Chandra and Rohini

There’s an occultation tomorrow (Oct 2nd, 2015) – where the Moon covers the star Aldebaran ( Rohini, as known to Indians). You can consider an occultation as an eclipse where one object in the sky covers another, as seen from the earth).

The west coast of the USA slightly misses it (or slightly gets it) depending on whee you are location. Check this link for more details.http://www.skyandtelescope.com/…/moon-hides-hyades-occults…/

I used the Neave Planetarium software to get some pictures of how it would appear in the SF bay area. I suspect the accuracy particularly when showing the Moon and the star is not perfect, but you can see through the 4 pictures how the Moon hovers over the star as time goes by.

Occulations are not as rare events, but occulations of bright stars is somewhat rare, as seen from a given place. Since there are only a few bright stars near the path that Moon takes in the sky and Aldebaran (Rohini) is the brightest star that the Moon can occult

Somehow this aspect of Rohini (that it comes very close to the Moon) made an impact on ancient Indians. So when they came up with a list of the 27 lunar mansions (“Nakshatras”), they were thought as the daughters of Daksha Brahma, and wives of the Moon. And out of these 27 wives, Rohini is said to be the most favorite of all to the Moon. It is not hard to see how this imagination come through given that the Moon occults Rohini quite regularly!

-neelanjana

Where in the World is Mount Meru?

It’s been a common occurrence in Indian poetry, to compare exemplary humans Mount Meru. Even in current news reports, you may see the usage of this word to mean “great”, “of a tall order” etc.

Going back a few centuries,in a well known composition in Raga Mayamalavagoula, Tyagaraja calls Rama as Meru samana dheera, meaning Rama’s valor and majesty to that of Meru mountain. You can listen to an equally majestic rendition of the composition here by none other than Sri BMK.  In his composition in raga Lalita, Syama Shastri calls out to the divine mother Parvati as “Sumeru madhya nilaye” , one who dwells in the great mountain of Meru. Given that Parvati is the daughter of Himavan, and wife of Shiva, who dwells in Kailasa, I think it was common practice to associate Mount Meru to be somewhere in the Himalayas. By the way, you can listen to an epic rendition of nannu brovu lalita here, by LGJ. 

But where is Meru, exactly? If you believe the Wikipedia, it could be anywhere from the Himalayas to Tibet to Central Asia to Tanzania! But is it that difficult to identify it if it were so intertwined with our history?

The Mahabharata (in Bheeshma Parva)  describes Mount Meru as a globular mountain made of Gold. Surely a poetic description, but not something that would help in identifying a geographic location. The Bhagavata too has several references to Mount Meru ( 5th Skandha), but that too leaves us with poetic descriptions that tell us it is “somewhere to the north of Bharatavarha”, “surrounded by the ocean”, “golden mountain” etc.

However, no need to despair. In addition to poets such as Vyasa or Kalidasa may have had colorful descriptions, but we are lucky have had people like Aryabhata and Varahamihira, who in spite of being a little fanciful, gave descriptions that would help us identify Mount Meru,

In the Golapada section of Aryabhateeyam, Aryabhata (5th century AD) says the following:

मेरुर्योजनमात्रः प्रभाकरो हिमवता परिक्षिप्तः

नन्दनवनस्य मध्ये रत्नमयस्सर्वर्तोवृतः ||११ ||

“In the center of the Nandana forest is the bright  Mount Meru that’s a yojana in size, that is full of precious stones, and surrounded by the Himalaya Mountains” – Sure, this is as poetic as the description in the Bhagavata or Mahabharata. Not much use here.

स्वर्मॅरू स्थलमध्ये नरको वडवामुखश्च जलमध्यॅ

अमरामरा मन्यन्ते परस्परमधस्स्थितान्नियतम् || १२||

“At Meru Mountain, at the center of the landmass, live the devas; At Vadavamukha, at the center of water live the asuras. Now each of them think that the others are situated below them”

Again, not much help here – How does it matter where the devas and asuras live to identify Mount Meru? You are bound to ask me.

Thankfully, in the 16th verse in the same chapter, Aryabhata spills the beans!

देवाः पश्यन्ति भगोलार्धमुद्न्मेरु संस्थितास्सव्यं

अपसव्यगं तयार्धं दक्षिणावडवामुखे प्रेताः || १६||

“The devas situated on Mount Meru see half of the starry sphere, and the departed souls on the south end, see the other half of the starry sphere”.

Now this is a very good description of how the sky is seen from the Earth’s two poles. At each pole, only half of the starry sphere can be seen, and the halves are mutually exclusive. This implies that the Mount Meru should be located at Earth’s North pole, and Vadavamukha, at the South pole. However, it must be pointed out that that the shloka does not plainly say that Mount Meru is at the North Pole. For that, we must visit the work of Varahamihira (6th century AD).

