How do you figure out what constellation of the zodiac the sun is said to be crossing

[Cyrus80772]

How do you figure out what constellation of the zodiac the sun is said to be crossing during certain months?

 

[russ_watters]

The sun and stars roughly rotate together, so the sun is literally in that constellation for about a month - all day, every day.

 

[marcus]

... the constellation in a strait line if you do it at true midnight right? Like if the constellation was Leo you could say the sun is crossing Leo? Is that how you do it?

What Zodiac constellation is 180 degrees (or six months) different from Leo?

If Leo is overhead or more accurately on the meridian at midnight, then it is the midnight meridian (not the sun) that is "in Leo" or in the Leo direction.
The sun is in the opposite direction. Whatever the 180 degrees opposite to Leo is.

 

[Cyrus80772]

So what meathod would I use to verify what constillation the sun is currently in?

 

[russ_watters]

So what meathod would I use to verify what constillation the sun is currently in?

What exactly do you mean by "verify"? You can use wikipedia or a star chart and they'll tell you.

 

[yenchin]

As a passing remark, of course whichever zodiac constellation the Sun is currently in will be off as compared to what *astrology* chart tells you.

 

[Redbelly98]

So what meathod would I use to verify what constillation the sun is currently in?

If you mean verify by yourself, with your own observation, then you could wait and see which constellation is 180 degrees from the sun 6 months from now.

 

[Integral]

It is easy. First learn to identify the constellations. Now observe the constellation of the zodiac on the western horizon which is first visible in the evening after the sun sets, do same in the morning for the eastern horizon. The constellation which falls between those two is the one blocked by the sun.

If you have interest in such things, you should be spending time outside at night observing the night sky. A telescope is not needed just use your eyes and a star chart.

 

[Cyrus80772]

If you mean verify by yourself, with your own observation, then you could wait and see which constellation is 180 degrees from the sun 6 months from now.

Ok so after I wait 6 months how would I "see" what constellation is 180 degrees from the sun?

 

[Cyrus80772]

It is easy. First learn to identify the constellations. Now observe the constellation of the zodiac on the western horizon which is first visible in the evening after the sun sets, do same in the morning for the eastern horizon. The constellation which falls between those two is the one blocked by the sun.

.

I did that and got aries and taurus I drew I line between them on my star map and got dead center between aries and taurus. But it was really almost dead center of aries. I am using a stellarium program so I can see exactly what sign the sun is in.

This meathod looks like a good way to get a ruff estimate of where the sun is but are there any other ways to find out more exactly when the sun will be in exactly in the center of taurus?

Further more what is the exact center of taurus? Do astrologers that account for presession
and astronomers agree on a general "center point" or exact "boundrys" every 30 degrees around the ecliptic?

 

[russ_watters]

Ok so after I wait 6 months how would I "see" what constellation is 180 degrees from the sun?

I'm not sure what you mean - you look at it with your eyes. You mean how to find it? You look exactly opposite to where the sun is, which you can find with a compass and a watch or look due south at midnight.

But again, if you have a chart made, you don't have to wait. The sun moves through the sky at a predictable rate, so you can just chart the locations and figure out where the sun is going to be if you want to do it manually...

 

[russ_watters]

I did that and got aries and taurus I drew I line between them on my star map and got dead center between aries and taurus. But it was really almost dead center of aries. I am using a stellarium program so I can see exactly what sign the sun is in.

This meathod looks like a good way to get a ruff estimate of where the sun is but are there any other ways to find out more exactly when the sun will be in exactly in the center of taurus?

Your planetarium program no doubt let's you move forward or backwards in time - just scroll around by days and see where the sun moves.

Further more what is the exact center of taurus? Do astrologers that account for presession
and astronomers agree on a general "center point" or exact "boundrys" every 30 degrees around the ecliptic?

There is no exact center - there are no well defined boundaries for constellations. They are not scientific things. And scientists certainly don't pay enough attention to astrologers to agree or disagree with them on anything - assuming you could even get astrologers to agree with each other! :rofl:

Have you read the wiki on the Zodiacs yet? It has several definitions of their positions and when the sun is in which one. Ie, if you use the IAU definition, the sun is in Aries from April 18 to May 14, so the sun would be in the center halfway between those days. http://en.wikipedia.org/wiki/Zodiac

Unlike the zodiac signs in astrology, which are all thirty degrees in length, the astronomical constellations vary widely in size. The boundaries of all the constellations in the sky were set by the International Astronomical Union (IAU) in 1930. This was essentially a mapping exercise to make the work of astronomers more efficient, and the boundaries of the constellations are not therefore in any meaningful sense an 'equivalent' to the zodiac signs. Along with the twelve original constellations, the boundaries of a thirteenth constellation, Ophiuchus (the serpent bearer), were set by astronomers within the bounds of the zodiac.

 

[Cyrus80772]

You look exactly opposite to where the sun is, which you can find with a compass and a watch or look due south at midnight.

...

OK say if the sun is in the center of leo and i wait till midnight and look due south and at center of ecliptic then i shold be looking at the consillation that is opposite Leo on the zodiac wheel, aquarius. Right?

how did they do this before there were clocks, how do you know exact midnight without timing the exact length of the night, the night before. How far off are our clocks from true midnight?

 

[Integral]

Go back and read my post #8. Gee, maybe you have to do it more than once. The ancients did it every night, not just once. Keep observing, learn your constellations. And again, keep observing. Perhaps you can figure it out.

 

[russ_watters]

You weren't real specific about your constraints, Cyrus. If you want to do it the way the ancients did, Integral's method is probably the best. It eliminates the need to know what time it is.

But your first post asked "how do you..." Well I use a planetarium program.

 

[Cyrus80772]

OK say if the sun is in the center of leo and i wait till midnight and look due south and at center of ecliptic then i should be looking at the consillation that is opposite Leo on the zodiac wheel, aquarius. Right?

 

[Redbelly98]

Pretty much. You'd have to correct for the fact that the sun is not due south exactly at noon, but you could figure out when that is and then look south exactly 12 hours later.

I guess you're assuming the ecliptic is known, that wasn't clear to me earlier.

 

[Cyrus80772]

"You look exactly opposite to where the sun is, which you can find with a compass and a watch or look due south at midnight."

Dose anyone know if the guy that said this is correct?

 

[russ_watters]

Here is a free planetarium program, it would help you a lot to download it and play with it: http://www.stellarium.org/

If you really want to do this the way the ancients did, you could also watch the sun move across the sky during the day and measure its azmuth hourly, comparing it to the compass to verify how its azmuth changes with time.

 

[Count Iblis]

You can also ask the astronauts/cosmonauts on the Space Station to look out the window and look in which constellation the Sun is.

http://spaceflight.nasa.gov/station/reference/radio/

 

[Helios]

If you know the Sun's declination, you can find the ecliptic longitude ( hence the zodiac division ) by

sin d = sin ( EL ) sin ( obliquity angle or 23.439° )

You could actually make a sundial with 7 lines of declination marked off. Compute these by EL = 0°, 30°, 60°, 90°, ...

By this sundial, you could simply see where the Sun is in the zodiac!