fter an ingenious a St  a o do so. Leavitt  tory asa computer, as ters spent tudying pograpes ofstars and making computations— tle more t it  to real astronomy at tymucem, ain unexpectedbenefits: it meant t  minds available ed to  tracted little reflective attention, and it ensured t ion of tructure of t often eluded terparts.

    One er, Annie Jump Cannon, used itive acquaintance ars to devise a system of stellar classifications so practical t it is still in use today.

    Leavitt’s contribution  a type of star knoellation Cep first ified) pulsated ellar beat. Cepe rare, but at least one of to most of us. Polaris, tar, is a Cepheid.

    e no Cepars t  tronomers, and become redgiants. try of red giants is a little ion for ties of singly ionized oms, among quite a lot else), but putsimply it means t t produces a very rening and dimming. Leavitt’s genius o realize t by comparing tive magnitudes of Cep different points in t o eacandard candles”—a term sill in universal use. tive distances, not absolute distances,but even so it  time t anyone o measure thelarge-scale universe.

    (Just to put ts into perspective, it is pering t at time Leavittand Cannon al properties of tograpes, tronomer illiam o a first-class telescope as often as ed, cing insects.)Combining Leavitt’s cosmic yardstick o Slips, Eded points in space  a puffof distant gossamer in tellation kno a gas cloud at allbut a blaze of stars, a galaxy in its oleast nine -years aer—vastly vaster—tin for “clouds,