Ancient astronomers knew of 5 planets, Mercury, Venus, Mars, Jupiter and Saturn – 6 if you count Earth. But then in 1781, William Herschel discovered an entirely new planet, boosting the number of planets to 7. Let’s learn about Herschel, his equipment, his discoveries, and his sister Caroline – an accomplished astronomer of her own.

Today’s episode of Astronomy Cast is about another famous physicist: Enrico Fermi. We’ve already taken a look at one of Fermi’s most famous ideas, the Fermi Paradox – or, where are all the aliens? But let’s meet the man behind the ideas, the namesake for the new Fermi mission.

With Christmas just around the corner, we thought we’d investigate a mystery that has puzzled historians for hundreds of years. In the bible, the birth of Jesus was announced by a bright star in the sky that led the three wise men to his birthplace. What are some possible astronomical objects that might look like such a bright star in the sky? And were there any unusual events that happened at that time?