StarFish.net

Introduction

Welcome to StarFish.net – Astronomical Information from the UK Hydrographic Office

This page provides some astronomical information on a monthly basis for those of you living in the Taunton area. Timings are in BST (British Summer Time) unless otherwise noted. Latest additions or updates are highlighted with a red border.

This month we have sections on:

Fall back to Greenwich Mean Time ...

Clocks in the United Kingdom and the rest of the European Union go back one hour on the last Sunday of October under the provisions of Directive 2000/84/EC of the European Parliament and of the Council of 19 January 2001 on summer-time arrangements. Consequently, on October 25^th at 02:00 BST (British Summer Time) clocks are moved back to 01:00 GMT (Greenwich Mean Time). Any event listed here taking place after 01:00 GMT on October 25^th will be given in terms of Greenwich Mean Time.

2020 Astronomical and Calendarial Sheet

Additional information on the phases of the Moon, the seasons, summer times, eclipses, chronological cycles and eras, religious calendars, the civil calendar and holiday dates in the United Kingdom can be found in HMNAO's Astronomical and Calendarial Sheet No. 107 for 2020. This is a pdf document for which a document reader can be downloaded by clicking on the Adobe Reader icon above.

Remember ...

This web page can also be accessed from outside the UK Hydrographic Office on http://astro.ukho.gov.uk/nao/taunton.html.

↻ The last update to this page was made on Monday, 2020 October 19 at 09:46:02 BST.

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The Sun

An animated view of the Sun's disk over the last twenty-eight days is shown in the image on the left. North is at the top of the image and east is to the left. These images come from the Helioseismic and Magnetic Imager instrument on the NASA Solar Dynamics Observatory (SDO) satellite. More multi-wavelength data from the SDO can be found here.

Active region AR2776, a Solar Cycle 25 feature which has exhibited a significant number of minor B-class solar flares, lies in the south-eastern quadrant of the Sun and has quadrupled in size since it appeared five days ago. A new feature, AR2777, is about to cross the south-western limb of the Sun only a day after it first appeared. The total number of spotless days for 2020 remains at two hundred and four, or 70% of the year so far. Solar winds are currently blowing with velocities of around 360km/s and the planetary K_p geomagnetic activity index is likely to peak at 1 (quiet) today. A selection of small coronal holes are distributed across the surface of the Sun. Solar winds emanating from these features could reach the Earth between October 21^st and October 25^th. The overall amount of solar activity remains at very low levels.

NASA reported that a reversal of the Sun's magnetic field took place at the start of 2014 indicating that the maximum of Solar Cycle 24 had been reached. A plot of sunspot numbers, both observed and predicted versus time indicates that the solar maximum of Solar Cycle 24 was more complex than had been previously predicted. The maximum was double-peaked in a similar manner to that of the previous maximum of 2001/2002. The individual peaks occurred in 2011 and 2014 with the latter being the larger of the two. However, sunspot numbers were significantly down on the predictions made for the maximum — indeed Solar Cycle 24 may be the weakest in the last 100 years or so i.e. since Solar Cycle 14.

The declining phase of the solar cycle brings increased numbers of cosmic rays to the Earth, an increased frequency of 'pink' aurorae and a slight dimming of the Sun of approximately 0.1% in terms of the total solar irradiance. TSIS-1 was launched on December 15^th 2017, which will monitor the Sun over a five-year period covering the whole of the current solar minimum. Cooling and contraction of the Earth's upper atmosphere in response to the changes on the Sun due to the solar minimum also delayed the orbital decay of satellites such as the Chinese space station, Tiangong 1, which returned to Earth on Monday April 2^nd 2018 at 00:16 UTC. The Sun's magnetic field and solar winds provide some protection for the Earth from cosmic rays. A recent paper in the journal Space Weather claims that this solar minimum could see a rise in the number of cosmic rays reaching the Earth by as much as 30% due to the weakening magnetic field of the Sun and reduced levels of solar winds. This could mean an increased risk of radiation exposure for travellers on commercial airlines and possible changes to the climate.

During the post maximum phase of the solar cycle individual energetic events can spawn some of the most powerful flares and coronal mass ejections of the cycle. The so-called Carrington event on September 1^st–2^nd 1859 during Solar Cycle 10 is a good example of just what might ensue from this type of violent outburst. On 2020 September 15^th NASA and NOAA announced that a minimum of the Sun's activity had been reached in December 2019 bringing to an end the old Solar Cycle 24. Predictions are that the new Solar Cycle 25 will be a weak one, similar to its predecessor, peaking in 2025. It is likely to be a deep minimum with long periods without much sunspot or flare activity. Space weather will be dominated by solar winds and cosmic rays rather than sunspots and solar flare activity.

