In Hindu marriage, one of the customs is to see Arundathi star. Here, husband has to show the star to his wife. Why is this custom? Some says this is to test how sharp the bride's eyes are! Well, this can be applied to groom also. Others says this is a symbolic method to describe the story of Arundathi. Whatever the reason is, typically what happens is, this custom happens in a day light. Symbolically, priest asks husband to look at the sky and the husband yells to his wife "There is Arundati star"! In day time, It is very difficult to see Venus, the brightest object in the sky after Sun and the Moon, forget about the Arundathi star. So, actually husband and wife does not see the star. I'm sure you might have come across this situation!
Well, I'm going to tell you how you can locate Arundathi star. Before I jump into that, let me explain you a bit on Arundathi and the star.
As per purana, Arundathi is wife of sage Vasishta. And Vasishta is considered to be one of the sapta rishis (The Seven Great Sages). Now, let's look at these from Astronomy.
Often people relate Pleiades to Sapta rishis. This is wrong. Pleiades is a open star cluster and in Hindu Astronomy, it is referred to as Krittika nakshatra. Sapta Rishis are identified by modern astronomers as Big Dipper. This is a pattern of seven stars which is visible throughout the year in most parts of the Northern hemisphere. Big Dipper is situated in Ursa Major constellation. One side of the Big Dipper looks like a bowl and the other side as handle.
From the handle, the second star is called Mizar. In Hindu astronomy, it is Vasishta. Now, you can guess where you can find Arundathi! Yes, a faint star visible nearer to Vasishta is Arundathi star! In modern astronomy, it is called, Alcor. It's apparent magnitude is +3.99. In Astronomy, that means, if you can see this star in a naked eye, your eye sight is really good!
Now, let me show you the picture so that you can identify this in the sky. Of course, if you cannot locate this star, this could also be because of light pollution in your city!
Image Credit: Wikimedia (Click this link if you cannot see the above image properly)
(My point of reference is Bengaluru). Go out after 10.30PM IST, face yourself to North-East direction. Observe carefully, you can see the pattern of stars similar to the one shown above. Once you have located it, check if you can see Arundathi! Of course, let me know your (eye test) result! (By posting a comment)
Note: If you are still wondering how to locate this in your city, take the help of Sky Chart. Enter the co-ordinates of your city and use the sky map!