Super-Earth Exoplanet 55 Cancri e (Artist’s Concept)

 Super-Earth Exoplanet 55 Cancri e (Artist’s Concept)

This artist’s concept shows what the exoplanet 55 Cancri e could look like.

Also called Janssen, 55 Cancri e is a so-called super-Earth, a rocky planet significantly larger than Earth but smaller than Neptune, which orbits its star at a distance of only 1.4 million miles (0.015 astronomical units), completing one full orbit in less than 18 hours. (Mercury is 25 times farther from the Sun than 55 Cancri e is from its star.) The system, which also includes four large gas-giant planets, is located about 41 light-years from Earth, in the constellation Cancer.

Observations from Webb’s NIRCam and MIRI suggest that the planet may be surrounded by an atmosphere rich in carbon dioxide (CO2) or carbon monoxide (CO). Because it is so close to its star, the planet is extremely hot and is thought to be covered in molten rock. Researchers think that the gases that make up the atmosphere could have bubbled out of the magma.

An atmosphere on this planet would likely be complex and quite variable due to interactions with the magma ocean. In addition to carbon monoxide or carbon dioxide, there could be gases like nitrogen, water vapor, sulfur dioxide, some vaporized rock, and even short-lived clouds made of tiny droplets of lava condensed from the air. 

The star, 55 Cancri, is a K-type star nearly the same size and mass as the Sun, but slightly cooler and dimmer. It is just bright enough to see with the naked eye in a very dark sky. The star and planet are so close to each other that the star would appear 70 times wider in the planet’s sky than the Sun appears in our sky. In addition, because the planet is likely to be tidally locked, from any given point, the star would appear fixed in the sky.

This artist’s concept is based on new data gathered by NIRCam and MIRI as well as previous observations from other ground- and space-based telescopes, including NASA’s Hubble and retired Spitzer space telescopes. Webb has not captured any images of the planet.



NASA, ESA, CSA, Ralf Crawford (STScI)

About The Object
Object Name 55 Cancri e, also called Janssen
Object Description Super-Earth Exoplanet
R.A. Position 08h52m35.24s
Dec. Position +28d19m47.34s
Constellation Cancer
Distance 41 light-years
Dimensions Radius: 1.95 × Earth; Mass: 8.8 × Earth
About The Data
Data Description This is an artist's concept based on spectroscopic observations from a number of telescopes, including Webb, Hubble, and Spitzer. There are no direct images of 55 Cancri e.
About The Object
Object Name A name or catalog number that astronomers use to identify an astronomical object.
Object Description The type of astronomical object.
R.A. Position Right ascension – analogous to longitude – is one component of an object's position.
Dec. Position Declination – analogous to latitude – is one component of an object's position.
Constellation One of 88 recognized regions of the celestial sphere in which the object appears.
Distance The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
Dimensions The physical size of the object or the apparent angle it subtends on the sky.
About The Data
Data Description
  • Proposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
  • Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.
Instrument The science instrument used to produce the data.
Exposure Dates The date(s) that the telescope made its observations and the total exposure time.
Filters The camera filters that were used in the science observations.
About The Image
Image Credit The primary individuals and institutions responsible for the content.
Publication Date The date and time the release content became public.
Color Info A brief description of the methods used to convert telescope data into the color image being presented.
Orientation The rotation of the image on the sky with respect to the north pole of the celestial sphere.