Rotational work is common for the field operator, often involving eight days of 10-hour shifts followed by six days off. Unlike plant operators, field operators usually work days. Evening call-outs can occur if maintenance or production issues arise at a well site the operator covers.
Before the advent of telescopic photography, eight moons of Saturn were discovered by direct observation using optical telescopes. Saturn's largest moon, Titan, was discovered in 1655 by Christiaan Huygens using a 57-millimeter (2.2 in) objective lens on a refracting telescope of his own design. Tethys, Dione, Rhea and Iapetus (the  Sidera Lodoicea ) were discovered between 1671 and 1684 by Giovanni Domenico Cassini.
[See also: Dione: Saturn's Turned-Around Moon, Hyperion: Saturn's Spongy Moon, Mimas: Saturn's Death Star Moon, Rhea: Saturn's Dirty Snowball Moonand Tethys: Saturn's Icy Moon] Saturn's rings. Galileo Galilei was the first to see Saturn's rings in 1610, although from his telescope they resembled handles or arms. It took Dutch astronomer Christiaan Huygens, who had a more powerful telescope, to propose that Saturn had a thin, flat ring. Astronomers with even more powerful telescopes discovered that Saturn actually has many rings made of billions of particles of ice and rock, ranging in size from a grain of sugar to the size of a house. The largest ring spans up to 7,000 times the ...