1 December 2006

When is a Star a Sun and when is a Sun a Star?
Or
What is the difference between a Star and a Sun?

It appears that all suns are stars, but the converse is not also true.

First, a star is a celestial body (no minimum size given) that emits light produced as a result of nuclear fusion.

A star is termed a sun only if it has planets orbiting around it.

Planets are large celestial bodies that orbit a sun and do not emit light themselves (they may emit in the IR spectrum).

The IAU recently mucked up this definition when they defined a planet to be a celestial body that is "in orbit around the Sun" [emphasis added]. That makes it sound like planets can only exist in our solar system since we call our star The Sun while we refer to other stars simply as stars or suns. We also capitalize the word sun when we are talking about our star and not when speaking of other stars. So by that definition there can not be any planets outside of our solar system.

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Along the way in by quest to make sure the Sun doesn't slip into another constellation without me being aware of it I developed the this table, which compares the true astroNoMical location of the Sun during 2007 with it's astroLoGical location.

AstroNoMical Location		AstroLoGical Location
Sgr	18Dec06.0455	Sag
	22Dec	Cap
Cap	20Jan07.0009
	20Jan	Aqu
Aqr	16Feb07.1046
	20Feb	Psc
Psc	12Mar07.1217
	21Mar	Ari
Ari	19Apr07.0115
	21Apr	Tau
Tau	14May07.1249
	21May	Gem
	21Jun	Can
Gem	21Jun07.2022
Cnc	21Jul07.0109
	23Jul	Leo
Leo	11Aug07.0014
	Aug23	Vir
Vir	17Sep07.0126
	23Sep	Lib
Lib	31Oct07.1344
	23Nov	Sag
Sco	23Nov07.1659
Oph	30Nov07.0329
Sgr	18Dec07.1106
	22Dec	Cap

The table below compares the amount of time the sun is in each constellation in each of the systems.

AstroNoMy	Censtellation	AstroLoGy
25d12h	Ari	31d
38d7h	Tau	30d
29d5h	Gem	31d
20d23h	Cnc	32d
37d1h	Leo	31d
44d1h	Vir	31d
24d2h	Lib	30d
6d10h	Sco	31d
19d8h	Oph	--
43d11h	Sgr	29d
17d11h	Cap	29d
24d1h	Aqr	31d
32d7h	Psc	29d

This table shows how much the time advances each year.

Year	Date	Time	Advanced (hmm)	4-year Advance (mm)
2000	18Apr	0509
2001	18Apr	1121	612
2002	18Apr	1733	612
2003	18Apr	2340	607
2004	18Apr	0546	606	35
2005	18Apr	1158	612
2006	18Apr	1810	608
2007	19Apr	0115	705
2008	18Apr	0622	507	36
2009	18Apr	1235	613
2010	18Apr	1846	611
2011	19Apr	0051	605
2012	18Apr	0658	607	36
2013	18Apr	1311	609
2014	18Apr	1922	611
2015	19Apr	0127	605
2016	18Apr	0735	608	37
2017	18Apr	1348	613
2018	18Apr	1958	610
2019	19Apr	0203	601
2020	18Apr	0811	608	36
2021	18Apr	1425	614
2022	18Apr	2034	609
2023	19Apr	0239	605
2024	18Apr	0848	609	37
2025	18Apr	1501	613
Leap Years highlited in yellow

It looks like there might be a data point that needs correcting around 2007.

Every year the time when the sun crosses from Psc into Ari advances by about 6h9m

Max: 7.08h
Avg: 6.15h
Mean: 6.20h
Min: 5.12h

Every fourth year, beginning in 2003, the date of crossing advances from 18Apr to the morning of 19Apr. The year following that advance is a Leap Year and resets the cycle back to the morning of 18Apr.. That should have happened in 2003 also but the time of crossing missed the new day by 20 minutes. I looked at 25 years worth of dayes and this only occurred once during that timeframe. The maths for calculating the periodicity of this event are beyond me.

Looking at the difference in the time of crossing in the leap years it advances my about 36 minutes each leap year.

Max: 37 minutes
Avg: 36.16
Mean: 36 minutes
Min: 35 minutrs

At that rate of advance I calculate that the date of change will advance by one day every 40 years, and by extrapolation, using an average 30 day month, it will adbance by one month every 120 years. So in 2128 the Sun should enter Aries on about 18May. The Palm can't deal with dates beyond 2031 and my StarryNight Starter Edition only goes to 2009. It looks like Stelarium is only good to 2038 so I was having trouble checking that calculation. Night Vision bailed me out, but it says that the Sun will be in Tau on that date.

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Thunder in December presages fine weather.