`"Earth"_"SMa" = 149,598,261 km`

1.49598261E+8

Earth's semi-major axis in its orbit around the Sun is 149598261 km.The  Earth travels in an
elliptical path around
the sun 

Earth's Orbit

Kepler's Laws show that orbiting bodies travel in elliptical paths.  An ellipse is defined by its semi-major and semi-minor axes.