Python ephem library and sun's movement gives me incorrect arcseconds

Question

Using the following script, I input my correct lat/lon and I can't get the ephem library to give me the correct arcseconds for the sun which should be around 15/second.

import ephem

def calculate_sun_slowest_rate(observer):
    sun = ephem.Sun()
    observer.date = '2024/06/21 12:00:00'  # Approximate date of the summer solstice
    
    # Compute the Sun's position at the given date
    sun.compute(observer)
    
    # Initial RA and Dec
    ra_initial = sun.ra
    dec_initial = sun.dec
    
    # Advance time by one second
    observer.date = ephem.Date(observer.date + ephem.second)
    sun.compute(observer)
    
    # Final RA and Dec
    ra_final = sun.ra
    dec_final = sun.dec
    
    # Convert RA and Dec differences to degrees
    ra_diff_degrees = (ra_final - ra_initial) * 180 / ephem.pi
    dec_diff_degrees = (dec_final - dec_initial) * 180 / ephem.pi
    
    # Convert degrees to arcseconds
    ra_diff_arcseconds = ra_diff_degrees * 3600
    dec_diff_arcseconds = dec_diff_degrees * 3600
    
    return ra_diff_arcseconds, dec_diff_arcseconds

# Create an observer
observer = ephem.Observer()
observer.lat = '0'  # Latitude
observer.lon = '0'  # Longitude
observer.elevation = 0  # Elevation in meters

# Calculate the Sun's slowest rate of movement
ra_movement, dec_movement = calculate_sun_slowest_rate(observer)

print(f"Sun's RA movement per second: {ra_movement:.6f} arcseconds")
print(f"Sun's Dec movement per second: {dec_movement:.6f} arcseconds")

I always get something like:

Sun's RA movement per second: 0.042712 arcseconds
Sun's Dec movement per second: 0.007649 arcseconds

I think it's giving me the sun's movement relative to other stars, but not relative to an observer on earth which is what I want.

I was expecting it to output 15 arcseconds/second.