Sundial, calendar and Khmer temples
Solar events at Prasat Phanom Rung
and other Khmer temples
The author of this paper has since year 2000
promoted the spectacular sunrises and sunsets at Prasat Phanom Rung (see
Bangkok Post) when the rays of the sun penetrates the ancient Khmer
temple. Since then the author have conducted GPS-based field research on
Khmer temples in NE-Thailand and has functioned as a free-lance advisor
on archaeoastronomy and Khmer sites for the Provincial Office of
The Internet is a wonderful tool for sharing
information. A negative side of the Internet is that incorrect
information often is uncritically copied from un-scientific sources. My
attribution to the Phanom Rung events in 2001 will therefore be to focus
on various misunderstandings.
1. The 'miracle' of Phanom Rung
The solar events occurs annually approximately
plus/minus 14 days from the equinoxes in March and September. The dates are
very easy to calculate when knowing the orientation of the structure,
which is easy to measure.
According to Concise Oxford Dictionary (10 edition,
CD-version) the word miracle means ''1. An extraordinary and welcome
event that is not explicable by natural or scientific laws, attributed
to a divine agency. 2. An amazing product or achievement, or an
outstanding example of something''. As the events are easy to
calculate the slogan 'Miraculous Phanom Rung' must refer to the 2nd
meaning of miracle: Amazing - or wonderful.
I therefore agree with statements like ''when the sun’s
rays pass through the 15 portals of the sanctuary at the same instant,
creating a visually stunning effect'' (the
Government Public Relations Department). And disagree with the
continuation of the text:
''This phenomenon is rare and amazing, and it testifies to the superb
skills of the temple builders'', because the phenomenon
[of sunrises or sunsets aligned with the
structure of a Khmer temple] is not rare: The ancient Khmer
‘master-builders’ generally orientated their temples equally towards two
main directions: directly east, the cardinal direction guarded by Indra
and towards the north-east, the direction guarded by Isana, an
aspect of Shiva. Phanom Rung belongs to the latter group.
Only 3% of 170 measureable Khmer temples in NE-Thailand
have an orientation so that the rising sun is not aligned with the
|Prasat Phanom Wan
||Prasat Non Ku
||Prasat Kuti Rishi Ban Khok Mueang
| The doorways ''are
so perfectly aligned that the sun's rays will shine through all
... doorways of the sanctuary in a single shaft of light''.
|Eastern view from Prasat Khao Noi
|Eastern view from Prasat Khao Lon
|Equinox sunrise at Prasat Sdok Kok Thom aligned with the
Prasat Khao Noi is located
on a small mountain with a splendid view towards north-east;
unfortunately some trees are obscuring straight east, the orientation of
Prasat Khao Lon is also located on a small mountain and
also here trees are obscuring the horizon. An inscription found at
Prasat Khao Lon informs about the date when the temple was consecrated.
This date does not coincide with the date when the sun rises (and rose)
aligned with the structure of the temple.
Prasat Sra Chaeng is located on a mountain chain with a
splendid view towards east. The temple is so ruined that the eastern
doors have collapsed. Due to its isolated location I have not visited it
at equinox, when the sun rises aligned with the structure of the temple.
Prasat Sdok Kok Thom is orientated 90 degrees true east
and the sun rises aligned with the structure at equinox. The rising sun
is not visible from the sanctum. The photo above was taken from the
lowest steps of the staircase leading up to sanctum and the space so
narrow that only one photographer can observe the event. The photo below
was taken from the sanctum at sunrise at equinox.
|Eastern view from Prasat Sra Chaeng.
|Sunrise seen from the location of the
linga in Prasat Sdok Kok Thom.
|Sunrise seen from the eastern door of Prasat Khao Lon.
2. Archaeo-astronomical event:
''Astrologers have also predicted that an
extraordinary astro-archaeological phenomenon will occur at sunrise.''
Authority of Thailand): My first comment is that I am not an
astrologer. Second that a sunrise aligned with the door-ways of a Khmer
temple does not implicate that the sunrise indicates an astro-archaeological
We have no inscriptional information evidencing that the ancient Khmers
deliberately orientated these or any other temples towards the rising
sun for any religious or other purposes. Astro-archaeological research
on solar orientations focuses primarily on temples orientated towards the point of sunrise
at the equinoxes (app. 21 March and September) and the solstices (app.
21 June and December).
The dominating orientation of Khmer temples in
NE-Thailand is towards the point of sunrise at the equinoxes. These
temples are therefore - like the royal temples at Angkor - orientated 90
degrees true east. The second most important orientation is towards
north-east with a spread in orientation from 70 - 90 degrees
(Phanom Rung = 84.5 degrees). Khmer Hindu temples orientated towards the
solstices are totally lacking.
