An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 1 Search : 21 cm line
21 cm line
  خط ِ ۲۱ س.م.   
xatt-e 21-sântimetr (#)

Fr.: raie 21-cm   

The → emission line of → neutral hydrogen in → interstellar clouds. It lies in the → radio spectrum at → wavelength of about 21 cm, → frequency 1420 MHz. Its existence was predicted by Hendrik van de Hulst in 1944 and discovered by Harold Ewen and Edward Purcell in 1951.

Twenty-one (21); → twenty + → one; → centimeter; → line.