Jonathan Swift of Caltech, California, led a team investigating Kepler-32, a planetary system 915 light years from Earth. The star at its centre is an M dwarf, a type that makes up 75% of stars in our galaxy. Analysis of the light from this star has confirmed that it has five planets circling it, leading to the conservative estimate of one planet for each of the 100 billion similar stars in our galaxy. This doesn’t include planets of other star types, nor Kepler-32-type planets that circle at a distance greater than 10 million miles.
Earth is 93 million miles from the sun, but because M dwarf stars are small and cool, one planet on the outermost orbit may have liquid water and be able to support life. The five planets range in size between 0.8 and 2.7 times that of Earth.
Whoever makes the decision about man’s first exoplanet visit will be spoilt for choice.