Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Lewis Thomson on 10/01/2022 10:03:53
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Rob would like to know the following,
"I'm intrigued in the distance of the Sun to the Earth, and, for as far long back we have recorded, I would like to see the change over the last 20 Years. Also do we have a real-time data collector of this distance?"
Leave your insights in the comments below...
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"I'm intrigued in the distance of the Sun to the Earth, and, for as far long back we have recorded, I would like to see the change over the last 20 Years.
The average distance between the earth and sun has increased approximately 300 cm.
Also do we have a real-time data collector of this distance?
Sure, you can bounce radar beams off the sun and other bodies to calculate the distance.
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The distance between the Earth and the Sun varies by about 5 million kilometers over the course of a year.
- This is because Earth's orbit is an ellipse, coming closest to the Sun in January, and farthest away in July.
- This was discovered by Kepler, and replaced the earlier idea that motions in the heavens had to be based on perfect circles (and when that didn't work, on circles rolling upon circles, only that didn't work so well, either...)
Farthest distance from the Sun (Aphelion, around 4th July every year): 152 million km (94,500,000 miles)
Closest approach to the Sun (Perihelion, around 4th January every year): 147 million km (91,401,000 miles)
The exact date varies by ±1 day due to leap years...
See: https://en.wikipedia.org/wiki/Earth
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Im the one that asked the question; and thank you for posting this Origin.
I would like to know if this distance is a big cause of Climate change.
I see from posts that the distance does change, though is there an on going change that is climbing (a distance change or orbit change), and not staying nominal?
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Im the one that asked the question; and thank you for posting this Origin.
I would like to know if this distance is a big cause of Climate change.
I see from posts that the distance does change, though is there an on going change that is climbing (a distance change or orbit change), and not staying nominal?
It can have an effect to some extent, and there are some cyclical changes in earth's orbit (see more here: https://www.fs.usda.gov/ccrc/education/climate-primer/natural-climate-cycles)
But the current (fast) changes in the climate are driven primarily by greenhouse gases (mostly carbon dioxide and methane).
We can see the effects of the cycles, as well as the recent trends (the practically vertical line at the far right) by looking at atmospheric carbon dioxide concentrations found in ice cores, the record of which goes back almost a million years (https://keelingcurve.ucsd.edu/)
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The chart at the bottom of the last post shows the natural cycles quite well. One can track the ice ages for instance. Note that the current CO2 levels are well over 400 and climbing at an unprecedented rate, pretty much at the top of the chart above that otherwise has stayed below 300 for the last million years.
There are cycles of high eccentricity to near-circular orbits. I think the moon plays a significant role in this
The primary drivers of the changing average distance of Earth is (in decreasing order of significance):
1) Solar tides, driving Earth away from the sun, energy being supplied by spin of Earth.
2) Mass of sun decreasing, also driving Earth away as solar gravity cannot maintain the orbital distance
3) Friction with meteors and such, driving the orbit lower
4) Gravitational waves, decreasing the orbital energy at the rate of about 200 watts.
1 will continue to fade until Earth becomes tide-locked with the sun, which happens long after the sun goes nova and potentially swallows the Earth.
2 will continue until the sun burns out, if Earth is still there during this lingering phase
3 Friction will decrease as free objects continue to be absorbed
4 will always be there, and will swallow all planets that survive in the long run.
None of these four have a significant short term impact on climate.
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Hi all :)
Halc you raise some interesting points.
The primary drivers of the changing average distance of Earth is (in decreasing order of significance):
1) Solar tides, driving Earth away from the sun, energy being supplied by spin of Earth.
2) Mass of sun decreasing, also driving Earth away as solar gravity cannot maintain the orbital distance
3) Friction with meteors and such, driving the orbit lower
4) Gravitational waves, decreasing the orbital energy at the rate of about 200 watts.
Could we explore them please,
1) I am assuming this refers to the delta of the suns field across the Earth, due to the inverse square law and the frictional coupling between the solid surface and the tidal bulge effectively forcing the bulge ahead of there center lines, therefore constantly pumping water up in the Sun's gravitational field.
What value of energy are you placing on this aspect from the spin of the Earth ?
2) I believe I understand this point
3) Why does the friction of meteors favour one direction ?
4) Could you expand where/how the rate of 200 Watts is derived for the Earth Sun orbital energy/distance.
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1) Solar tides, driving Earth away from the sun, energy being supplied by spin of Earth.
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I am assuming this refers to the delta of the suns field across the Earth, due to the inverse square law and the frictional coupling between the solid surface and the tidal bulge effectively forcing the bulge ahead of there center lines, therefore constantly pumping water up in the Sun's gravitational field.
What value of energy are you placing on this aspect from the spin of the Earth ?
It isn't an energy thing. The vast majority (over 99%, about 97% for lunar tides) of the energy dissipates as heat. Its the angular momentum that counts since that cannot just be radiated into space, so trick is to figure out what the torque is on Earth, and what percentage of that torque is from the sun (about 30% I think). Due to this torque, the current length of day is near 24 hours, up from probably single digits billions of years ago back when lunar tides accounted for a larger percentage of the torque.
