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The Mysterious Meridian of Rome

by Francois Hagnere on 12/01/10 at 7:01 am

After Strasbourg and Toledo, I take you to Rome to discover another mysterious light phenomenon. Here the Sun and some stars appear at very special moments in a marvellous basilica with a long past.

Michelangelo did wonder here until 1561 adapting the church to the caldarium, tepidarium and frigidarium of Diocletian’s former thermae. The Neapolitan architect Vanvitelli continued the prestigious works in 1749. The façade he erected was destroyed at the beginning of the XIXth century.

Early in the XVIIIth century, Cassini designed a sort of sundial within San Petronio Cathedral in Bologna. Pope Clement XI eager to have a similar instrument in Rome ordered the astronomer Francesco Bianchini to build such an instrument. The basilica of Santa-Maria degli Angeli was chosen because it is mainly oriented to the South and the windows could obviously create a light phenomenon on the marble pavement. The edifice was built on the former thermae of Diocletian that is the walls were high, well set to the ground and ideal to trace a long line enabling to measure the progress of the Sun throughout the year. And in addition, for the Pope the symbolic location would mean a victory of the Christian Calendar over the Pagan one and confirm the accuracy of the Gregorian. The meridian crossing Rome is 12° 30′ E. At solar noon (12:15 and 13:15 in the Summer) the Sun casts its light on the bronze line every day of the year. For the Summer solstice when the Sun is at its highest, the ray hits the line closest to the wall and in Winter farthest from the wall . For the equinoxes, the sun ray strikes the line half-way. The meridian line is 45 m long, and turns to be very precise, for the longer it is the better for observations.

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Bianchini added a particularity. Holes in the ceiling indicate the passage of stars. Polaris, Arcturus and Sirius can be seen if you have a chance to stay at night in the edifice. The meridian line was restored in 2002 and I can assure you it is working perfectly. Santa Maria degli Angeli was the official church of the Kingdom of Italy (1870-1946) an is still today used for official national ceremonies by the Italian Republic.

Please check out also: http://trifter.com/europe/france/the-mysterious-green-flash-at-strasbourg-cathedral/

and: http://trifter.com/europe/spain/the-curious-transparent-altar-in-toledo-cathedral/

Interior of Santa Maria degli Angeli.

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The sumptuous marble and bronze meridian of Rome in Santa Maria degli Angeli.

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Deatails of the meridian with the Pope’s Coat of Arms.

http://s3.amazonaws.com/readers/2010/01/12/3236romasantamariadegliangelimeridianafotogiovannidall27orto17june2007_1.jpg

The Sun hits the meridian at solar noon.

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The ray on the right comes from the Sun and hits the bronze line at solar noon all year round. The ray on the left comes from Polaris (Ursae Minoris).

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The meridian.

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Polaris ray goes trough the slot of the cross.

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Tomb of Italian Marshall Diaz.

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Façade of santa maria degli Angeli, these are the former Thermae of Diocletian.

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Tags: Arcturus, Bianchini, Cathedral, Diocletian, Italy, light phenomenon, Meridian, Michelangelo, Polaris, Rome, Santa Maria degli Angeli, Sirius, Strasbourg, sun, thermae, Toledo

33 Comments

AlmaG

Jan 12th, 2010

Hello King of Trifter I think I’m the first to write a commet yay! ^_^

This is so amazing! There’s actually logic behind this magnificent art having 3 purpose: (1) Art, (2) It measures the progress of the sun through out the year, and (3) symbolic for the victory of the christian calendar.

You’ve done a great job in showing the true meaning of this meridian. It’s not just a piece of art but rather, it’s a very meaningful artwork. Now everyone has another reason to admire it. ^_^

AlmaG

Jan 12th, 2010

OOps! typo… It’s comment not commet -_^

giftarist

Jan 12th, 2010

Great pictures to go with a great article. Excellent!

haikumad

Jan 12th, 2010

Wow! You are an expert in this area. Did you take the pix? Wonderful.

albert1jemi

Jan 12th, 2010

great information

clay hurtubise

Jan 12th, 2010

Amazing stuff! The Mayans also had this technique down, just a pity all their books were burned by the Spaniards.
Thanks,
Clay

Starpisces

Jan 12th, 2010

really fantastic!

qasimdharamsy

Jan 12th, 2010

Nice one…thanks…

drelayaraja

Jan 12th, 2010

Nice article

Sharif Ishnin

Jan 12th, 2010

Excellent article. The pictures are amazing as well.

bailieman

Jan 12th, 2010

Excellent as always.

lillyrose

Jan 12th, 2010

It makes you wonder how they did things like that! Great article!

standingproud

Jan 12th, 2010

Romans certainly have an eye for beauty.
Nice job here Francois

Mr Ghaz

Jan 12th, 2010

Wow! That was great article. wonderful pictures here..Really enjoyed it. Thanks for sharing, cheers my friend

Ruby Hawk

Jan 13th, 2010

Thanks for all your fantastic work and pictures. I have learned a lot of interesting history from you.

tonywriter

Jan 13th, 2010

That is very beautiful and well pictured share,Thanx!

Greg Seltz

Jan 13th, 2010

Good info…some pics are bit blurry, but cool nonetheless

deep blue

Jan 13th, 2010

That was a captivating architecture and the light phenomena could leave to astound spectators. Another well crafted post, Francois.

Francois Hagnere

Jan 14th, 2010

Thank my friends. Rome is so marvellous and there is so much to visit! Very best wishes to all.

RS Wing

Jan 14th, 2010

Fascinating information and another beautiful Architectural Masterpiece. Precision, astronomical detail and artistic genius…..all the elements for a wonderous monument in history. Fine article Francois.