In this week's questions show, I explain why we don't know of any perfectly habitable worlds in the galaxy. Why we don't know if the Universe is finite or infinite, and why we call it "micro gravity" and not "zero gravity".

No guests this time, just a live QA with Fraser.

The Earth’s atmosphere keeps us safe from the harsh environment of space, but it also obscures our view into the cosmos. No matter how powerful a telescope you build, the turbulence of the atmosphere limits your resolution. But astronomers and engineers have an amazing technology that allows a telescope to peer into space as if the atmosphere isn’t even there, producing images from here on the ground which are as sharp and clear as if the telescope was out in space. It’s called adaptive optics, and we’re now at the point where the most powerful ground-based telescopes have matched and even exceeded the capability of space telescopes.

In this week's questions show, I wonder what would happen if SpaceX failed as a company, why New Horizons can't search for Planet 9, and I ask for your suggestions for new names to call dark matter and dark energy.

Professor Avi Loeb is one of the hardest working astrophysicists in the field, writing a blistering number of academic papers on fascinating topics like the Fermi Paradox, the habitability of other worlds, black holes, and the history of the early universe. He's also one of the people working on the Breakthrough Starshot project to send tiny probes to other star systems.

On this week's live QA, I got a chance to talk with David Brin, a science fiction author, futurist, and an advisor for NASA's Innovative Advanced Concepts awards. David and I talked about the Transparent Society, why we should go to asteroids before the Moon or Mars, and some cool ideas coming out of NIAC.

This week Professor Brad Peterson joins me to talk about the capability of the LUVOIR telescope, which is one of the next generation space telescopes NASA is considering as part of its new Decadal Survey.

In this week's QA, I explain why dark matter is really a thing, and not just some made up thing by evil astronomers. How event horizons flatten out when they spin, what kind of scientist I'd want to be, and if you could build a ladder to space.

Just me again, back from Australia answering live questions about the Universe.

Astronomers have finally solved one of the outstanding mysteries in cosmology. Forget about all the dark matter and dark energy, where’s all the missing regular mass in the Universe? This has been called the “missing baryon problem”.