The Observatory April 20th 1877
Notwithstanding the incessant watch kept up for three days
in various parts of the world, no news of the supposed planet has reached us;
and according to M L Leverrier, we must now wait at least six years before
another transit could possibly occur. Mr Pogson at Madras, after repeated
searches in a remarkable pure sunset sky, concludes that no planet can exist in
the position assigned.
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Yorkshire has a claim as to why the date of Easter changes each year, so there is no point in blaming other people.
In 664 at Whitby Abbey it was decided to follow the teachings of Rome as to how to calculate the date of Easter. This means that Easter Sunday is the first Sunday following the full Moon after the Spring Equinox. And as the period of time it takes the Moon to orbit the Earth is roughly 29 days or one month which is in fact a modern word and comes from the old word ‘moonth’. The date of Easter Day or Easter Sunday can be as early as March 22nd and as late as April 25th.
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In 1858 C. Evan of Rugby purchased a 4.5 inch Thomas Cooke & Sons telescope. The telescope had a focal length of 78 inches. It was mounted on a fixed equatorial stand with clockwork motion, illuminating apparatus, micrometer with eyepieces, astronomical eyepieces £150 In 2026 this would be around £24,000.
I don’t know if this is the Rev C Evans of Rugby who was
elected a FRAS in 1858, or if he had any connection with Rugby school.
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A striking constellation in the northern skies, Auriga lies above the horns of Taurus the Bull and forms the shape of a kite. Auriga is named after the son of Vulcan who invented the four horse chariot. Its brightest star Capella is the 6th brightest star in the sky.
In 1899 astronomers discovered that Capella was not a single
star but a double star. Like so many stars that appear single to the eye,
Capella actually consists of two stars. But there's more going on with Capella
as there is another component to this system, a pair of small red stars,
meaning that where we see just one star there are actually 6!!
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Capella whose name means the ‘Little She Goat’ has a magnitude of 0.1 and its a G class giant slightly cooler than our Sun which is a G class dwarf and is 43 light years distant.
In brightness it is virtually equal to Vega in the
constellation of Lyra the Lyre but it is of a very different colour, its
yellowish tinge contrast sharply with the steely blue of Vega. Both are
circumpolar from Britain, they can be seen all year round. They lie on opposite
sides of the north pole star and at roughly the same distance from it. This
mean that when Capella is high up Vega is low down and vice versa. From Britain
Capella is overhead during winter evenings while in summer it is Vega that occupies
that position. When at their lowest they are very low just above the horizon.
Slightly to the right and just below Capella is a little but
quite distinct triangle of stars called the Haedi or the kids. They are
referred to as the Kids because where the she goat goes the kids will always
follow!! The top star in the triangle is epsilon, bottom left star is eta and
the bottom right is zeta.
Epsilon is a F class supergiant white star its distance in
not known with any great certainty but it could be about 2,000 light years
away. It normally it shines at around magnitude 3.0 but every 27 years it fades
to magnitude 3.8 where it remains for between 640–730 days – about two years.
Epsilon is eclipsed by an unseen and unknown very large companion star. The star’s last dimming was from 2009 to
2011. The next should begin around 2038!
Zeta is another eclipsing binary where the companion star
cannot be seen with the naked eye and varies between magnitude 3.7-4.1 over a
period of 972 days. Zeta is a K class
giant star lying 790 light years away.
The third component eta which is 243 light years away. It is
a B class star making it much hotter than the Sun, and has a brightness of
magnitude 3.2.
From eta which is
the top star of the Haedi or kids a line drawn down and past zeta will come
across iota or Al Kab which means the ‘Shoulder of the Rein holder’ at a
distance of 490 light years we see iota as a star of magnitude 2.7. It is a K
class giant being cooler than our Sun.
Academy, Saturday 7th February 1874
Mr. Birmingham, of Tuam, has lately been examining the red
stars comprised in the list formed by Schjellerup some years ago, and has
already communicated some interesting results to the Astronomische Nachrichten
and Monthly Notices. He finds curious changes of brightness in some stars,
whilst others have disappeared altogether; and his results are confirmed by
observations made at the Royal Observatory, Greenwich.
The connection between colour and variability in stars is
very curious. It would appear that the red stars are in the condition of a fire
dying out, and that the embers are sometimes raised to a white heat by some
unknown causes only to die down again in an equally mysterious, manner. We are
much in the dark as to the how and the when of many of these changes, but this
much we do know, that solid bodies become brighter as they become hotter, and
in doing so pass from red through yellow to bluish white. But what is the
behaviour of gases under such conditions, is a problem of the immediate future,
and it must be remembered that the changes in stars are probably due to gases;
so that we are hardly yet in a position to speculate.
The interesting
question remains, whether we can justify a division of variable stars into two
classes, the one of short period (a few days), showing the phenomena of
rotation or of the interposition of a dark satellite; the other of periods ranging
from a month to many years, in which the change has a physical origin. The
stars of the latter class are generally red.
www.theramblingastronomer.co.uk
Join me, Martin Lunn MBE every Monday evening from 7.00 pm-9.00 pm on the award-winning Astronomy Show on Drystone Radio, probably the only regular astronomy show on any radio station in the country.
I will take my weekly look at the night sky and look at all
the latest news in astronomy. There will be the astronomical anniversaries this
week plus the latest news from the astronomical societies in the north of
England.
The Astronomy Show every Monday evening only on Drystone Radio live online at www.drystoneradio.com DAB radio in Bradford and East Lancashire, or 102 and 103.5 FM and can also be heard later on the Drystone Radio Podcast.
In 1867 William Henry Mandeville Ellis of St John’s College, Cambridge purchased a 4 inch Thomas Cooke & Sons telescope. I think that William Ellis was an architect.
The telescope came with six astronomical,
one comet, one eclipse and one terrestrial eyepieces. All the eyepieces had to
be packed in a mahogany box.
