1. Mahasivarathri Magha Masa Amavasya. Magha Nakshatram is Regulus in Leo. (“The twelve months were named after the stars near which full moon occurs and these are Chaitra, Vaishakha, Jyeshta, Ashaada, Sharavna, Bhadrapda, Ashwija, Kaartika, Margashira, Pushya, Maagha, Phalguna.”) Phalguna masam starts from tomorrow. That is the last month of our year. When it ends, this year called Sarvadhari will end and, on March 27th, the year called Virodhi will start.
2. The day of Ardra (Betelguese) nakshatram in Mrgasiramasam is also called Sivarathri per Ramesh Menon, I think that nowadays that day is called Ardra Darsanam. see below.
Is it that these two events occured on the same day in the past? How long ago did they occur on the same night?
(pronounced “beetle juice”) Betelgeuse (alpha Orionis) is the second-brightest star in the constellation called Orion and one of the brightest stars in the sky. It is a supergiant star, reddish in color, and over 600 million miles in diameter (almost 1,000 times bigger than the Sun but cooler than the Sun). Betelgeuse is about 14,000 times brighter than the Sun. If Betelgeuse were at the center of our Solar System, it would extend beyond the orbit of Jupiter. It is 520 light-years from Earth. It is a variable star, varying in magnitude from 0.3 to 1.2 over a period of about 7 years, averaging about 0.70. It is the only star (other than our sun) for which we have surface images.” quoted from http://www.enchantedlearning.com/subjects/astronomy/glossary/indexb.shtml
“Arudra Darsanam (Thiruvadirai)
falling on the day of Thiruvadirai star in Marghazhi (November-December), is a festival of great importance. The sweet dish offering on this day, Thiruvadirai kali, is something with which everyone is familiar. Arudra star is one of two stars that have the prefix “Thiru.” The other is Thiruvonam, favored for worship of Maha Vishnu. Thiruvadirai is favored for Shiva. Ancient texts say Arudra is the largest of the stars. Juxtaposed against it, planet earth is smaller than the point of a needle. Arudra is two-and-a-half crore times bigger than the sun. It has a diameter of 200 crore miles. And we learn from the Tamil scholar Kandasami Mudaliar that astronomers hold that if you place Arudra where the sun is, the star will extend beyond the earth and touch Sevvai (Mars). Arudra denotes a red flame. We call Shiva Semporjyoti or Golden Red Flame. It is in the form of light that the Lord performs his functions of creation, protection, destruction and concealment. Nataraja is the manifestation of the Lord as light. In the month Marghazhi, on the day when Thiruvadirai star and new moon coincide, we celebrate the ecstatic dance of Shiva. In Chidambaram in Tamil Nadu, there is a great abhishekam for the Lord on Thiruvadirai day in Marghazhi. ” quoted from : http://www.sriveeramakaliamman.com/festivals.htm