Planet Labs’ GeoTIFFs can be used in Google Earth, but the georeferencing metadata will only be detected by Google Earth Pro. Planet’s analytic and visual scenes load in Google Earth Pro without any issue, but there is an incompatibility in Google Earth with the EPSG:3857 spatial reference system used in Planet’s mosaic quads. Unfortunately, Google Earth is only able to recognize GeoTIFFs that have declared the EPSG:900913 in the image metadata even though EPSG:3857 and EPSG:900913 are equivalent codes.
Fortunately, there is an easy fix with GDAL:
gdalwarp -t_srs EPSG:900913 -co "COMPRESS=DEFLATE" -co "INTERLEAVE=PIXEL" mosaic.tif fixed_mosaic.tif
With EPSG:900913 in the GeoTIFF header, Google Earth will be able to correctly geolocate the image on the globe.