Download The Night Sky This Month - Usk Astronomical Society

The Night Sky
(October 2016)
BST (Universal Time plus one hour) is used this month.
British Summer Time ends on Sunday 30th October 2016
23:00 hours BST early in the month
22:00 hours BST in the middle of the month
21:00 hours BST at the end of the month
October
The General Weather Pattern
October can continue to be calm and mild from the previous month. Occasionally the weather develops into an
Indian summer in the middle of the month, when unfortunately the nights are foggier. However, mostly October is
the wettest month of the year and storms from the west are more common. At the end of the month and into
November persistent rain and storms can be expected.
From Earth
This is still a comfortable time of year to observe in the evening, even so, the nights are becoming longer than the
days, so chillier nights can be expected. As the Earth moves from the autumnal equinox the days are closing in
rapidly. Throughout this month, the ecliptic is at a very shallow angle of about 15º at sunset. Planets in close lineof-sight to the Sun will be hard to see in the evening twilight.
Throughout this month, there are many lovely photo-opportunities to be had for dedicated observers. This might
be a nice time to take a look at the Andromeda Galaxy, and Cygnus is overhead with the black hole, Cygnus X1,
with which to impress your friends. There are signs in the east of the glories to come in late autumn and winter.
The Milky Way
As was commented on in September, due to worsening light pollution 60% of Europeans no longer see the Milky.
Here in South Wales, however, throughout October, in the hours of darkness, the Milky Way lies within 15° of the
zenith. On two occasions each night, around 22:00 and 04:00, the plane of the Milky Way can be found directly
above our heads at the zenith. Consequently, this is a wonderful time of the year to observe our Galaxy. For
instance, dark regions of dust and gas which obscures light from more distant stars can be seen along the galactic
plane from dark-sky locations.
There are four types of nebulae recognised today and found within our Galaxy, consequently most can be observed
along the band of the Milky Way. For the same reason, star clouds such as open clusters are found in this region.
Sun
Conditions apply as to the use of this matter. D J Thomas
The Sun, is in Virgo except for the last day this month, and is as I write, solar activity is reducing. The Sun no
longer rises as high in the sky as it does in the summer, however, If you have any news sunspot activity your
fellows would be interested, so let us know. Don’t forget to ask experienced members for help if you want to
observe the Sun.
Moon
The New Moon is on 1st at about 00:11 in the constellation of Virgo.
The First Quarter is on 9th at about 04:35 in the constellation of Sagittarius.
The Full Moon is on 16th at about 04:25 in the constellation of Pisces.
The Last Quarter is on 22nd at about 19:15 in the constellation of Cancer.
The second New Moon is on 30th at about 17:40 in the constellation of Libra.
The Moon is at perigee (nearest Earth) on the 16th and at apogee (most distant from Earth) on the 4th. A second
apogee occurs on the 31st.
The Planets
Mercury raises steeply an hour and a half before the Sun in early October but closes rapidly on the Sun until it
is at superior conjunction on the 27th October and is unobservable at this time. However, between the middle of
September and the middle of October is a good time, this year, for observing Mercury. The conjunction with
Jupiter on the 11th is, I suggest, too dangerous to observe.
Venus is in the south-west in the evening twilight throughout October and its observational position continues
improving.
Mars is in Sagittarius throughout the month and gains a little height at sunset in the south-south-west as the
month progresses
Jupiter reappears again in the morning twilight in the middle of the month. On the 11 th Jupiter approaches
within 1° of Mercury as they both rise steeply in the morning twilight. I feel this may very well be too dangerous
to observe.
Saturn is in Ophiuchus throughout October and appears low in the south-west as the Sun sets and as it moves
towards conjunction at the end of November; it is way past its best. By the end of the month, Saturn is only 8°
above the horizon at sunset so observe Saturn as soon as you can this month, in the south-west.
Uranus is at opposition on the 15th and is visible throughout the night this month. At a magnitude of 5.70 it
may well be seen with binoculars. A small telescope might show a blue hue, but since Uranus usually has few
features, little else may be seen even with a larger amateur instrument. It can be found in the constellation of
Pisces at RA 1h 24m 17s, Declination 8º 10' 19"; due south at about 01:00 on the 10th.
Neptune rises an hour or so before Uranus and is slightly better placed for observers. It is just past opposition,
so at the beginning of the month at around 11:00, it can be found culminating in the constellation of Aquarius at
RA 22h 46m 58s, Declination -8º 42' 02". It has a magnitude of 7.83.
Meteors
The Orionids can be seen emanating over the eastern horizon at about 11.00 pm between 16 th to 27th October.
With a ZHR around 25, these meteors can be very fast with persistent trains; the meteoroids hit the Earth’s
atmosphere at around 67 km/s. The maximum is on the morning of 22nd. This is the second shower associated
with Comet P/Halley (the first, the Eta Aquarids, is in May), and has its radiant in the north of Orion. At this time
of year Orion rises around midnight, but unfortunately this year, the third quarter Moon rises with it.
