Comments on: The "Astronomical Unit" May Need an Upgrade as the Sun Loses Mass

By: How to Get Six Pack Fast

How to Get Six Pack Fast — Wed, 15 Apr 2009 14:14:54 +0000

After reading through the article, I feel that I really need more info. Can you suggest some more resources please?

By: Isaac NO.

Isaac NO. — Mon, 24 Mar 2008 21:39:35 +0000

How about using the transformation speed from IR to microwave, the distance would then be measured from any fixed spot in space, and then relate to any certain spot that would be appropriate to use, such as the center of our galaxy for a directional guidance f.e.?
Then you would only have to concern yourself about if the centre would stay fixed for eternity….that shouldn`t be a big problem in the measurable future at least!

By: saito

saito — Sat, 01 Mar 2008 14:53:57 +0000

if it's true….that means this universe will be 'game over' in many years later?

By: Richard Holland

Richard Holland — Wed, 20 Feb 2008 11:49:03 +0000

Excuse me, but I need to provoke a riduculus argument: some web sites are suggesting that our planet is experiencing an orbital variance, and that the AU is actually decreasing! This could be the true cause of global warming. Our global rotational speed has decreased by 1/4 second, and our magnetic shield is growing weaker (both symptons of a changing AU). I'm wondering if anyone is trying to calculate changes in the AU. It could be important!

By: Keith Atkin

Keith Atkin — Wed, 13 Feb 2008 16:35:40 +0000

There is a very simple answer to all this terrible confusion and worry over the AU.
Get rid of it, along with the light-year, and the parsec , and replace them all with the metre and and its multiples. e.g. the gigametre and terametre are ideal for solar system distances, while the petametre, exametre, zettametre and yottametre will take us to the stars and furthest galaxies. Solved!

By: ron

ron — Mon, 11 Feb 2008 14:13:45 +0000

Is there a tolerance associated with the AU? If so, would this make the loss of mass unimportant?

By: Burzycki.org - Tech and Interesting Facts

Burzycki.org - Tech and Interesting Facts — Sun, 10 Feb 2008 03:36:01 +0000

[...] The "Astronomical Unit" May Need an Upgrade as the Sun Loses Mass February 07th, 2008 | Category: Contributors, Astronomy The Sun is constantly losing mass. Our closest star is shedding material through the solar wind, coronal mass ejections and by simply generating light. As the burning giant begins a new solar cycle, it continues to lose about 6 billion kilograms (that's approximately 16 Empire State Building's worth) of mass per second. This may seem like a lot, but when compared with the total mass of the Sun (of nearly 2Ã—1030 kilograms), this rate of mass loss is miniscule. However small the mass loss, the mass of the Sun is not constant. So, when using the Astronomical Unit (AU), problems will begin to surface in astronomical calculations as this "universal constant" is based on the mass of the Sunâ€¦ (moreâ€¦) [...]

By: pantzov

pantzov — Sat, 09 Feb 2008 09:56:13 +0000

i'll never look at the AU the same way again

By: Brack the barbarian

Brack the barbarian — Sat, 09 Feb 2008 00:23:23 +0000

Sorry to be hogging this but no-one yet has answered Ralph and Steen's point about a 'massless' object feeling the effect of the sun's gravity. The essential misunderstanding Ralph is in your reference to 'Newtonian'. In Relativity a massive object (like the sun) bends time and space around itself. All other objects, whether they have mass or not, will feel the effect of this bending. Indeed, this was one of the first predictions of Einstein's theory to be checked out and it was found, during the course of an eclipse, that light (which is massless) does indeed bend when it passes close to the sun.

By: justsomeguy

justsomeguy — Fri, 08 Feb 2008 23:03:48 +0000

Why we measure the distance from the sun to us in 'AU' instead of light seconds is merely a reflection on our stubborn vanity. Man will ever be the measure of all things.

By: Brack the barbarian

Brack the barbarian — Fri, 08 Feb 2008 21:23:03 +0000

Has the definition changed recently – seriously? The original definition of the parsec was something to the effect that 'it was the distance that which an object would have a parallax of one second of arc when viewed from a baseline of one AU.' Hence the rather odd name PARallax, SECond of arc. No mention of the speed of light. If the definition has changed then I would be grateful if someone could confirm this.