The latest information on solar activity can be found at SpaceWeather.com and at the Space Weather Prediction Center Space Weather Enthusiasts Dashboard.

If an auroral display is possible or likely, warnings can be received from AuroraWatch UK. More UK-focused geomagnetic data can be found at the British Geological Survey web site.

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The Moon

The sequence of Moon phases for this month and their designations are shown in the following animation:

	Moon phases for October 2020 are as follows:
	Full Moon	—	Thursday October 1st at 22:05 BST 'Harvest Moon'
	Last Quarter	—	Saturday October 10th at 01:40 BST
	New Moon	—	Friday October 16th at 20:31 BST Lunation 1210
	First Quarter	—	Friday October 23rd at 14:23 BST
	Full Moon	—	Saturday October 31st at 15:49 BST 'Hunter's Moon' Most distant / smallest Full Moon of 2020 Calendrical Blue Moon for October

The Moon is at apogee (i.e. furthest from the Earth) on Saturday October 3^rd at 18:22 BST when it is 406,321 km from the Earth. It is at perigee (i.e. nearest to the Earth) on Saturday October 17^th at 00:46 BST when it is 356,912 km from the Earth. The Moon is again at apogee on Friday October 30^th at 18:45 GMT when it is 406,394 km from the Earth.

The combination of the Moon being close to perigee and the phase of the Moon being either new or full (i.e. the Sun, Earth and Moon are in alignment) as it is around Friday October 16^th and shortly thereafter leads to 'perigean (or proxigean) spring tides' i.e. spring tides with a tidal range slightly larger than those of normal spring tides.

On Saturday October 3^rd, the Moon occults the planet Mars in the south-eastern part of the constellation of Pisces. This occultation by the waning gibbous moon is visible from south and south-easternmost South America, most of western Antarctica, the Falkland Islands, Ascension Island and south-western Africa. This occultation is not visible from the United Kingdom.

Please follow the New Moon link above to find out more about our Crescent Moon Watch program which involves making sighting of the new crescent moon as early as possible after the instant of New Moon.

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Blue Moons & Full Moon Names

Many of you will have heard of the term 'Blue Moon' in phrases such as 'once in a blue moon ...' meaning a rare or infrequent event. Some of you may also be aware that this month's second full moon is being referred to as a blue moon. January and March in 2018 also had two full moons whereas February 2018 had no full moon. The last time this sequence of events occurred was in 1999. It will happen again in 2037.

There are two 'definitions' of a blue moon describing an extra full moon within a subdivision of a year. One refers to the third of four full moons in a season and, more recently and erroneously, the second full moon in a calendar month. This definition came from an article in the March 1946 edition of Sky & Telescope by James Hugh Pruett and was propagated until 1999 by this well-known astronomy magazine. If you divide the year up into quarters using solstices and equinoxes as limiting dates then the blue moons are termed 'seasonal'. If you adopt calendar months as your criterion, where two full moons occur within a month, then the blue moons are termed 'calendrical'.

The blue part of the name has nothing to do with the colour of the Moon, although on very rare occasions smoke and/or dust in the atmosphere can give the moon a somewhat bluish tint. The term blue moon may be linked to the belief that this second moon was a 'betrayer' moon or 'belewe' moon in the determination of Lent.

Blue moons of both types are listed in sequential order for the period 2000 to 2040 in the table below.

The above timings are predicated on GMT-based dates. Whichever scheme one adopts, a blue moon is not as rare an event as it might seem. In fact, seasonal blue moons happen seven times in nineteen years or once every 2.7 years on average.

You can also have a 'Black' moon; there are several definitions for this type of moon. One is the second occurrence of a new moon in a calendar month. It can also be the third new moon within a season of four new moons. Both of these are analogous to the blue moon definitions. The third is the absence of a full moon in a calendar month and the fourth is the absence of a new moon in a calendar month. The last two can only happen in February in addition to the previous January and the following March having two full or new moons respectively. February 2018, is an example of the third definition which occurs about once every 19 years.

Some people may have heard of 'dry' moons and 'wet' or 'Cheshire' moons, where the cusps or horns of the crescent moon point upwards. In the northern hemisphere, the dry moon is a summertime moon whereas the wet moon is a wintertime one. Both of these terms are thought to come from Hawaiian astrology where the crescent moon is regarded as a bowl for collecting water.

Folklore has also given us a plethora of names for each month's Full Moon. Here are a selection of names from a variety of cultures including Native American Indian, Colonial American, Pagan, English Medieval or Old English and Anglo-Saxon. I should point out that this list is by no means an exhaustive one.