The Taurids can be seen emanating over the eastern horizon at sunset in the east from the 20th October to 30th
November. Its maximum is wide-ranging, peaking around the 1st and 12th of November, with double radiants
between Taurus and Aries. The shower can produce slow, but brilliant meteors with a ZHR ~ 10. This shower is
associated with Comet P/Encke.
Constellation Culminations from Usk
A celestial body or region of the sky is said to culminate when it crosses an observer’s meridian (an imaginary line
drawn overhead and through both poles). All other things being equal objects are usually best observed in this
position as the light from them travels through the least amount of atmosphere.
Constellation
Convenient Culminations Midnight Culminations
Observability
Cygnus
20:00 Mid-October
Mid-August
Whole constellation at zenith
Delphinus
20:00 Mid-October
Mid-August
Whole constellation
Vulpecula
20:00 Mid-October
Mid-August
Whole constellation
Equuleus
20:00 Late October
Late August
Whole constellation
Capricornus
20:00 Late October
Late August
Whole but poor; low in the murk
Microscopium
20:00 Late October
Late August
Unfavourable and partially hidden
Cepheus (pronounced see’ fee us)
In Welsh
Seffews nm.
Conditions apply as to the use of this matter. D J Thomas
To find Cepheus in mid-October, Face north at around 23:00 trace an
imaginary line from the Plough’s pointers up past Polaris. At an equal
distance on the opposite side from the Plough is Cepheus, a circumpolar
constellation and therefore visible no matter what the season or time of
night. King Cepheus sits on a throne next to his queen Cassiopeia. The
legs and seat of his throne make a rough square, which at this time looks
like an upside down house (or throne); the back of the seat comes to a
point.
As legend suggests, Cepheus is a fairly innocuous constellation and its
brightest star, Alderamin, has a magnitude of only 2.4. The name seems
to derive from medieval Arabic, Adh-Dhira' al-Yamin meaning ‘Right
Forearm’. In about 5300 years’ time, because of precession, it will
become the pole star, as it was around 18,000 B.C.
It was in this constellation in 1784 that English astronomer John
Goodricke first measured the regular variations in brightness of the star δ Cephei. His measurements were
included in a report to the Royal Society and δ Cephei became the definitive Cepheid variable, in honour of
Goodrickes work. Goodricke himself was something of a tragic figure. He was born a deaf-mute and died at the
age of only 21 years, without ever seeing the importance of his work realised. Although in his paper to the Royal
Society he had forecast that, "Such enquiries may probably lead to some better knowledge of the fixed stars,
especially of their constitution and the cause of their remarkable changes."
In the early years of the twentieth century Henrietta Leavitt established the relationship between the brightness of
these stars and their period of variability. This period-luminosity relationship made it possible to find the distance
to celestial objects as far away as the nearest galaxies.
Myth
In Mesopotamian tradition, this constellation was associated with a one-time king of Babylon, the son of the god
Bel (Baal in the Old Testament).
Greek Myth
Cepheus, the king of Joppa, a city in Phoenicia (later Palestine) was married to Cassiopeia. The fertile couple
were blessed with twenty sons and two beautiful daughters, Aeropa and Andromeda. Andromeda was particularly
beautiful, inheriting her mothers' renowned good looks.
In her vanity Cassiopeia carelessly boasted that both she and Andromeda were more beautiful than the fair Nereids,
or sea nymphs, who complained bitterly to their protector, Poseidon, the god of the sea, brother of Zeus and Hades.
Poseidon was surly and quarrelsome by nature and easily angered, and in his wrath he commanded a great flood
and a female sea monster (believed by some to be Draco) to devastate Phoenicia. In his desperation King Cepheus
sought the advice of the oracles that told him that his only hope was to sacrifice Andromeda to the monster.
By good fortune, Perseus, son of Zeus, was returning home from Greece having recently slain a Gorgon, Medusa,
a creature so ghastly that the mere sight of her face ossified those unlucky enough to gaze upon her countenance.
He saw an angry mob calling for the immediate sacrifice of the princess Andromeda, while the distraught King and
Queen stood near the water’s edge. Perseus was at once smitten by Andromeda's loveliness and flew down to her
parents offering to slay the monster, albeit on his own terms. They agreed that should he slay the monster then
Andromeda would become his wife and go with him to his home in Greece. After a brief battle the monster was
turned to stone having seen the Gorgon’s face.
Andromeda was happy to honour her parents' agreement
There is no record of Cepheus's or Cassiopeia’s earthly fate, but after their deaths Poseidon himself transported
both Cepheus and Cassiopeia to the heavens.
Conditions apply as to the use of this matter. D J Thomas