The characteristics measured by semen analysis are only some of the factors in semen quality. One source states that 30% of men with a normal semen analysis actually have abnormal sperm function.
Wisps of dust and gas from the nebula which formed the star can also be seen. Credit: Atlas Image courtesy of 2MASS/UMass/IPAC-Caltech/NASA/NSF. Named for the first of their type observed, T Tauri stars are variable stars which show both periodic and random fluctuations in their brightnesses. They are newly-formed (< 10 million years old) low to intermediate mass stars (< 3 solar masses) with central temperatures too low for nuclear fusion to have started.
Proxima Centauri. Proxima Centauri is the closest star to the Sun and is part of the Alpha Centauri system. It's also known as Alpha Centauri C, while the others stars in the system are called Alpha Centauri A and B. It orbits with its two companions at a distance of nearly 930 billion miles.