In stage 1, both birthrate and death rate are high, and the population grows slowly. Stage 1 describes the US for the early years of history. Then during Stage 2, improvements in health care, sanitation, and nutrition all people to live longer and reduce the death rate. The birthrate however, remains high during this stage so the population increases rapidly. This occurred in the US in the 1800s. Eventually, birthrate decreases to match the low death rate and the population growth slows and eventually stops. This is the US today.
It is about 4.22 light-years<span> from Earth and is the closest star other than the sun. Alpha Centauri A and B orbit a common center of gravity every 80 years. The average distance between them is </span>about 11 astronomical units<span> (AU) — about the same distance as the sun is to Uranus.</span>
