How can I use an image to overlay the entire earth in Google Earth?

I'm trying to overlay a map around the entire earth in Google Earth. Is there a certain dimension the image needs to be for this?

Solution

You can generate images in Google Earth by making a KML file. In a KML file there is a GroundOverlay tag that you can use to accomplish your goal like this:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <Folder>
    <name>Ground Overlays</name>
    <description>Examples of ground overlays</description>
    <GroundOverlay>
      <name>Large-scale overlay on terrain</name>
      <description>Overlay shows Mount Etna erupting 
          on July 13th, 2001.</description>
      <Icon>
        <href>http://code.google.com/apis/kml/documentation/etna.jpg</href>
      </Icon>
      <LatLonBox>
        <north>37.91904192681665</north>
        <south>37.46543388598137</south>
        <east>15.35832653742206</east>
        <west>14.60128369746704</west>
        <rotation>-0.1556640799496235</rotation>
      </LatLonBox>
    </GroundOverlay>
  </Folder>
</kml>

Here are a few links to help you understand kml files and image overlays:

KML Tutorial
KML Tutorial - Ground Overlays
Image Overlay Creator for Google Earth - Google Earth Blog