It isn't just a water thing. Earth exerts tidal force on the moon despite it being tide locked with Earth, deforming it, which generates heat as it rocks back and forth. This energy loss is slowly translated into a less eccentric orbit. The moon's orbit is more circular than it used to be.
Similarly, the tidal forces on Earth deform the crust, generating heat in addition to that generated by water friction.
3) Why does the friction of meteors favour one direction ?
It doesn't much. Most debris in the neighborhood of Earth's orbit is part of the solar system and is likely to already have angular momentum about the sun in the same direction as everything else. But there's still randomness to it, and movement through a cloud is probably going to slow you down via friction unless the cloud is moving faster than you on average, which is unlikely for any collection of material at Earth's orbit.
4) Could you expand where/how the rate of 200 Watts is derived for the Earth Sun orbital energy/distance.
I looked it up. Wiki gravitational wave page: "the total energy of the Earth orbiting the Sun (kinetic energy + gravitational potential energy) is about 1.14×1036 joules of which only 200 watts (joules per second) is lost through gravitational radiation, leading to a decay in the orbit by about 1×10−15 meters per day or roughly the diameter of a proton."
You are free to work out that figure for yourself. I sure didn't.
The list is in order of current significance, but if it survives long enough (doesn't die when the sun expands), the order will change.
1) The planet will eventually get tide locked, and #1 goes completely away. It will slow for billions more years until the day is about 1500 hours long, then it will speed up for even longer until the day shortens once again to around 10 hours or less. Then it will slow again until finally getting tide locked. It's a long time, possibly over a trillion years. Don't wait up.
2) Long before that, the sun will cease combusting its materials at a rate faster than new material falls in. #2 will cease and then reverse.
3) The solar system might slowly get cleaned of debris, but new stuff will probably always wander by. I can't see #3 getting to zero in any reasonable time
4) Gravitational waves will never go away until the Earth falls into the sun. They'll increase as the orbital radius decreases, just like we only measure the waves from black hole mergers when they get really close.
All the planets will eventually fall into the sun barring a different calamity happen first, just as the sun and all the other stars will fall into the center of the galaxy, which of course will not happen since the alternate calamity (Andromeda eating us) will definitely happen first.
The Virgo supercluster and the Great Attractor are looking to eat all the galaxies in our local group, but we'll never reach them despite our current 600 km/sec velocity in that direction.
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Hi all :)
Ok Halc you make a lot of valid points, and as you have already stated not much to do with the original post, so I will probably start another post around the apparent change of opinion regarding energy's influence in the dynamic you were describing.
Halc : my bold
1) Solar tides, driving Earth away from the sun, energy being supplied by spin of Earth.
Changes to this in your following post,
It isn't an energy thing. The vast majority (over 99%, about 97% for lunar tides) of the energy dissipates as heat. Its the angular momentum that counts since that cannot just be radiated into space,
Given you state the energy is supplied from the earths rotation and radiates out into space, you cannot dismiss/separate the relationship between rotational momentum and rotational kinetic energy of a body.
(energy is the currency of the physical world)
http://hyperphysics.phy-astr.gsu.edu/hbase/rke.html
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Hi everyone;
No, it's not true, Earth's average distance to the Sun does not change. The distance from Earth to Sun is still the same as before.
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Hi everyone;
No, it's not true, Earth's average distance to the Sun does not change. The distance from Earth to Sun is still the same as before.
That's incorrect. Due to tidal acceleration and the loss of mass from the Sun, the average distance between the Sun and the Earth has been slowly increasing over time.
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Hi everyone;
No, it's not true, Earth's average distance to the Sun does not change. The distance from Earth to Sun is still the same as before.
That's incorrect. Due to tidal acceleration and the loss of mass from the Sun, the average distance between the Sun and the Earth has been slowly increasing over time.
I think my original question needs more Analysis, and studied more. This entire post does question a lot though, with some good theories, and exact answers.
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Hi everyone;
No, it's not true, Earth's average distance to the Sun does not change. The distance from Earth to Sun is still the same as before.
That's incorrect. Due to tidal acceleration and the loss of mass from the Sun, the average distance between the Sun and the Earth has been slowly increasing over time.
This Tidal Acceleration is very interesting, id like to know more.
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This Tidal Acceleration is very interesting, id like to know more.
It's about conservation of angular momentum.
Both sun and Earth-system have spin, and in the same general direction. This momentum must be conserved. The energy is not conserved.
So as the solar tides on Earth reduce the angular momentum of Earth's spin plus the Earth tides acting on the sun reduce the sun's spin, that angular momentum can only go one place, which is to the orbit of the pair, pushing Earth into a higher orbit.
This is much more evident in the Earth-moon system where the Earth's spin currently pushes the moon away at a rate of a meter every 26 years, compared to Earth moving away from the sun at about a meter every million years. The difference is mostly the vastly greater distance to the sun, increasing the leverage over which the fixed torque must work.
I was apparently wrong about the tides being the greatest driver of Earth's increasing orbital distance. The sun losing mass should be first, gaining us a meter of orbital distance in perhaps 20000 years.
