Porphyry, any igneous rock consisting of large crystals in a mass of much smaller crystals. The large and small crystals usually are of different minerals; the rock is generally named according to its major component (for example: granite porphyry). When cut and polished, porphyry has a beautiful pattern and contrast of colors. It is used for tombstones and ornamental panels.
While routinely scanning the stars, NASA scientists came across something they didn't expect to see: a vast area of space empty of stars, planets and matter.
The big bang theory is well-known, but there are many misconceptions about it. Like what? Let's start with this one: There was no bang.