By: Edward

Edward — Fri, 08 Feb 2008 18:06:25 +0000

Kevin: While it can be calculated in terms of light-years, a parsec (PARallax of one SECond of arc) is indeed based on the AU. For more info, please see the below link http://en.wikipedia.org/wiki/Parsec

By: Kevin

Kevin — Fri, 08 Feb 2008 16:57:45 +0000

It has no affect on a parsec. That is based solely on the speed of light.

By: none

none — Fri, 08 Feb 2008 16:57:39 +0000

Mercury will lag behind it's current orbital position

It's a contraction. Really.

By: UkMan

UkMan — Fri, 08 Feb 2008 16:25:54 +0000

eileen –

not sure how you can call mercury '1.0000000000000" to 13 decimal places – then calculate the other planetary distances referenced to this with the same accuracy when no planet has a perfectly circular orbit – not even your reference planet.

By: eileen

eileen — Fri, 08 Feb 2008 14:48:32 +0000

Alan Bennett and the AU

http://www.solargeometry.com/index.htm

Other than the fact that we inhabit the Earth, is there any logical reason to base these relationships on the third planet of the system? Are we still geocentric, and backwards, in our thinking?

Take a new look at the solar system and see the incredible relationships that result when Mercury, the first planet, is used as the base measure for the other planets.

Consider the relative values for planetary distances provided by Solar Geometry when Mercury equals 1:

Planet Calculated
Value from
Solar Geometry
Mercury 1.0000000000000
Venus 1.8660254037844
Earth 2.5833057115410
Mars 3.9364580433138
Jupiter 13.4399084391945
These values produce some absolutely astonishing relationships between Earth and the other planets. Keep in mind that the following relationships are not approximations. When computed using values from the Solar Geometry calculations for each planet they produce exact mathematical equalities.

By: Dark Gnat

Dark Gnat — Fri, 08 Feb 2008 14:40:19 +0000

I agree. It's like saying an inch is "this long" in 2008, but it will be "that long" in 2108.

I think it would be best to stick with the current definition of an AU, and use it for general purposes.

It may be a good idea to decide on a real-time AU for precise measurements, but it should be given an easily identifiable name and acronym. CAU (Current AU) for example.

By: Brack the barbarian

Brack the barbarian — Fri, 08 Feb 2008 14:30:46 +0000

I can understand that no-one will lose sleep over the demise of the AU but where will that leave the parsec? The AU is an essential part of it's definition and whilst the AU may be of only local importance the parsec, kiloparsec etc most certaily is not.

By: ddk

ddk — Fri, 08 Feb 2008 10:42:56 +0000

I'm a bit confused. What is wrong with keeping something like this constant like inch, gram, etc. as long as it's origin is clearly defined? We need some stable things for reference in this world. If you need something more precise just calculate a second version and call it something like AUnow and update it at the same time as the earth day time or even dynamic calculated to the nanosecond in time.

By: Steen Jorgensen

Steen Jorgensen — Fri, 08 Feb 2008 10:19:46 +0000

Ralph, I can understand your confusion. Bear in mind, however, that a fleck of dust inside the space shuttle follows the exact same orbit around the Earth as the entire space shuttle does. For even though its mass is very small, and thus the gravitational pull from the Earth, only a very small gravitational force is required to keep it in that orbit.

The orbit of a small object (mass m) around a large object (mass M) is well-defined, as long as mÂ«M. That's why they have the word "massless" in the definition. Probably, only a swift, mathematical trick is required to show that if this holds for mâ†’0, it holds for m=0 as well.

By: David Madison, Sr.

David Madison, Sr. — Fri, 08 Feb 2008 10:12:44 +0000

For all the talk in the article, they did not give the critical number. How much mass is lost per year? It also equated two different mass loss mechanisms, one by conversion of mass into energy, and the other by solar wind and mass ejections. The energy conversion is easy enough to calculate, but how much mass does the Sun lose by expelling particles?

By: Ralph Kuhn

Ralph Kuhn — Fri, 08 Feb 2008 09:48:24 +0000

Hello,

I see another problem.

A "massless" object would not orbit the sun – even by Newtonian theory, with or without the mass of the sun changing.

Am I missing something?

Ralph

By: Alay

Alay — Fri, 08 Feb 2008 05:17:58 +0000

Yes, I Agree, the defintion of AU should change as engineering students and researchers need to keep up with the loss of mass of the sun and this also should be done in realtime, for example, the constant k should be given a dynamic status, where on could calculate the mass lost in a given period.