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.
Four spacecraft have flown by Saturn so far. In 1979, Pioneer 11 became the first spacecraft to fly by and study Saturn up close. Voyager 1 flew by in 1980 and Voyager 2 in 1981. These spacecraft studied many of the moons of Saturn as well. In July 2004, the Cassini spacecraft reached Saturn. It continues to send back observations of the planet, its moons, and ring system. All of these missions made many important discoveries and sent back wonderful close-up images of Saturn, its moons, and ring system. Cool Cosmos is an IPAC website.