Author Archives: Brian Jones

ROCK LEGENDS: THE ASTEROIDS AND THEIR DISCOVERERS by Paul Murdin

rock-legendsThis book relates the history of asteroid discoveries and christenings, from those of the early pioneering giants of Herschel and Piazzi to modern-day amateurs. Moving from history and anecdotal information to science, the book’s structure is provided by the names of the asteroids, including one named after the author.

Free from a need to conform to scientific naming conventions, the names evidence hero-worship, sycophancy, avarice, vanity, whimsy, erudition and wit, revealing the human side of astronomers, especially where controversy has followed the christening. Murdin draws from extensive historical records to explore the debate over these names. Each age reveals its own biases and preferences in the naming process.

Originally regarded as ‘vermin of the skies’, asteroids are minor planets, rocky scraps left over from the formation of the larger planets, or broken fragments of worlds that have collided. Their scientific classification as ‘minor’ planets makes them seem unimportant, but over the past decades asteroids have been acknowledged to be key players in the Solar System. This view of their starring role even alters the trajectories of spacecraft: NASA’s policy for new space missions en route to the outer planets is that they must divert to study passing asteroids whenever possible. This book provides for readers a complete tour of the fascinating world of asteroids.

You can purchase a copy of the book by CLICKING HERE.

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THE END OF NIGHT

The End of Night-fcA brilliantly starry night is a wonderful vision. Yet most of us no longer experience true dark.

Exposure to artificial light has been cited in a range of health concerns, while seemingly endless daylight has wrought havoc on our wildlife.

In search of the dark, Paul Bogard travels the globe, from Las Vegas to London, illuminating the problems caused by a lack of darkness and showing exactly what we’ve lost and what we might regain.

 

 

Takes us light years through history, science, psychology, art, folklore and [Bogard’s] own travels, looking for an unpolluted dark and starry, starry night.’
The Times

To seek to let back in a little of the lost starlight and allow more of nature’s shadow to reassert its balm seem to me both modest and wholesome aims, and Bogard’s book does much to make a case for them.’
Observer

Thought provoking . . . convincing that artificial light has blinded us to the beauties of the night. Perhaps it’s time to follow [Bogard] over to the dark side.’
Mail on Sunday

Order your copy of The End of Night  by CLICKING HERE

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THE STARS NIGHT BY NIGHT by Brian Jones

STARS NIGHT BY NIGHTThis modern version of The Stars Night by Night, written by Brian Jones, is a fitting tribute to Joseph Henry Elgie whose own book ‘The Stars Night by Night’ was an inspiring and encouraging guide to those backyard astronomers who turned its pages over a century ago.

Since Joseph Henry Elgie’s original book was published in 1914 we have lost none of our wonder and fascination with the night sky. This book is a celebration of Elgie’s work which will encourage and inspire you to develop your own love affair with the stars.

The constellations were devised by mankind to create harmony out of the night sky’s seemingly-chaotic array of stars. Even though modern astronomers know a great deal about the stars, the age-old fascination humans have for the mysteries of the skies has not diminished because of this.

Written at a level to suit both beginners and more-experienced stargazers, The Stars Night by Night offers the opportunity to observe and discover the constellations that adorn the night sky. Starting with the brilliant Orion, which is visible to astronomers the world over, the book takes us on an odyssey around the heavens, during which we follow a celestial trail, hopping from one constellation to another using the previously described star group to take you on to the next. Every constellation is covered and along our journey we discover their origins and mythology together with snippets of interesting information about the main stars and other celestial wonders which form each group – for example, double and variable stars, star clusters, nebulae and galaxies.

The Stars Night By Night can be ordered by CLICKING HERE

‘The Stars Night by Night’ is relevant for any year and any level of knowledge and provides a portable, interesting, thorough and quirky guide to the night sky. It is sprinkled with quotes from Joseph Henry Elgie, which take us back to his observing experiences, and also includes thoughts and observations from other astronomers of his era and before. Elgie’s wonderfully poetic language would give anyone incentive to look upwards in the night and see and feel the wonders he so beautifully describes.

THE BOOK CONTAINS:

  • Star charts compiled by Garry Blackmore
  • Biography of Joseph Henry Elgie
  • Introduction to the celestial sphere
  • List of constellations with their origins
  • Star charts for every constellation and finder charts to help you to locate numerous star clusters, nebulae and galaxies
  • Glossary / List of further reading

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The North Circumpolar Stars

A circumpolar star or constellation is one that never sets as seen from a given location, but always stays above the observer’s horizon, and can be viewed all year round. Which ones are circumpolar depend on where you are on the planet. For example, from mid-northern latitudes, the stars shown on this chart are circumpolar and are always on view, although the further south you travel, the fewer circumpolar stars there will be (see Circumpolar Stars).

As we have seen, this area of sky is visible from mid-northern latitudes throughout the year and includes the constellations that surround Ursa Minor (the Little Bear) and its prominent leading star Polaris, also known as the Pole Star, and which lies due north.

Generally speaking the Plough, together with the rest of Ursa Major (the Great Bear), can be seen around the zenith or overhead point during mid-evenings in spring, whilst summer evenings see Draco (the Dragon) in this position. Cassiopeia takes their place during the autumn months and the faint and somewhat sprawling Camelopardalis (the Giraffe) in winter.

