Celestial Nav - really important question!

[Rob_Webb]

This question is really important cos I've got a drink riding on it this evening! /forums/images/graemlins/smile.gif

Q: Today, at what lattitude north of the equator would you need to be for the zenith of the sun to pass directly overhead? (The point being I spose that today is longest/shortest day depending on whether you are in N or S hemisphere).

I had always thought that if you were on the equator then the sun passed directly overhead at midday every day. But maybe not. Is it the tropic of Cancer?

Cheers.

 

[BrendanS]

Yes, Tropic of Cancer

The North Pole is tilted 23.45° toward the Sun, so at this time of year Zenith is at ToC, 6 months later, Zenith would be Tropic of Capricorn

So today at equator, sun would rise at roughly 23.5° N of due E, rise to 66.5° due North, then sets at 23.5° N of due West

 

[BrendanS]

Heard today you've had a few problems with mice and men on North Island. Mouse (or rat) ate fibre optic cable on one side of Island, workman with shovel took out other side of Island at same time, taking down mobiles, internet etc etc?

 

[Rob_Webb]

Yeah, on Monday most email/internet and electronic card payment systems collpased when both of Telecom's lines went down (primary and backup). They claim it was a freak co-incidence with one being broken by workmen and the backup being gnawed through by rats (where it crosses a railway bridge) at around the same time, believe it or not??!! /forums/images/graemlins/shocked.gif

 

[Rob_Webb]

Just found out via another source that the answer is indeed TOC with exact lattitude of 23 deg 26 min 22 sec.

Cheers!

 

[landaftaf]

[ QUOTE ]
Yes, Tropic of Cancer

The North Pole is tilted 23.45° toward the Sun, so at this time of year Zenith is at ToC, 6 months later, Zenith would be Tropic of Capricorn

So today at equator, sun would rise at roughly 23.5° N of due E, rise to 66.5° due North, then sets at 23.5° N of due West

[/ QUOTE ]

the sun will remain at the same declination all day, so it rises at 23 26, be at 23 26 at noon and set at 23 26

see table

http://www.wsanford.com/~wsanford/exo/sundials/DEC_Sun.html

suns declination being an imaginary line on the celestial sphere tracing out the path of the sun
or to put it more succinctly
http://en.wikipedia.org/wiki/Declination#Sun

hope this wins you your pint

/forums/images/graemlins/cool.gif

 

[Rob_Webb]

Thank you, I'm sure it will. I'll let you know how it tastes!

Cheers.

 

[Rob_Webb]

Thank you, I'm sure it will. I'll let you know how it tastes!

Cheers.

 

[Rob_Webb]

Thank you, I'm sure it will. I'll let you know how it tastes!

Cheers.