  Space-based photometric telescopes stirred up stellar astrophysics in the
last decade, and RR Lyrae stars have not been an exception from that either.
The long, quasi-continuous, high-precision data from MOST, CoRoT and Kepler
revealed a wealth of new insights about this well-known variable class. One of
the most surprising mysteries turned out to be the apparent omnipresence of a
common additional mode in all RRd and RRc stars. Moreover, fundamental-mode
stars seem to populate two distinct classes, one of which is characterized by
the presence of additional modes and/or modulation, and another limited to
strict single-mode pulsation. The presence of additional modes and multiple
modulations in RRab stars allowed us to construct Petersen diagrams for these
parameters: while the pulsation modes show clear structures according to period
ratios, there seems to be no relation between the modulation periods
themselves.
