was caused by stellar activity. This possible planet received the designation 55 Cancri c. 55 Cancri e was announced in 2004. With 8.3 Earth masses, it is a large super-Earth which was originally thought to have an orbital period of 2.8 days, though it was later found that this was an alias of its true period of 0.74 of a day by observations of e transiting in 2011. This planet was the first known instance of a fourth extrasolar planet in one system, and was the shortest-period planet until the discovery of PSR J1719−1438 b. The measurements that led to the discovery of this planet also confirmed the existence of 55 Cancri c. In 2005, Jack Wisdom combined three data sets and drew two distinct conclusions: that the 2.8-day planet was an alias and that there was a Neptune-scale planet with a period near 261 days. Fischer et al. (2008) reported new observations that they said confirmed the existence of the 2.8-day planet, as first reported by McArthur et al. (2004), and a 260-day Neptune-sized planet, as first reported by Wisdom (2005). However, Dawson and Fabrycky (2010) concluded that the 2.8-day planet was indeed an alias, as suggested by Wisdom (2005), and that the correct period was 0.7365 of a day. In 2007, Fisher et al. confirmed the existence of the 260-day planet proposed in 2005 by Wisdom. This planet, 55 Cancri f, was the first occurrence of a fifth extrasolar planet in one system. With a similar mass to c, it has a 260-day orbit, towards the inner edge of 55 Cancri A's habitable zone. The planet itself is not thought to be conducive to life, but hypothetical moons in principle could maintain at least microbial life. The planet e's eccentricity is poorly defined; varying values between 0 and 0.4 does not significantly improve the fit, so an eccentricity of 0.2 was assumed. Taking interactions between the planets into account results in a near-zero orbital eccentricity. Astrometric observations with the Hubble Space Telescope measured an inclination of 53° of the outer planet d, though this result relies on the precise orbital parameters which have been substantially revised since this was published. The observed transits of e suggest an orbit normal inclined within 9° to the line-of-sight, and a possible detection of the transit of an extended atmosphere around 55 Cancri b would, if confirmed, imply that it too is