Gamma Cephei Ab, or Tadmor, is the first exoplanet — outside our Solar System — to have been detected by humans. Detected is an important distinction, because while evidence of its existence dates to 1988, this was not confirmed until 2002. In the interim, other exoplanets were detected and confirmed.1
(The illustrations here are artistic impressions, not actual images of the planet.)
Physically, Gamma Cephei Ab is 9.4 times the mass of Jupiter according to the Hubble Space Telescope, so pretty massive. (Here is a scientific article, which I won’t pretend that I read or understood all of; it uses a sort of shorthand for the name: γ Cep Ab.) Its average orbital distance from its star would put it a bit farther out than Mars in our system.
Naming-notes:
- Gamma Cephei Ab, the scientific designation, refers to the binary star system of Gamma Cephei, about 45 light-years from us and found in the constellation of Cepheus. Fun fact: within a couple thousand years, Gamma Cephei will be our “North Star” in place of Polaris, due to the axial precession of Earth.2
- Tadmor, the individualized name if you will, was chosen in 2015 as part of the International Astronomical Union’s NameExoWorlds project. The winning entry was submitted from Syria and references the ancient city of the same name, also known as Palmyra.3
Any life forms on Gamma Cephei Ab/Tadmor are, as yet, undetected.
Hope it’s a good Monday out there in your part of the galaxy🪐