Surya Siddhanta
छादको भास्करस्येन्दुर् अधःस्थो घनवद् भवेत् । भूच्छायाम् प्राङ्मुखश् चन्द्रो विशत्य् अस्य भवेद् असौ॥
The Moon being like a cloud in a lower sphere covers the Sun (in a solar eclipse); but in a lunar one the Moon moving eastward enters the Earth's shadow and (therefore) the shadow obscures her disc.
english translation
chAdako bhAskarasyendur adhaHstho ghanavad bhavet । bhUcchAyAm prAGmukhaz candro vizaty asya bhaved asau॥
hk transliteration by Sanscript