This episode we are joined by Darren McKee, host of The Reality Check. Darren asks about the end of the universe and Heat Death. If you have feedback or a topic suggestion, email us.

Having discussed the volcanically active moon Io on a previous episode, we ask Stuart: where else are there volcanoes in the solar system? If you have feedback or a topic suggestion, email us.

Not your typical episode! Special guest Ed Robertson talks with the crew about conspiracy theories and a recent run-in with a flat earther. Ed is the frontman of Barenaked Ladies and wrote the theme song for Big Bang Theory. If you have feedback or a topic suggestion, email us.

One of the most important numbers in Cosmology makes up this episode's question: what is the Hubble Constant? If you have feedback or a topic suggestion, email us.

NASA missions seem to often be looking for water elsewhere in the solar system. Why does NASA follow the water? If you have feedback or a topic suggestion, email us.

Occasionally rather than asking a specific question, we ask Stuart why he finds something interesting. This episode's question is: what is interesting about comets? If you have feedback or a topic suggestion, email us.

Pat asked a question last season about whether our moon improves the Earth's habitability. Stuart said it would have to wait for another episode. That time has come! If you have feedback or a topic suggestion, email us.

Many people know that Albert Einstein won a Nobel prize. But do you know why? It was for something called the photoelectric effect. Well, what's that? If you have feedback or a topic suggestion, email us.

Cristina has been waiting to ask this one since season one after pondering Kepler's laws of planetary motion. What is a gravitational assist and how does it work? If you have feedback or a topic suggestion, email us.

This episode we are joined by Darren McKee, host of The Reality Check. We previously discussed that the universe is expanding but Darren asks, "What exactly is expanding and what is it expanding into?" If you have feedback or a topic suggestion, email us.