  Starting in December 2014, Kepler K2 observed Neptune continuously for 49
days at a 1-minute cadence. The goals consisted of studying its atmospheric
dynamics (Simon et al. 2016), detecting its global acoustic oscillations (Rowe
et al., submitted), and those of the Sun, which we report on here. We present
the first indirect detection of solar oscillations in intensity measurements.
Beyond the remarkable technical performance, it indicates how Kepler would see
a star like the Sun. The result from the global asteroseismic approach, which
consists of measuring the oscillation frequency at maximum amplitude "nu_max"
and the mean frequency separation between mode overtones "Delta nu", is
surprising as the nu_max measured from Neptune photometry is larger than the
accepted value. Compared to the usual reference nu_max_sun = 3100 muHz, the
asteroseismic scaling relations therefore make the solar mass and radius appear
larger by 13.8 +/- 5.8 % and 4.3 +/- 1.9 % respectively. The higher nu_max is
caused by a combination of the value of nu_max_sun, being larger at the time of
observations than the usual reference from SOHO/VIRGO/SPM data (3160 +/- 10
muHz), and the noise level of the K2 time series, being ten times larger than
VIRGO's. The peak-bagging method provides more consistent results: despite a
low signal-to-noise ratio (SNR), we model ten overtones for degrees l=0,1,2. We
compare the K2 data with simultaneous SOHO/VIRGO/SPM photometry and BiSON
velocity measurements. The individual frequencies, widths, and amplitudes
mostly match those from VIRGO and BiSON within 1 sigma, except for the few
peaks with lowest SNR.
