# Equation of time and solar noon

**URL:** <https://openplanetary.discourse.group/t/equation-of-time-and-solar-noon/342>\
**Category:** General\
**Created:** [January 4, 2021, 4:20pm UTC](https://openplanetary.discourse.group/t/equation-of-time-and-solar-noon/342 "2021-01-04T16:20:11Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![vigilancewx](https://avatars.discourse-cdn.com/v4/letter/v/ed655f/32.png) [@vigilancewx](https://openplanetary.discourse.group/u/vigilancewx)\
**Post date:** [January 4, 2021, 4:20pm UTC](https://openplanetary.discourse.group/t/equation-of-time-and-solar-noon/342/1 "2021-01-04T16:20:12Z")

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Hello

If I am not mistaken

“The equation of time is defined as the offset between mean time (my local clock) and solar time. Solar time is judged by the position of the Sun in the sky, where midday is the moment when the Sun appears highest in the sky on every day of the year”

import ephem  
import datetime  
from datetime import datetime  
import time  
ts = time.time()  
#####now = datetime.now()

date = datetime.now()

######print "Date: " + str(date)

obs=ephem.Observer()  
obs.date = ‘2021-01-04 09:15:53’  
###obs.date = date

obs.lat = ‘53.4975’

obs.lon = ‘-2.99’

sun = ephem.Sun()  
sun.compute(obs)

transit = obs.next\_transit(sun).datetime()  
transit\_sun = (‘Local noon is at {}:{}:{}’.format(transit.hour, transit.minute, transit.second))  
print (float(sun.alt))  
print (str(sun.alt))  
sun\_angle = float(sun.alt) \* 57.2957795 # Convert Radians to degrees  
print (“sun\_angle: %f” % sun\_angle, sun.alt, sun.az)  
print (sun.alt, sun.az)

print (transit\_sun)

print (transit)

t = datetime.time(transit)  
ts = t.hour \* 3600 + t.minute \* 60 + t.second  
print (ts)

######th = ‘{0:.2f}’.format(ts/3600)

#####print (th)

tdiff = ts-43200

The above python script will give me a solar noon of around 12.17. if I am correct that’s 17 minutes after the noon on my local clock  
Yet looking at the equation of time produced on web sites it is around 5 minutes not 17

> **[ESRL Global Monitoring Laboratory - Global Radiation and Aerosols](https://www.esrl.noaa.gov/gmd/grad/solcalc/)**

So I am confused

What is the difference between?  
The equation of time and solar noon

thanks for any help