  We report the discovery of a two-dimensional Galaxy Manifold within the
multi-dimensional luminosity space of local galaxies. The multi-dimensional
luminosity space is constructed using 11 bands that span from far ultraviolet
to near-infrared for redshift < 0.1 galaxies observed with GALEX, SDSS, and
UKIDSS. The two latent parameters are sufficient to express 93.2% of the
variance in the galaxy sample, suggesting that this Galaxy Manifold is one of
the most efficient representations of galaxies. The transformation between the
observed luminosities and the manifold parameters as an analytic mapping is
provided. The manifold representation provides accurate (85%) morphological
classifications with a simple linear boundary, and galaxy properties can be
estimated with minimal scatter (0.12 dex and 0.04 dex for star formation rate
and stellar mass, respectively) by calibrating with the two-dimensional
manifold location. Under the assumption that the manifold expresses the
possible parameter space of galaxies, the evolution on the manifold is
considered. We find that constant and exponentially decreasing star formation
histories form almost orthogonal modes of evolution on the manifold. Through
these simple models, we understand that the two modes are closely related to
gas content, which suggests the close relationship of the manifold to gas
accretion. Without assuming a star formation history, a gas-regulated model
reproduces an exponentially declining star formation history with a timescale
of $\sim$1.2 Gyrs on the manifold. Lastly, the found manifold suggests a
paradigm where galaxies are characterized by their mass/scale and specific SFR,
which agrees with previous studies of dimensionality reduction.
