analemmaとは 意味・読み方・使い方

語源

From Ancient Greek ἀνάλημμα (análēmma, “pedestal of a sundial”).

発音

• IPA: /ˌæn.əˈlɛm.ə/

名詞

analemma (plural analemmas or analemmata)

1. A figure-eight curve that results when the Sun's position in the sky is plotted out over the year at the same hour of mean solar time every day. [from 17th c.]
   • 1996, James B. Kaler, The Ever-Changing Sky: A Guide to the Celestial Sphere‎ (paperback), published 2002, page 169:

     People commonly encounter the equation of time in a strangely distorted figure 8, the analemma (Figure 6.5), frequently seen on terrestrial globes. The analemma is the equation of time plotted against the Sun's declination.

   • 2002, Timothy G. Feeman, Portraits of the Earth: A Mathematician Looks at Maps‎, page 108:

     The analemma also records the difference between local solar time and local mean time for each day of the year.

   • 2011, Renna Shesso, Planets for Pagans: Sacred Sites, Ancient Lore, and Magical Stargazing‎, page 58:

     The analemma's shape varies by location, but is seldom perfectly balanced. […]
     The ends of the analemma represent summer and winter, but if we expect the solstices to be exactly at the ends and the equinoxes to be at the crossing point, we'd be wrong.

派生語

• tutulemma

参考

• equation of time
• lemniscate