Habitable zones, Lunar landers and Interstellar interlopers

The space news cycle was dominated for a while this month with the discovery of water vapour in the atmosphere of planet K2-18b. The planet is in the habitable zone of its star, but is somewhat larger than the Earth - what does that mean for its habitability? Meanwhile, radio astronomers have discovered the most massive neutron star found to date - close to the maximum theoretical limit. Closer to home, India's first attempt at landing on the Moon has ended in disaster, with the Vikram lander crashing onto the surface in the final moments of its journey. And we've had a new interstellar visitor - a comet which appears to have come from another solar system. What could we learn from the interloper as it whizzes through our neighbourhood? An extended edition of an original broadcast on 26th September 2019 as part of Pythagoras' Trousers on Radio Cardiff.