Skip to content
Skip to main content

About this free course


Download this course

Share this free course

An introduction to exoplanets
An introduction to exoplanets

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

3.2  The Kepler-444 planetary system

In 2015, astronomers found a system of five transiting planets orbiting the star Kepler-444. Finding five new planets orbiting the same star is exciting, but what is most intriguing about this planetary system is the age of the star: it has been deduced to be 11.2 billion years old. This means Kepler-444 formed when the Universe was young. The planets orbiting this ancient star are small, similar in size to the terrestrial planets in our own Solar System. Kepler-444 probably hosts a system of five rocky planets!

An artist’s impression of the low mass star Kepler-444 and its five small transiting planets.
Figure 9  Kepler-444 and its planets

To find terrestrial-sized planets orbiting such an ancient star suggests that rocky planet formation began early in the Universe’s history. How might this be possible? Well, researchers suggest that rocky planet formation requires less chemical enrichment than previously thought, less than is needed for gas giants. Habitats similar to the early Earth may have been present in the Universe for much of its 14-billion-year history! This presents the possibility of ancient life in the Galaxy.