be a miss.

Next time Hertha occults a star, her orbit should be better defined, and the shadow centerline more accurately predicted.

[Gazza711]

Stinky one. Thx.

How can the pendulum prove anything if it is not at either pole. Sure the earth is dragging it anywhere else?

Oh....btw..  i do know re theory so no basic lessons please to all!

[3DGeek]

Stinky one. Thx.

How can the pendulum prove anything if it is not at either pole. Sure the earth is dragging it anywhere else?

Oh....btw..  i do know re theory so no basic lessons please to all!

The focault pendulum is easiest to understand if you imagine it to be at the pole - but so long as it's not too close to the equator, the fact of the Earth's rotation is still enough to provide a little push to the pendulum in each swing.

The math (well, the physics actually) gets really complicated - but there are hundreds of these pendulums in museums around the world and you don't have to watch one for very long to see that the direction of the swing gradually changes over a 24 hour period.

The Flat Earth explanation is hokey in the extreme.  According to the Wiki, there are two conflicting arguments:

Rowbotham: "Summarily, the line of the pendula must be 25 meters in length to get the minimum effect, and so by necessity, Leon Focault's original experiments between latitudes were conducted outside hung from a tree exposed to the elements. Dr. Rowbotham finds that the variations of the pendula are caused entirely by the contraction and expansion of its line due to temperature variations upon the earth's surface in relation to the nearness of the Sun. These variations match up perfectly with the official published results of Focault's experiments."

...well, that's bullshit.   Focault pendulums would work at any length if you could keep them swinging for long enough - but air resistance slows them down.  So to do a practical demonstration, you need a heavy weight and a long length to overcome air resistance for long enough to make for a decent demonstration.  In a vacuum, you could make a focault pendulum well under a meter long.   Modern demonstrations are inside museums - which are generally air-conditioned buildings where there's no wind and who's temperature scarcely varies (and certainly not over the period of minutes to hours needed to show the effect clearly).

Then we have another claim (which contradicts the first one):

"Mach's Principle explains that if the earth was still and the all the stars went around the Earth then the gravitational pull of the stars would pull the pendulum. As Mach said "The universe is not twice given, with an earth at rest and an earth in motion; but only once, with its relative motions alone determinable. It is accordingly, not permitted us to say how things would be if the earth did not rotate."

Sadly (for the FE'ers) Mach's Principle has long ago been disproven.   It's not even "officially" a principle - it's a "conjecture" and it's so vaguely put together as to be unusable.  Read the Wikipedia article.

At any rate - the stars are evenly distributed around the sky, so their gravitation sums to zero in RET and to a tiny upward pull in FET.  If the Focault effect was due to gravity, then it would be overwhelmed by the (claimed) lunar gravity that the FE'ers use to explain the tides (well, one of them!).

FE cannot explain the Focault pendulum...at least not by means of either of the bogus claims on the Wiki,