Heart murmur. Heart murmurs are heart sounds produced when blood flows across one of the heart valves that are loud enough to be heard with a stethoscope. There are two types of murmurs. A functional murmur or physiologic murmur is a heart murmur that is primarily due to physiologic conditions outside the heart. Other types of murmurs are due to structural defects in the heart itself.
Voyager 2 passed Neptune in the summer of 1989, the first spacecraft to observe that planet. Passing about 3,000 miles above Neptune's north pole, Voyager 2 made its closest approach to any planet since it left Earth 12 years earlier.
For other uses, see Voyager 1 (disambiguation). Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 launched 16 days after its twin, Voyager 2. Having operated for 39 years, 7 months and 10 days, the spacecraft still communicates with the Deep Space Network to receive routine commands and return data.