  During November 26-29, 2003 XMM-Newton observed soft (0.2-2 keV) X-ray
emission from Jupiter for 69 hours. The low-latitude X-ray disk emission of
Jupiter is observed to be almost uniform in intensity with brightness that is
consistent with a solar-photon driven process. The simultaneous lightcurves of
Jovian equatorial X-rays and solar X-rays (measured by the TIMED/SEE and GOES
satellites) show similar day-to-day variability. A large solar X-ray flare
occurring on the Jupiter-facing side of the Sun is found to have a
corresponding feature in the Jovian X-rays. These results support the
hypothesis that X-ray emission from Jovian low-latitudes are solar X-rays
scattered from the planet's upper atmosphere, and suggest that the Sun directly
controls the non-auroral X-rays from Jupiter's disk. Our study also suggests
that Jovian equatorial X-rays can be used to monitor the solar X-ray flare
activity on the hemisphere of the Sun that is invisible to space weather
satellites.
