Closer than seems reasonable sits 55 Cancri e, a rocky exoplanet pressed so near its star that daylight there is less a sky and more a blast furnace. One orbit takes less time than a workday, a tight gravitational grip keeping the same face pointed toward the star in permanent stellar noon, while the far side never sees a sunrise.
What sounds like science fiction is simply tidal locking and radiative equilibrium pushed to extremes. On the dayside, models suggest temperatures high enough to liquefy silicate rock, turning crust into a possible magma ocean that constantly reprocesses the surface. Infrared phase-curve measurements show intense thermal emission from the hemisphere facing the star, hinting at exposed molten regions rather than a thick, insulating atmosphere that could spread heat around the globe.
More intriguing than the lava is the contrast. The nightside, shielded from direct radiation, appears far cooler, with observations indicating a steep temperature gradient across the terminator. That mismatch implies limited atmospheric heat transport and supports the idea of a world split between incandescent rock and deep cold. In 55 Cancri e, astronomers see not just an exotic super-Earth, but a laboratory for understanding how close-in rocky planets lose volatiles, cycle minerals, and test the limits of planetary geology under relentless stellar flux.
