artist rendition
Artist's concept

Observations from NASA's Spitzer Space Telescope have led to the first temperature map of a super-Earth planet– a rocky planet nearly two times as big as ours. The map reveals extreme temperature swings from one side of the planet to the other, and hints that a possible reason for this is the presence of lava flows.

The toasty super-Earth 55 Cancri e (or CNC e) is relatively close to Earth at 40 light-years away. It orbits very close to its star, whipping around it every 18 hours. Because of the planet's proximity to the star, it is tidally locked by gravity just as our moon is to Earth. That means one side of 55 Cancri, referred to as the day side, is always cooking under the intense heat of its star, while the night side remains in the dark and is much cooler. The hottest side is nearly 4,400 degrees Fahrenheit (2,700 Kelvin), and the coolest is 2,060 degrees Fahrenheit (1,400 Kelvin).

The fact Spitzer found the night side to be significantly colder than the day side means heat is not being distributed around the planet very well. The data argues against the notion that a thick atmosphere and winds are moving heat around the planet as previously thought. Instead, the findings suggest a planet devoid of a massive atmosphere, and possibly hint at a lava world where the lava would become hardened on the night side and unable to transport heat.

In 2015, the public voted to give 55 Cancri e the name "Janssen," which was approved by the International Astronomical Union, after the Dutch spectacle maker credited with the invention of the microscope. The other planets in the system are also named for famous astronomers and telescope inventors of the Renaissance.

PLANET TYPE
Super-earth
DISCOVERY DATE
2004
MASS
8.08 Earth
PLANET RADIUS
1.91 x Earth
ORBITAL RADIUS
0.01544 AU
ORBITAL PERIOD
0.7 days
ECCENTRICITY
Unknown
DETECTION METHOD
Radial Velocity