Observing

  • 01-10-2016

    Stargazing in October 2016


    The October Night Sky

    The General Weather patterns

    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 line-of-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.

    The Sun

    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.

    The 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 11th 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 16th 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

    Monthly Constellations

    Constellation Convienient Culmination Midnight Culmination Observability
    Cygnus 21:00 Late September Early 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 21:00 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)

    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.


    David J Thomas

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