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the delta of the suns field across the Earth, due to the inverse square law
A delta on an inverse square law for gravitation gives you an inverse cube law for tidal effects.
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HI all
sorry Evan I've not visited recently
But think the context I used was fine.
.http://hyperphysics.phy-astr.gsu.edu/hbase/tide.html#:~:text=Go%20Back-,Sun's%20Tidal%20Effect,gravity%20field%20across%20the%20Earth.
Also Halc
It isn't an energy thing. The vast majority (over 99%, about 97% for lunar tides) of the energy dissipates as heat. Its the angular momentum that counts since that cannot just be radiated into space,
Also
It's about conservation of angular momentum.
Both sun and Earth-system have spin, and in the same general direction. This momentum must be conserved. The energy is not conserved
What laws and conditions are you relying on to allow the system to lose rotational energy via radiation and not momentum via radiation to the system under consideration.
:) ;)
https://en.wikipedia.org/wiki/Gravitational_wave#Energy,_momentum,_and_angular_momentum
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What laws and conditions are you relying on to allow the system to lose rotational energy via radiation and not momentum via radiation to the system under consideration.
Basic Newtonian law, under which the Sun/Earth/Moon system is effectively closed with no external input of torque. It is obviously not closed to heat radiating away.
Spin momentum is transferred to orbital momentum until the relative spin ceases.
The link you give is for gravitational waves, which don't exist in Newtonian physics. It is a relativity thing, and it does indeed radiate away angular momentum, but at an incredibly small rate (200 watts of power, conversion to momentum left as exercise). This was listed as the 4th thing affecting Earth's orbit in my post 5, and it is driven by orbital energy, not spin energy.
The sun consuming its fuel also reduces the system angular momentum, just like getting a log spinning and then setting it on fire. Its RPM would be constant absent friction, but it would lose momentum as it loses mass to the combustion.
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Hi all
yes Halc I thought you were using more than one theory, as they disagree/conflict on some of the points you raise.
Basic Newtonian law, under which the Sun/Earth/Moon system is effectively closed with no external input of torque. It is obviously not closed to heat radiating away.
This
Water waves, sound waves, and electromagnetic waves are able to carry energy, momentum, and angular momentum and by doing so they carry those away from the source
From
https://en.wikipedia.org/wiki/Gravitational_wave#Energy,_momentum,_and_angular_momentum
yes I would agree its obviously not a closed system. and its not just gravity waves that can carry away angular momentum. :) ;)
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No distance changes happen, a proof is that no book has mentioned it. However, scientists predict it will happen after 50+ years
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, a proof is that no book has mentioned it
That's not a proof.
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, a proof is that no book has mentioned it
That's not a proof.
Err, ok, then what would be from your point?
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, a proof is that no book has mentioned it
That's not a proof.
Err, ok, then what would be from your point?
https://en.wikipedia.org/wiki/Scientific_evidence
The problem with your idea is obvious.
No book has ever mentioned the table in my cellar.
But it exists.
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table in my cellar.
Good sarcasm, but it's obvious I meant scientific books, which teach about that distance and other stuff.
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No distance changes happen, a proof is that no book has mentioned it.
Your school library must have a awfully pathetic astronomy section if not a single book mentions regular and cumulative orbital changes of Earth.
However, scientists predict it will happen after 50+ years
What, the laws of physics will suddenly change in 50 years, diverting Earth from its previously absolute constant orbital distance to a changing one?
That's can be proved wrong since no book mentions it.
Oh, you didn't mean that. You mean that scientists predict that this will be written in a book 50 years from now, and thus only then will Earth be allowed to change its distance from the sun.
how can I know why in the source I read once it was written that it is expected to be changes in 50 years or more? I've said just the info I found
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table in my cellar.
Good sarcasm, but it's obvious I meant scientific books, which teach about that distance and other stuff.
It's not sarcasm.
It's pointing out a flaw in logic.
The fact that something is not written down doesn't tell you if it's true or false.
In 1850 no scientific book said "E=MC^2"
In reality the distance from the Earth to the Sun is continuously changing, it gets longer and shorter in a cyclic way (there are other complexities but that's the big change).
It is closest to the Sun in January.
https://nationaltoday.com/perihelion-day/
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table in my cellar.
Good sarcasm, but it's obvious I meant scientific books, which teach about that distance and other stuff.
It's not sarcasm.
It's pointing out a flaw in logic.
The fact that something is not written down doesn't tell you if it's true or false.
In 1850 no scientific book said "E=MC^2"
In reality the distance from the Earth to the Sun is continuously changing, it gets longer and shorter in a cyclic way (there are other complexities but that's the big change).
It is closest to the Sun in January.
https://nationaltoday.com/perihelion-day/
Have to say your example with the formula opened my eyes, you're right, sorry for stupidity...
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You know when you`ve a good Question, when everyone's input, questions it to the last detail, and question`s everyone else`s findings.
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You know when you`ve a good Question, when everyone's input, questions it to the last detail, and question`s everyone else`s findings.
Err, what do you want to say?
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It's important to recognise that this is a joke.
https://www.pinterest.co.uk/pin/7388786872784819/