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The Planets

Planets visible with the naked eye ...

Mercury is barely visible, very low in the west south-western evening twilight sky during most of October as it moves closer to the Sun after greatest eastern elongation on Thursday October 1^st. It fades noticeably from magnitude +0.0 at the start of the month to +3.0 at the end of the third week of October when it disappears from the evening sky as it moves towards inferior conjunction on Sunday October 25^th. Mercury is 7° south of the waxing crescent moon on Saturday October 17^th.

Venus remains prominent in the eastern morning twilight sky, rising three to four hours before the Sun. It fades slightly from magnitude −4.1 at the start of the month to −4.0 at the end of October. Venus lies 0.09° south of Regulus (α Leonis) on Saturday October 3^rd and lies 4° south of the waning crescent moon on Wednesday October 14^th.

Mars rises in the eastern sky around sunset and sets around sunrise. It spends the remainder of the year in the southern part of the constellation of Pisces. Mars brightens somewhat from magnitude −2.4 at the start of the month to −2.6 on Tuesday October 6^th when it makes its closest approach to the Earth since 2003, outshining Jupiter in the process. It will not be this close to the Earth again until September 2035. Mars fades noticeably to magnitude −2.2 by the end of October. Mars lies 0.7° north of the waning gibbous moon on Saturday October 3^th. In certain parts of the world this event can be seen as an occultation by the Moon. It reaches opposition on Tuesday October 13^th and lies 3° north of the waxing gibbous moon on Thursday October 29^th.

Jupiter is visible in the southern evening twilight sky rising in the early afternoon and setting before midnight in the south-western sky. It lies in the eastern part of the constellation of Sagittarius until the latter half of December. Jupiter fades slightly from magnitude −2.3 at the start of the month to −2.2 at the end of October. It lies 2° north of the waxing crescent moon on Thursday October 22^nd. The separation between Jupiter and Saturn decreases from 7.3° to 5.2° during October.

Saturn is visible in the southern evening twilight sky rising in the early afternoon and setting before midnight in the south-western sky. It lies in the eastern part of the constellation of Sagittarius until mid-December. Saturn fades slightly from magnitude +0.5 at the start of the month to +0.6 at the end of October. It lies 3.0° north of the first quarter moon on Friday October 23^rd. The separation between Saturn and Jupiter decreases from 7.3° to 5.2° during October.

Planets visible with Binoculars ...

Uranus rises in the east north-eastern sky around sunset and sets just after sunrise in the west north-western sky. It is a blue-green object which remains at magnitude +5.7 for the whole of October. Uranus lies in the southern part of the constellation of Aries where it remains for the rest of the year. Uranus is approximately 11.3° north east of the fourth magnitude star Omicron Piscium. This planet can also be glimpsed with the naked eye under optimum conditions.

Neptune rises shortly before sunset in the eastern twilight sky and sets two to three hours before sunrise in the western sky. It lies in the north-eastern part of the constellation of Aquarius where it will remain for the rest of the year. Neptune is approximately 6.8° to the north east of the third magnitude star Lambda Aquarii. It is a bluish object of magnitude +7.8 for the whole of the month. It can be visible with good binoculars under optimum conditions although it can also be difficult to distinguish Neptune from other stellar objects of a similar magnitude.

... & Telescopes!

Pluto rises about in the mid-afternoon in the south-eastern sky and sets just before midnight in the south-western sky. It lies in the north-eastern part of the constellation of Sagittarius about 3.4° to the east of Jupiter in mid-October. Strictly speaking, this is a dwarf planet which was demoted from the ranks of the 'bona-fide' planets at the International Astronomical Union General Assembly in Prague in 2006. At magnitude +14.8, you will need a much larger telescope to find this remote member of the Solar System.

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Zodiacal Light

The rarely-spotted Zodiacal Light is best seen in the half hour or so before astronomical twilight starts in the morning or in the half hour or so after astronomical twilight ends in the evening. It is best seen when the ecliptic, the path the Sun takes in the night sky, is at a steep angle to the horizon. In northerly latitudes, this occurs in the western evening post-twilight sky in February and March and the eastern morning pre-twilight sky in September and October. The Zodiacal Light appears as a large, softly radiant pyramid of light with its base near the horizon and its axis centred on the Zodiacal constellations. It appears to be about as bright as the Milky Way, consequently a dark, unpolluted sky without haze is essential to see this phenomenon. Beware, it can easily be confused with the twilight itself. In the photograph, the Zodiacal Light is on the left and the Milky Way is on the right. For Taunton, astronomical twilight starts in the morning at around 05:20 BST at the beginning of the month and at 05:10 GMT at the end of the month. The cause of this so-called 'false dawn' is sunlight reflecting of a lens-shaped cloud of dust in the plane of the inner solar system.

