  For more than 140 years the chemical composition of our Sun has been
considered typical of solar-type stars. Our highly differential elemental
abundance analysis of unprecedented accuracy (~0.01 dex) of the Sun relative to
solar twins, shows that the Sun has a peculiar chemical composition with a ~20%
depletion of refractory elements relative to the volatile elements in
comparison with solar twins. The abundance differences correlate strongly with
the condensation temperatures of the elements. A similar study of solar analogs
from planet surveys shows that this peculiarity also holds in comparisons with
solar analogs known to have close-in giant planets while the majority of solar
analogs without detected giant planets show the solar abundance pattern. The
peculiarities in the solar chemical composition can be explained as signatures
of the formation of terrestrial planets like our own Earth.
