Some time before 300 A.D. the location of the Moon was marked by ancient Hindu astronomers by noting the position of the Moon in relation to 27 constellations or nakshatras, lunar mansions. It takes the Moon 27.3 days to move completely around the sky against the background of stars. This is about two days shorter than the time from one full Moon to the next full Moon. It apparently seemed natural to make a series of twenty seven constellations of stars in the sky; thus each night the Moon would move from one constellation to the next. Because there were only 27 constellations and it took 27.3 days to make the circuit it was not a perfect match to one night for each constellation, but it was close. Every few months an adjustment was made by adding an extra nakshatra to account for the slippage. The ancient hymns collected in the Rig Veda (written between 1200 and 900 B.C) allude to the 27 houses of the Moon and thus the lunar houses probably predate the Rig Veda..

First part of map of night sky as it would appear 2000 B.C. showing the locations of the of the nakshatras (red stars in numbered groups) along with names and figures of modern constellations. From R.A. of 24 h to R.A. of 10 h. (Voyager II software was used to make the original skychart and Adobe Photoshop was used to add the nakshatras.)

Second part of map of night sky as it would appear 2000 B.C. showing the locations of the of the nakshatras (red stars in numbered groups) along with names and figures of modern constellations. From R.A. of 14 h to R.A. of 0 h. (Voyager II software was used to make the original skychart and Adobe Photoshop was used to add the nakshatras.)

The modern names of the nakshatra stars is found in The Wonder That Was India by A.L. Basham. Their names are: 1) Asvini, 2) Bharani, 3) Krttika, 4) Rohini, 5) Mrgasiras, 6) Aredra, 7) Punarvasu, 8) Pusya, 9) Aslesa, 10) Magha, 11) Purva-phalduni, 12), Uttara-phalguni,13) Hasta, 14) Citra, 15) Svati, 16) Visakha, 17) Anuradha, 18) Jyestha, 19) Mula, 20) Purvasadha, 21) Uttarasadha, 22) Sravana, 23) Dhanistha, 24) Satabhisaj, 25) Purva-bhadrapada, 26) Uttra-bhadrapada, 27) Revati, 28) Adhijit.

This page prepared by C.Hartley, Director of the Ernest B. Wright Observatory at the Department of Physics at Hartwick College in the City of Oneonta, NY. More things from C. Hartley at his home.

All text, drawings and photographs by C. Hartley, unless otherwise noted, copyright © 2001