In verse 34 of the 12th chapter ( titled भूगोलाधिकारः ), of Surya Siddhanta, a work of Varahamihira, we find the following description:

अनेकरत्न निचयो जाम्बूनदमयो गिरिः
भूगोल मध्यगो मेरुरुभयत्र विनिर्गतः

“Filled with different types of precious stones, the golden Meru mountain goes through the center of the globe onto either side”

This is as close as it gets to saying that the Mount Meru is on Earth’s axis. Note that the reference here is not to Jambu Dweepa (or India) but to “jAmbUnadamaya”.  As per the dictionary, this term means “of Jamboonada gold, or of golden etc. Narayana Pandita’s Gudharthaprakashika commentary to Surya Siddhanta also adds a shloka to show how “Jambunadamaya” implies gold. It probably refers to gold panning in river waters.

The next verse (35) goes on to say the Gods live in the top of the Meru and the demons at the bottom of the Meru. Now compare it with the description by Aryabhata that I cited earlier in this post, and you will find that they are exactly talking about the same thing! What does go through the “center of” Earth’s globe and project to both ends? It’s nothing but the earth’s axis. Underneath all the glittering gold, and being the abode of devas and asuras being spoken about in the shlokas, we see the truth plainly told – that Meru refers to nothing but the earth’s axis. The top of Meru is the North pole, and the bottom of the Meru at is the South pole.

Then in the next few verses, Varahamihira talks about 4 (fictitious, although the text doesn’t explicitly say so) cities which are separated by 90 degrees on the earth’s equator. Incidentally one of these is called “Lanka” and is in Bharatavarsha – at a distance of one fourth the circumference of the Earth, due south of Meru’s top end. This implies the Surya SiddhantaKara knew that Bharatavarsha was close to the equator. However, the “city” which he calls Lanka can’t be in India because it is due south of Ujjain and on the equator, and falls in the Indian ocean and not on land. We can only assume that he made up these “cities” to be able to describe the globe, and the movement of the globe.

And later verses tell how at the top of the Meru there is a 6 month day, which there is a six month long night at the bottom of the Meru( verse 68). In verse 72, he says as you travel towards the Meru, in either direction, the altitude of the Pole star keeps increasing – This is a very direct way of saying that Meru (or the northern end of it) is nothing but Earth’s North pole.

So where is Meru? All these references confirm that Meru meaning nothing but the Earth’s axis. Leaving aside the stuff about the imaginary cities ( even there, the astronomy of these points, are accurately described) and Gods and demons living at either end of the Meru mountain, other astronomical descriptions are quite accurate.

Why didn’t I write down all the verses here? Because, there is nothing as gratifying as finding it in the source. If you are interested to read the verses I cited, click on the the PDF file in the link below:

http://www.wilbourhall.org/pdfs/suryasiddhanth035839mbp.pdf Check page 286 for the shlokas and the commentary.

Now it should leave you with no doubt about the identity of Mount Meru!

-neelanjana

How are Stars Named?

Have you ever tried going to a dark spot, away from city lights to look at the sky from there? You’ll be amazed at the range of colors and brightness variations of stars in the night sky.  Can you guess the number of stars you can see in a very dark sky?  Do you think you can see millions of stars? No!  At the most you can see about six thousand stars in the sky. That means you probably can’t see more than three thousand stars at any given time! Strange, but true!

When you look up in a dark sky you will see stars of many different hues – bluish white, bright white, bright red, orange, yellow and several other colors in between. Some stars visible to naked eye are extremely bright, while a large number of the stars are faint. But have you wondered if these stars had any names?

Most of the bright stars in the sky, that you can see even from a light-polluted city sky have proper names. In India, many of these stars were named thousands of years ago and the same names are in vogue today. The names of twentyseven asterisms (stars, or groups of stars) starting with Ashwini, ending with Revathi which are part of the twelve constellations in the zodiac have existed for more than four thousand years. By the way, many of the stars from this list of Indian asterisms are not very bright but they were named because they helped ancient Indians to formulate their calendar based on the movement of Sun and the Moon in the background of these stars.

Apart from these, names in Indian languages are available to few other bright stars outside the zodiac as well. The pole star, called ‘Dhruva’ is probably the most well known of such stars. The word ‘Dhruva’ (ध्रुव)  in Samskrta means ‘constant’, ‘firm’ etc.  This is a very apt name because the position of this star in the sky never changes and stays constant.  The Pole star is a not an exceptionally bright star, but is a notable star because of its position it occupies in the sky. All stars in the sky appear as though they rotate around it. The Pole star never rises or sets, nor does it show any kind of movement in the sky. If you were at the North Pole, you would see the Pole star directly overhead, and all other stars go around, never rising or setting. However due to the precession of Earth’s orbit, the Pole star 4000 years ago, is not the same Pole star we have today; but tat is another discussion altogether!

                                         The Constellation of Orion

Many of the star names in English are taken from their Roman or Greek names. A large number of star names in English also come from Arabic. For those stars for which there is no native Indian name, Indian stargazers use their international (English) names.

