White star above Delhi

About 700 years ago, Dilliwallahs built the Qutub Minar. The sky those days was far less polluted than it is today, so stars were much easier to spot. Those looking heavenwards then might have noticed a rather shy star of whitish hue touching the Delhi sky’s zenith every night in winter. We now know that this star nearly reaches the zenith of the national capital’s sky every day of the year — except for the fact that during summer it’s right on top during the day and invisible.

In fact, the star grazes the zenith more frequently than every ‘day’, hitting the proverbial ‘roof’ every 23 hours, 56 minutes and 4.09 seconds. It never reaches the highest point in adjoining towns like Mathura, Agra or Panipat. The star rightfully ‘belongs’ to Delhi and Delhi alone. Maybe it’s time for us to claim it as Delhi’s star.

This star is no ordinary star. It is one of the 12 brightest stars of the northern sky most easily visible in Delhi despite the thick haze that envelopes the city. It is a prominent star with a magnitude as high as 1.7. The star, popularly known by its Arabic name, El Nath — one who butts with its horns — is the second brightest star in the constellation Taurus (see image above), marking the tip of one of the celestial bull’s horns. Hindu astronomers named it Agni, while astronomers prefer calling it Beta Tauri. El Nath belongs to the B7 III category of stars. As mentioned before, it’s whitish with a tinge of blue. From its spectral reading, we know that its surface temperature is about 18,000 degrees Kelvin. (The surface temperature of the sun is much lower, about 5,700 K.)

Another remarkable thing is that the centre of our galaxy, Earth and El Nath, all lie in a straight line. So have a look at El Nath tonight when it touches the zenith of Delhi. Now in mid-February, that should happen around 8 o’clock in the evening. Sorry non-Delhiites. You’ll have to consult your star chart to spot El Nath in your town.