An orientation towards the rising sun could be archao-astronomically
significant if the date was chosen deliberately, as for example if the
sunrise coincides with the date, when the temple was consecrated. Two temples in E-Thailand, Prasat Sdok Kok
Thom and Prasat Khao Lon, have dated inscriptions; but the dates of
consecration do not
coincide with the days when the sun rises aligned with the door-ways of
Prasat Phanom Rung has left us no inscriptions
informing the date of consecration; but the temple is orientated so that
the time span from the sunset to the sunrise event equals app. 28 days;
which is close to one tropical lunar month on 27.2 days (the synodic
lunar month - from full moon to full moon = 29.5 days). So if the orientation of Prasat Phanom Rung
is archaeo-astronomical significant, then the event is solar-lunar,
not merely solar. For details on this tentative theory, see:
'Solar-Lunar Events at Prasat Phanom Rung' in
Mueang Boran. In Thai: สุริยัน จันทรา
และราหูที่ปราสาทพนมรุ้ง: ข้อสังเกตทางโบราณดาราศาสตร์ (วารสารเมืองโบราณ),
where my conclusions are: 1. No past
astronomical event indicates that Prasat Phanom Rung was constructed
coinciding with a celestial events (e.g. eclipse). 2. The 15 door-ways
form a 76 m. long tunnel, which can be used for calendric observations
by an observer with some knowledge in astronomy, but we do not know if
it was intended by the constructor. None of the stone inscriptions found
at Phanom Rung inform us about whether the ancient sages living at the
temple paid any attention to the various types of astronomical aspects
of the orientation of the temple.
The National Astronomical Research Institute of
Thailand (NARIT) seems similarly reluctant
to draw conclusions
about Prasat Phanom Rung, writing that this ''wonderful
phenomenon set forth a question: Is it a mere coincidence, or is it an
indigenous astronomical wisdom of the Khmer's ancestors?''. But
anyway - and without argumentation - suggests that ''the incident in the morning of April the 3rd when
the first sunshine ray of the day passed through the
15 doorways of the Phanom Rung sanctuary, a
astronomical aspect which
should entitle this
ancient historic site to become
one of the world
astronomical heritages.'' If so, then some of
the above temple could be taken into consideration as well...
pictures above are from Wat Phu in Southern
In 2010 NARIT asked the public to ''join us at Prasat Phanom Rung for the
wonderful astronomical phenomena in the early
morning of April 3rd. Witness with your own eyes the
first ray of the sun shines through
the 15 doorways of Phanom Rung.
our webcast from your bedroom
computer through our website
http://www.narit.or.th from 5:30
onwards on April 3rd. (NARIT)
NARIT will unfortunately not be present at Phanom Rung
in April 2011 and therefore not set up a webcam to
cover the sunrise.
The event attracts hundreds of tourists; but only a
limited amount will be able to watch the sun through
the narrow gates of the temple, which in previous
years have disappointed and frustrated many
visitors. The organizers should set up a camera in
the middle of the door-ways and show the event on
large monitors. This would benefit the general
public as well as scientists. The latter need data
about time of sunrise and exact path of the sun
taken over a 4-year period in order to
qualified conclusions about Prasat Phanom Rung as an
astronomical device. A 4-year period is needed
because the sun does rise at the same spot in
continuous years, but does so in a 4-years circle:
One unique feature of Prasat Phanom Rung is that is
has door-ways penetrating the temple from east to
west; normally a Khmer temple only opens towards
east. This 'tunnel' or 'tube' makes the temple
useful as a dioptra, one of mankind's oldest
Another unique feature is that the temple is located on
a small extinct volcano. And being located above the
local horizon means that the sun is visible at
Phanom Rung before for example at Prasat Mueang Tam
on the plain below. When the sun is 50% visible at
Prasat Mueang Tam - as shown on the graphics above -
the sun is 100% visible at Phanom Rung.
Controlled video recordings would be very useful to
demonstrate the time differences due to different
local horizon - and thereby in the future be capable
of calculating the exact moment of sunrise and
sunset at Phanom Rung.
And hopefully in the future take a photo of the
rising sun at the horizon as seen through the 15
door ways of Prasat Phanom Rung.
Controlled scientific observations over continuous
years (min. 5 years) are also needed as a part of a
hitherto none existing 100 % solid argumentation for
why Prasat Phanom Rung eventually has
|Sunset aligned with a tree
||Prasat Phanom Rung, 7 March 2000
||Equinox sunrise at my test-site.
02 March 2011
© Asger Mollerup