1 Exoplanet names
All planets outside our own Solar System are given a name that tells you which star they belong to. The planet’s name is the star’s name with a lower-case letter added, so for instance 51 Pegasi b is the first planet found orbiting the star 51 Pegasi. If a second planet is found orbiting this star, it will be called 51 Pegasi c.
In some systems several planets are known; for example, Kepler-444 b, Kepler-444 c, Kepler-444 d, Kepler-444 e, and Kepler-444 f are the five planets orbiting the star Kepler-444. Astronomers use only lower-case letters to designate planets.
Activity 1 What’s in a name?
What can you say immediately about these planets?
- Aldebaran b
Aldebaran b is the first planet discovered orbiting the star called Aldebaran.
- HD 96700 c
HD 96700 c is the second planet discovered orbiting the star called HD 96700. This name is just a catalogue number.
- K2-19 d
K2-19 d is the third planet discovered orbiting the star called K2-19.