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The light-day is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in oneday, and is equal to exactly 2.59020683712×1013 metres.
The ångström or angstrom (IPA: /ˈɔːŋstrəm/); Swedish: [ˈɔŋstrøm]) is a unit of length equal to 10−10 m (one ten-billionth of a metre) or 0.1 nanometre. Its symbol is Å, a letter in theSwedish alphabet.