[5] Due to its proximity to its star, 55 Cancri e is extremely hot, with temperatures on the day side exceeding 3,000 Kelvin.

[12] In July 2014 the International Astronomical Union (IAU) launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.

[16] Like the majority of extrasolar planets found prior to the Kepler mission, 55 Cancri e was discovered by detecting variations in its star's radial velocity.

The planet's transit of its host star was announced on 27 April 2011, based on two weeks of nearly continuous photometric monitoring with the MOST space telescope.

Analysis of its transits reveal that its orbital inclination is about 83.6°,[3] and appears to be close to being aligned with the rotation of its parent star, with obliquity of 23 +14°−12°, favouring dynamically gentle inward migration scenarios for this planet.

[21] The side of the planet facing its star has temperatures more than 2,000 Kelvin (approximately 1,700 degrees Celsius or 3,100 Fahrenheit), hot enough to melt iron.

[6] It was initially unknown whether 55 Cancri e was a small gas giant like Neptune or a large rocky terrestrial planet.

Because of this disparity, the hydrogen would have to slowly diffuse out into the dayside where X-ray and ultraviolet irradiation would destroy it.

In order for this mechanism to have taken effect, it is necessary for 55 Cancri e to have become tidally locked before losing the totality of its hydrogen envelope.

[31][32] In November 2017, it was announced that infrared observations with the Spitzer Space Telescope indicated the presence of a global lava ocean obscured by an atmosphere with a pressure of about 1.4 bar, slightly thicker than that of Earth.

[33][34] In contradiction to the February 2016 findings, a spectroscopic study in 2012 failed to detect escaping hydrogen from the atmosphere,[19] and a spectroscopic study in 2020 failed to detect escaping helium, indicating that the planet probably has no primordial atmosphere.

A study published in May 2024 used observations from the James Webb Space Telescope's Near-InfraRed Camera and Mid-Infrared Instrument to produce a thermal emission spectrum of 55 Cancri e within the range of 4 to 12 μm.