The Pole Star Trivia Quiz

Answer: Ursa Minor

Ursa Minor, or the 'Little Bear', is a relatively conspicuous constellation, visible from the latitudes 90 degrees North to 10 degrees South. It is 'circum-polar', i.e. always visible in the sky, above 20 degrees North latitude.

Since the brightest stars of this constellation appear in the shape of a ladle or a saucepan, they are collectively referred to as the 'Little Dipper'. Polaris, or Alpha Ursae Minoris, is the brightest star of Ursa Minor, and is found at the tip of the 'handle' of this imaginary 'dipper'.

Answer: 1 degree

We assume that Polaris always points to the North- this, however, isn't true. It actually is about 1 degree away from the actual 'North' direction, as a result of which it appears to revolve around the Earth's axis of rotation making a circle about 2 degrees in diameter.

Of course, there are other factors which contribute to the non-steadfast nature of the Pole Star, including the precession of equinoxes, and proper motion of stars (proper motion is the apparent change in the position of a star on the celestial sphere, which is observed due to *its own* motion, rather than that of the Earth).

Answer: At the zenith (exactly overhead)

The zenith is the point exactly overhead for any observer, and depends on the observer's location- your zenith is different from mine. The Pole Star is always at the zenith for an observer on the North Pole, that is, it is exactly overhead. All the other stars appear to revolve around it- this, however is just an apparent motion, it actually is the *Earth* which is rotating around its own axis, on which the Pole Star is located.

The point exactly opposite the zenith is called the 'nadir', and as is obvious, an observer's nadir is never visible to him/her!

Answer: At a fixed point on the horizon

The Pole Star always appears on the horizon, and since it lies exactly in the North direction, it is always at a fixed point, on the Northern horizon. The equator, in fact, is the only place from where you can see both the North as well as South poles of the celestial sphere at the same time. From the equator, every part of the celestial sphere is visible at some time of the year or the other, and no star is circum-polar.

Answer: No

The North Star is only visible from the Northern Hemisphere, and can never be seen from anywhere below the equator, let alone the South Pole! From the South Pole, only the stars in the Southern Hemisphere of the celestial sphere are visible, and these stars are ALWAYS visible- they never rise or set.

The same is the case with the North Pole, from where only stars of the Northern Hemisphere can be seen.

Answer: 25,800 years

The precession of the Earth is primarily due to the fact that the Earth isn't exactly a sphere (it actually is an 'oblate spheroid', its diameter is more at the equator than at the poles), as a result of which gravitational tidal forces exerted by the Sun and Moon try to pull the Earth's bulge at the equator towards the plane of the Earth's orbit around the Sun.

As a result of this precession, the Pole Star also changes gradually over a period of 25,800 years- the next time our Polaris will be where it is near the precession circle now, is in 25,800 years.

Answer: Thuban

Thuban is only around 1/5th as bright as Polaris is, and so is very hard to spot in areas, such as large cities, that suffer from a considerable amount of what is called 'light pollution'. It was the naked-eye star closest to the North Pole of the Celestial Sphere from about 3000 BC to 1900 BC, it being the closest to the North Pole around the year 2700 BC.

Answer: Vega

Vega is the 5th-brightest star in the night-sky, after Sirius, Canopus, Alpha Centauri, and Arcturus. It is also relatively very close to the Sun, only 25 light-years away. Vega, along with two other stars- Altair and Deneb- forms the so-called "Summer Triangle", as these three stars are very clearly visible in the summer-sky of the Northern Hemisphere.

(By the way, the three incorrect options in this question, Canopus, Achernar and Fomalhaut, are all stars in the Southern Hemisphere, and so the question of any of them becoming the Pole Star never arises!)

Answer: Dubhe and Merak

Another constellation with which the Pole Star can be easily located is Cassiopeia. Cassiopeia is a constellation shaped like the letter 'M', just bisect the larger angle of the 'M' and you're there at Polaris!

Since Ursa Major and Cassiopeia are nearly diametrically opposite, in the Northern Hemisphere, either one of the 2 constellations is visible at any given time.

Answer: Sigma Octantis

Sigma Octantis (also called 'Polaris Australis') is found in the constellation Octans, and like I said, is just barely visible to the naked eye; hence, people don't make as much of a deal about it as they do Polaris!

The easiest way to locate the South celestial pole is with the help of the Southern Cross (or Crux), a constellation in the shape of a cross. Just extend the major axis of the cross around 4.5 times its length and you're there! Note that Sigma Octantis is only visible from the Southern Hemisphere and Crux only from South of around 20 degrees North.

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I hope everyone, dwellers of the Northern and Southern hemispheres alike, enjoyed playing this quiz!