10 –Lakes made of methane and ethane have been found on Titan, the largest moon of this 6^th planet from the sun. 

15 – Even Isaac Newton admitted to making it up as he went along in describing this force that we know only by inference.

20 – What inert gas is responsible for most of the lights on the Las Vegas Strip?

25 – (Analogy question) An eye is to a hurricane as what this is to an earthquake.