Very high-energy objects and events spit out very high-energy photons, so the instrument you need in order to detect them is the X-ray telescope. <em>(C) </em>
Inconveniently, X-ray telescopes only work when they're up in orbit, because X-rays get seriously soaked up in Earth's atmosphere, and most of them never make it down to the surface ... (lucky for us !) .
False the North Star never changes it position
Electromagnetic waves do not require a medium to travel through. They can travel through empty space or matter.
