Because BCD galaxies are metal poor and very compact, the intense ultraviolet radiation from young stars will destroy PAH molecules even if they are formed. The threshold for when these PAH molecules stop being destroyed is still uncertain.

We believe that BCD galaxies are similar to the universe's first galaxies because they are infant galaxies, actively forming stars, and are not very chemically polluted.

One of the outstanding problems in astronomy today is whether complex organic molecules of hydrogen and carbon, similar to those responsible for life on Earth, are present in the early universe.

Our goal is now to understand how certain males keep a better plumage than others. Factors like ultraviolet radiation from the sun, soiling and even feather-degrading bacteria are known to affect the color of bird feathers once they are grown, and perhaps the best males are those who spend more time preening and protecting their plumage.

There’s as many atoms in a single molecule of your DNA as there are stars in the typical galaxy. We are, each of us, a little universe.

There could be shadow galaxies, shadow stars, and even shadow people.