Frequent, but mercifully brief lapses of memory result in my making an occasional mistake from which I hasten to retract when possible. In my earlier article on winter skies I had stated that Polaris was still the Pole Star at the time the Pyramids were built — about four to six thousand years back.

However, it was a star called Thuban in constellation Draco, or Dragon, three to six thousand years back when Egyptian civilisation ruled the roost.

About 12,000 years into the future, the north celestial pole will lie near the brilliant blue star named Deneb (or Zainab). Then again, in another 10,000 years, Thuban will be the Pole Star again. By the time Polaris has a second run it will be yet another three to four thousand years. The circle will be completed in 25,800 years.

Another strange effect of the cumulative gravity of sun and moon is the Equatorial bulge of planet Earth. The Equatorial region is bigger by 17 miles (28km) as compared to the Polar diameter. Centrifugal effect caused by gravity was greater billions of years ago when Earth was fluid and soft… hence the bulge! Gravity can no longer ‘move the mountains’, but is enough to cause tides in the planet’s lakes, seas and oceans.

Yet another item of great mystery, hence enchantment, is the sudden and naughty appearance of shooting stars in the night sky, summer or winter. They come from nowhere, play their game in a flash, and disappear just as unpredictably, leaving one wondering and admiring over nature’s gamesmanship and sense of humour. Shooting stars, as they are erroneously called, are in fact meteors leftover from the creation of Solar System, or perpetual wear and tear occurring on asteroids orbiting between Mars and Jupiter.

They may be inter-stellar (found between stars) or inter-planetary, though we never come across any inter-galactic matter. An exotic sight in the night sky, they are awfully small — the biggest may measure no bigger than a tiny pebble though ordinarily they are particles of dust and no more. They roam the skies and are drawn towards Earth as one of them approaches Earth’s gravitational field. Then, due to intense friction with earth’s atmosphere, it burns up. Rapid downward travel (descent) causes a burning streak that appears pleasing to the eye, and is even mysterious.

Meteorites are another form of visitors from space. They are not only bigger than meteors, but solid and stony or metallic. Many meteorites have been found and preserved in many parts of the earth. It is a matter of great relief that compared with meteors, meteorites are far more infrequent for they can be very destructive. Meteors, on the contrary, burn up on arrival and are reduced to cinders causing no harm at all. 25,000 meteors are estimated to fall to Earth every day. This has increased the weight of the planet (mass) significantly, perhaps slowing it down fractionally.

Yet another enchanting sight is that of an arm of the Milky Way. Stretching across the sky majestically, like a river of milk, unmindful of many constellations it imperiously encounters and overrides, the Milky Way comprises millions of small stars and inter-stellar gas and dust. It is only one of the many arms of the galaxy, sort of jutting out of the galactic nucleus with a population of billions of stars in each arm. What a sight!

Let us talk about some bright stars in our night sky. To begin with, Sirius is the brightest star in our skies. It lies just below the constellation Orion, but in fact is a star of constellation Canis Major, The Great Dog. After the sun, moon and planet Venus, it is the brightest object. No other star equals it in brightness, and perhaps beauty.

At ‘only’ 8.6 light years (l.y) away, only two stars are nearer: Sun, whose light takes only 8 1/2 minutes to reach us, and Alpha Centauri, 4.3 at a distance of 4.3 l.y. Between them, on the scale of brightness, is Canopus at 900 l.y. Arcturus is next at 36 l.y. The brilliant and blue Vega lies at 27 l.y. Capella comes at 45 l.y. Rigel is as bright but remote at 900 l.y.

The brightness of stars reveals a lot more than it does at first sight. Distance from Solar System and the star’s intrinsic, or original luminosity play a significant role. So that it cannot necessarily be the largest, even if it is the brightest star in the sky.

This is one of the mysteries of the universe. But that is not the end of our story.

The writer is a professional astronomer and a former head of PIA Planetaria. He can be reached at astronomerpreone@hotmail.com