From Science Daily.
Jupiter and Saturn have an helium-hydrogen metallic liquid alloy in their cores. It seems this discovery arises new mysteries because if helium is fixated that way inside the giant planets it cannot be part of the explanation for their release of energy, greater than what they take from the Sun.
Milky Way's dark matter is being finally mapped - even if not yet really understood either. Scientists have found lumps and streams of the intriguing substance lurking out there just in the neighbourhood of the Solar System. Dark matter is in any case a long way from being well understood.
A dark matter density map