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Meteor Showers

The Orionid meteor shower is active over very nearly the whole of October and the first week of November. The shower exhibits a moderate number of fast meteors and fireballs with long trains, reaching a peak of activity at the end of the third week of October. These meteors are debris connected with the orbit of 1P/Halley's Comet which is encountered by the Earth at this time of year. The waxing crescent moon sets well before midnight on the night of October 20^th-21^st when the shower is at its maximum. This means that moonlight will not interfere with the optimum early morning observation window for this shower when up to 20-30 meteors per hour can normally be observed. Occasionally, the peak rate can reach 70 meteors per hour on a 12-year period due to the influence of Jupiter. Unfortunately, we are close to the minimum of that cycle. The radiant, the point from which the meteors appear to emanate, lies on the border of the constellations of Orion and Gemini. Subsidiary maxima close to the main peak of activity ensure that rates will remain high for several days around October 21^st.

The Draconids, a weak shower with a rate of around ten meteors per hour, is active during the first week or so of October, peaking on Thursday October 8^th. The shower is best seen when comet 21P/Giacobini-Zinner returns to perihelion and consists of extremely slow-moving meteors. The radiant lies close to the head of the constellation of Draco the Dragon, making the radiant circumpolar from our latitudes and best seen during the first half of the night. Fortunately, the Moon is close to the last quarter phase and consequently moonlight does not interfere with the observation window this year. No other regular showers exhibiting significant numbers of meteors are active this month. Further information on these and other meteor showers occurring during 2020 can be found at the International Meteor Organization and their 2020 Meteor Shower Calendar.

It is worth noting that bright sporadic meteors and fireballs are possible at any time e.g. the fireball observed over many parts of England and Scotland on Saturday March 3^rd 2012 at 21:40 GMT. Larger events, known as bolides, are rarer. Typically, this is a very bright fireball reaching an apparent magnitude of −14 or so, perhaps three times as bright as a full moon. Even rarer are the superbolides, events with apparent magnitudes of −17 or so, around 50 times brighter than the full moon. A recent example of a superbolide was the Chelyabinsk meteor of 2013 February 15^th at 03:20 UTC which may have been a 20-metre diameter near-Earth asteroid.

Another loosely-related phenomenon is the re-entry of space debris from space vehicles and satellites whose orbits are decaying to the point where they burn up in the Earth's atmosphere. A couple of well-reported examples of this occurred at around 23:00 BST on Friday September 21^st 2012 as well as the return of the GOCE satellite just after midnight on Tuesday November 12^th 2013.

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Comets

There are a number of comets around the sky at the moment. However, most of them require telescopic assistance to see them and some may be too far south in the sky to be seen by observers based in the United Kingdom. Here is a brief summary of the comets that may be accessible to observers with binoculars or small telescopes in the northern hemisphere.

88P/HOWELL is a magnitude +8.6 object visible with binoculars or a small telescope in the constellation of Scorpius for the first two days of the month. It then crosses over into the neighbouring constellation of Ophiuchus until the middle of the month. The comet then moves into Sagittarius for the remainder of the month. By the end of month, it will have faded by about half a magnitude. It can just be seen very low in the southern sky in the evening twilight. It reached perihelion on Saturday September 26^th 2020 and is likely to be difficult to find.

C/2020 M3 (ATLAS) is a magnitude +9.2 object best seen with binoculars or a small telescope in the southern sky two to three hours after midnight. It should brighten by nearly a magnitude during October and spends the first half of the month in the constellation of Eridanus and then moves into Lepus for the latter half of October. C/2020 M3 was discovered on June 27^th this year and will reach perihelion on October 25^th.

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Sky chart for mid-October at 22:00 BST for Taunton

The above sky chart, generated from the Heavens-Above.com web site, shows what the night sky looks like at 22:00 BST on Friday October 16^th 2020 from Taunton. The night sky will look the same an hour later at 23:00 BST at the beginning of the month and an hour earlier at 20:00 GMT (21:00 BST) at the end of the month. Please click on the chart to see a full-sized sky chart image. If you want to generate your own star chart for Taunton for another date and/or time, please follow this link

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Rise/set times (BST) for the Sun & Moon for Taunton

In October 2020, the amount of daylight (measured from sunrise to sunset) decreases from 11 hours 36 minutes at the start of the month to 9 hours 44 minutes at the end of the month. Total daylight (sunrise to sunset) for the month is 330 hours 20 minutes.

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