Update: I tried to make it for all locations but I'm not sure if it works, so if you have the time please check it for your location (you have to edit the downloaded kml-file) and report malfunktion.
How to get your horizon:
Open the KML with a plain-text editor and change the red parts to your needs (your latitude, longitude and maybe a name), then save and open with Google sky.
Important: The string inside <href></href> should be a single line and must not contain spaces, linefeeds or carriage returns.
Code:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2" hint="target=sky">
<NetworkLink>
<name>BackyardHorizon</name>
<Style>
<ListStyle>
<listItemType>check</listItemType>
<bgColor>00ffffff</bgColor>
</ListStyle>
</Style>
<Link>
<href>http://www.k-ita.de/cgi-bin/backyardhorizon?lat=52.52,lon=13.26,name=Berlin</href>
<refreshMode>onInterval</refreshMode>
<refreshInterval>600</refreshInterval>
</Link>
</NetworkLink>
</kml>
stephanie