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Archive for November, 2012

Today is the day of the Hindu festival Diwali, the festival of light. About 200m from my house is a Hindu temple, and it has been lit up for the last several days in celebration of this important Hindu festival. Here is a picture I took on Sunday evening.


The Hindu temple in Cardiff, lit up for Diwali


Like most religions, with the exception of Islam, the Hindu calendar is a luni-solar calendar, and so the date of Diwali changes. Last year (2011) it was on the 26th of October, and next year (2013) it is on the 3rd of November, but this year it is today, the 13th of November. How is the date of Diwali calculated?

Being a luni-solar calendar, this means it follows something both the Moon and the Sun are doing. Today is a new Moon. So, the question is, what is special about today’s new Moon? What recent important Solar event happened? The Autumn equinox of course, which was on the 22nd of September this year (2012). The firsrt new Moon after this year’s Autumn equinox was on the 15th of October, and today is the second new Moon after the Autumn equinox. So, Diwali always falls on the 2nd new Moon after the Autum equinox! It’s that simple……

I wish a very happy Diwali to all my Hindu friends and students (and readers) around the World.

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In November of last year (2011), I have a talk to Swansea Astronomical Society on the early history of Yerkes Observatory. I blogged about that talk here.

Last night (Thursday 8th of November) I gave a talk to the same society with the title “ George Ellery Hale : The greatest Astronomer of the 20th Century?“. The title is deliberately provocative. In the talk I attempted to show Hale‘s main achievements in his productive life. There were many, but this slide summarises the main ones :


A summary of Hale’s main achievements in his astronomical career


Here is a gallery of all the 32 slides in the talk.



My conclusion, in the last slide, is that maybe Hale wasn’t the greatest astronomer of the 20th Century, but probably the most important. Without Hale, Yerkes Observatory would never have existed, nor Mount Wilson Observatory.

Who do you think was the greatest astronomer of the 20th Century?

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