To start your search of the north circumpolar sky, first of all print out this chart and, facing north, hold it above your head. Now, using the Plough as a guide, rotate the chart and align the pattern of stars shown so they match up with their locations in the sky. Once you’ve done this, the chart will enable you to identify the stars and constellations you can actually see. Once you’ve identified the main constellations shown here, the rest of the (fainter) stars on this chart can be picked out (providing the sky is reasonably dark and clear).

By far the most prominent and well-known group in this region is the Plough, a conspicuous pattern of stars formed from the seven brightest members of Ursa Major. The Plough acts as a useful direction finder to many other stars and constellations. One of these is Polaris. If you extend the line from Merak, through Dubhe in the Plough as shown here this will lead you to Polaris, from which the rest of the stars in Ursa Minor can be picked out.

Now continue the line from Merak and Dubhe roughly as far again past Polaris and this will bring you to Cassiopeia, a distinct W-shaped group of five bright stars. According to legend, Cassiopeia was the mother of Princess Andromeda and wife of King Cepheus of Ethiopia, Cepheus being depicted here as one of the constellations adjoining Cassiopeia. Andromeda lies a little further away from Polaris than Cassiopeia and is best seen in during the autumn.

Other groups in this area of sky include Draco (the Dragon) which winds its way around Ursa Minor, and the two obscure constellations Camelopardalis (the Giraffe) and Lynx (the Lynx). Very clear skies are needed in order to pick out these latter two groups. Neither Camelopardalis or Lynx contain any particularly bright stars and you may need the help of a pair of binoculars to help you identify them.

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Circumpolar Stars

A circumpolar star or constellation is one that is visible all the year round from any particular location on the Earth’s surface. For example, if you were stood at the Earth’s north pole you would be able to see all stars above (to the north) of the celestial equator, but none of the stars or constellations below. Because the celestial equator is 90° away (and equidistant) from the north celestial pole, an observer at the north pole would see the celestial equator on, and extending all around, the horizon. In other words, whatever the time of year, the night sky as seen from the north pole would contain all stars and constellations above the celestial equator, those below (to the south) of the celestial equator being permanently hidden from view.

Taking this a stage further, the south celestial pole will never be visible to an observer located in a country north of the equator, such as England. The reason for this is simply that the Earth itself gets in the way. This means that, for anyone located to the north of the Earth’s equator, the stars close to the south celestial pole never rise above the horizon. However, for northern hemisphere observers, the stars and constellations close to Polaris will never set and, assuming the sky is dark and clear, will always be visible.

The well-known constellations Ursa Major (the Great Bear) and Cassiopeia, are good examples. Lying fairly close to Polaris, this two constellations sweep round the north celestial pole and, even when at their lowest points in the sky, are still located well above the horizon as seen from mid-northern latitudes. In other words, we say that Ursa Major and Cassiopeia are circumpolar.

The bright  stars Castor and Pollux however, which lie further south in the sky in the constellation Gemini (the Twins), rise and set as normal and are not circumpolar. This is because their angular distance from the north celestial pole is so large that, when at their lowest point in the sky, they disappear below the horizon.

Ursa Major and Cassiopeia (along with a few other constellations such as Draco (the Dragon) and Ursa Minor (the Little Bear) are circumpolar as seen from countries at mid-northern latitudes such as England. However, if we travel further south, this situation will change. For example, when seen from Cuba in the Caribbean or Bombay in India the angular distance of Polaris above the northern horizon would be only around 20° which would mean that any stars or constellations lying further away than 20° from Polaris would not be circumpolar. The constellation Ursa Minor would remain circumpolar, although many of the other stars which are circumpolar as seen from England would, at some point, disappear below the horizon. This includes Cassiopeia and Ursa Major which, for part of their daily journey around the sky, would set and be hidden  from view. However, the upside of this (at least from the point of view of observers in Cuba or Bombay) is that many southern hemisphere stars that would be hidden to observers in England would come into view. These include, for example, the brilliant star Canopus in Carina (the Keel) which is well placed for backyard astronomers checking out the night skies of India and the Caribbean.

Just as stargazers in the northern hemisphere have their own circumpolar stars, observers south of the equator, such as those in Australia and New Zealand, have theirs. From locations in these countries, the circumpolar skies are graced by constellations such as the magnificent Crux (the Southern Cross) and, amongst others, the somewhat-fainter Tucana (the Toucan) and Octans (the Octant).

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Magnitude

Hipparchus (Wikipedia)In around 150BC the Greek astronomer Hipparchus (left) divided the stars up into six classes of apparent brightness, the brightest stars being ranked as first class and the faintest as sixth. This system is known as apparent magnitude and classifies the stars and other celestial objects according to how bright they actually appear to the observer.

In 1856 the English astronomer Norman Robert Pogson (1829 – 1891) (right) refined Hipparchus’s system by classing a 1st magnitude star as being 100 times as bright as one of 6th magnitude, giving a difference between successive magnitudes of  5√100 or 2.512. In other words, a star of magnitude 1.00 is 2.512 times as bright as one of magnitude 2.00 and 6.31 (2.512 x 2.512) times as bright as a star of magnitude 3.00 and so on.

The same basic system is used today, although modern telescopes enable us to determine values to within 0.01 of a magnitude. Negative values are used for the brightest objects including the Sun (-26.8), Venus (-4.4 at its brightest) and Sirius (-1.42). Generally speaking, the faintest objects that can be seen with the naked eye under good viewing conditions are around 6th magnitude, whilst binoculars will allow you to see stars and other objects down to around 9th magnitude or so.

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