For those stars that don’t have proper names, there is another way of nomenclature. The sky is divided into 88 constellations. Constellations are imaginary star patterns in the sky. Some constellations actually resemble what they are supposed to resemble, and for some constellations, you must have an extremely eccentric imagination to relate a constellation to the figure it is supposed to mean! But that is beside the point.  Any star you that you can see, belongs to one constellation or the other. The brightest star in a constellation is normally denoted by the Greek letter alpha, the second brightest beta, the third brightest gamma and so on. Thus, the brightest star in the constellation of Centaur would be called Alpha Centauri; the second brightest star in the constellation Leo would be called Beta Leonis. In this system, the Pole star would be called Alpha Ursa Minoris, because it is the brightest star in the constellation of Ursa Minor. Thus every star that has a proper name also has a name based on the constellation and the brightness of the star within the constellation it belongs to.

This method of naming although very useful has given some incorrect names too. For example, the bright red star Betelgeuse is called Alpha Orionis, meaning it is the brightest star in the constellation Orion. But if you look up the sky now to look at Orion, you will notice there is one more star that is brighter than Betelgeuse! That star is Rigel (or Beta Orionis, as you might have guessed). Betelgeuse is a variable star, meaning its brightness varies over time. There was a time when Betelgeuse might have actually looked brighter to bare eyes than Rigel, and that’s when this name must have come from and it has stayed on.

Using Greek letters as prefixes to stars would only work for a handful of stars in any constellation. When you look at the sky with a telescope, you’d see thousands of new stars, invisible to naked eye. A new problem of naming these arises. Astronomers have a very interesting way of dealing with this problem.

Just like the Earth is divided by imaginary lines called longitudes from North Pole to South Pole, the sky is also divided by imaginary lines going from the north pole of the sky to the South Pole. Just as there is a prime meridian on Earth (0 degree longitude), there is a 0 hours right ascension (RA) line in the sky. The line that goes through the First point of Aries (The point in sky where the Sun would be seen on the spring equinox) is called 0 hours RA. Any star in sky can be located by its co-ordinates – how many hours (and/or minutes) away from the first point of Aries and how far is it from the equator of the sky. This is very similar to locating a place on the Earth knowing the longitude and latitude.

Now you must be guessing how this helps in naming stars! Every star in a constellation is given a number by the order of right ascension. As an example, the star within the area marked for the constellation Virgo and with the least right ascension will be labeled 1 Virginis. The star with next higher right ascension will be 2 Virginis and so on. Here there is no correlation between the number and the brightness of the star.

The winter (in the northern hemisphere) are a treat to star gazers, wherever it is not cloudy or rainy!  There are a bunch of bright stars and constellations in the eastern sky. So what are you waiting for? There are many resources on the Internet to help you identify the stars and constellations. Get out and check out those bright constellations like Orion, Taurus, Gemini, Auriga and Perseus in the winter sky. You can start with the three stars from the belt of Orion, which are unmistakable (see figure). I bet you won’t miss the bright stars like Sirius, Betelgeuse, Rigel, Aldebaran and the Pleiades cluster if you head out and watch the evening sky!

-neelanjana

(This is the text of a Toastmaster’s speech I made a long time ago)

Jupiter-Moon Conjunction: January 21, 2013

Last couple months we’ve seen some nice conjunctions of Jupiter and the Moon. On January  21st, they will come closest seen from the Earth. They would be seen about half a degree apart at the closest. As a comparison, the full Moon is about half a degree in diameter.

Here is a simulated view of the conjunction.

This conjunction is well placed seen from the western hemisphere, because it happens during the early part of night for this side of the Earth. The closest point being around 7:00 pm Pacific time.  If you remember the Moon moves almost 13 degrees in one day,the conjunction may not appear so close from the eastern hemisphere  unless you wait until late in night/early morning. In any case, don’t forget to look up at the Moon on 21st January 2013

This conjunction is also a good time to observe the movement of the Moon in the background of stars on the Ecliptic. Jupiter being farther away does not move much in a few hours. But the Moon is much closer, and also there is a the advantage of a bright Jupiter close by – So if you see the Moon at an hours interval a few times in the night, you will easily be able to see how the Moon has traveled towards East  in the background of stars.

A bonus this time is the conjunction occurs in a very star-studded region of the sky – surrounded by prominent constellations such as Orion, Taurus, Auriga and Perseus. And by the way, the orange-red star close to the Moon & Jupiter is Aldebaran, also known as Alpha Tauri in sky-terminology, and is the 4th nakshatra Rohini, in the Indian lunar Zodiac.

-neelanjana

Stellarium

Here is an article about Stellarium, that appeared on today’s issue of Kannada daily Samyukta Karnataka (9/27/2012). Click on the image for a enlarged view. My article is at the bottom of the page:

If the full page view is hard to read, you may choose to click on the following  image, for a better resolution, but without the graphical elements:

(I wrote this article last year for ಅರಿವಿನ ಅಲೆಗಳು by Sanchaya).

By the way, I did not even notice another year has gone by for my blog. Surely, this has been the most inactive year for me on ಅಲ್ಲಿದೆ ನಮ್ಮ ಮನೆ!