Phil and Stephen discuss mysteries both cosmic and small-scale.

The Greatest Cosmic Puzzle: Astronomers Find Stars That Appear Older Than The Universe

The oldest stars we've found in the Universe are nearly pristine, where almost 100% of what makes them up is the hydrogen and helium left over from the Big Bang. They come in at over 13 billion years old, with the oldest at 14.5 billion. And this is a big problem, because the Universe itself is only 13.8 billion years old.

Do we have the age of the universe wrong or the age of these stars wrong?

Any other possible explanation?

Tasmanian tiger: Trio release footage they claim is sighting of thylacine

Footage of a purported Tasmanian tiger sighting has been released, but the experts are yet to agree the species is back from the dead.

Key points:

Three Tasmanian men believe an animal they filmed last November is a thylacine

Wildlife expert Nick Mooney says the animal is most likely a spotted quoll

But Mr Mooney concedes there is a 20 per cent chance the animal is a Tassie tiger

The vision was recorded last November and was shown at a press conference by a group called the Booth Richardson Tiger Team (BRTT), which has been trying to track a thylacine.

The team said they had 14 cameras in an area within 50 kilometres of Maydena, changing the sites every fortnight.

What Really Happened to Russia's Lost Cosmonauts?

Examining the mysterious theories behind Russia's Lost Cosmonauts

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