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:
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. 108 for 2021. This is a pdf document for which a document reader can be downloaded by clicking on the Adobe Reader icon above.
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 Thursday, 2021 August 05 at 13:23:18 BST.
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.
There is a single, high-latitude active region, designated AR2850, in the south-western quadrant of the Sun. It is approaching the limb and has gone through a phase of rapid growth. However, it is not showing any signs of producing significant solar flares — indeed, it is starting to decay. A new sunspot may be emerging not too far from the south-eastern limb of the Sun, although it appears to be experiencing a difficult birth. The total number of spotless days for 2021 remains at fifty one, or 24% of the year so far. Solar winds are currently blowing with velocities of up to 300 km/s and the planetary Kp geomagnetic activity index is likely to peak at 1 (quiet) today. There are two or possibly three coronal holes on the visible disk of the Sun, one in the north-western quadrant and one or two in the southern hemisphere, spanning the central meridian. Solar winds emanating from these coronal holes could reach the Earth on August 6th–7th, possibly leading to minor geomagnetic storms. 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 15th 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 2nd 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 1st–2nd 1859 during Solar Cycle 10 is a good example of just what might ensue from this type of violent outburst. On 2020 September 15th 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 sequence of Moon phases for this month and their designations are shown in the following animation:
|Moon phases for August 2021 are as follows:|
|New Moon||—||Sunday August 8th at 14:50 BST
|First Quarter||—||Sunday August 15th at 16:20 BST|
|Full Moon||—||Sunday August 22nd at 13:02 BST
|Last Quarter||—||Monday August 30th at 08:13 BST|
The Moon is at apogee (i.e. furthest from the Earth) on Monday August 2nd at 08:35 BST when it is 404,410 km from the Earth. It is at perigee (i.e. nearest to the Earth) on Tuesday August 17th at 10:16 BST when it is 369,124 km from the Earth. It is again at apogee on Monday August 30th at 03:22 BST when it is 404,100 km from the Earth.
Please follow the New Moon link above to find out more about our Crescent Moon Watch program which involves making a sighting of the new crescent moon as early as possible after the instant of New Moon each month.
There are four eclipses visible from the Earth during 2021 — two lunar eclipses, one total and one partial and two solar eclipses, one annular and one total. Parts of two of the eclipses are visible from the United Kingdom, namely the partial phase of the annular eclipse of the Sun and some of the partial eclipse of the Moon. The total eclipses of the Sun and Moon are not visible from the United Kingdom.
A total eclipse of the Moon occurred on Wednesday May 26th 2021. It was visible in its entirety from south-westernmost Alaska, the Aleutian Islands, the Hawaiian Islands, Polynesia, the central Pacific Ocean region, New Zealand, Melanesia, Micronesia, central and eastern Australia and parts of Antarctica. Parts of the eclipse were visible from the Americas except north-eastern Canada and eastern parts of South America, Indonesia, the Philippines, Japan, eastern Asia, north-easternmost Russia and the eastern half of the Indian Ocean. The eclipse began at 08:46 UT and ended at 13:51 UT. The Moon entered the umbral shadow at 09:45 UT. Totality began at 11:10 UT and ended at 11:28 UT. The Moon left the umbral shadow at 12:53 UT. The eclipse was not visible from the United Kingdom.
An annular eclipse of the Sun occurred on Thursday June 10th 2021. It was visible as a partial eclipse from the north-eastern part of North America, the Arctic Ocean, most of Greenland, Iceland, northern Europe (including the British Isles), Scandinavia, most of Russia, Mongolia and most of China. The path of annularity began over central Ontario and crossed over north-western Quebec, the southern part of Baffin Island, the north-western part of Greenland, the North Pole (for the only time this century) and the north-eastern part of Siberia. The eclipse began at 08:12 UT and ended at 13:11 UT. The annular phase started at 09:50 UT and ended at 11:33 UT. The maximum duration of annularity of 3m 48s took place at 10:42 UT over the sea between Ellesmere Island and north-western Greenland. From Taunton, the partial eclipse started at 10:04 BST and ended at 12:18 BST. The maximum obscuration occurred high in the south-eastern sky at 11:08 BST when 21.4% of the Sun was obscured.
A deep partial eclipse of the Moon occurs on Friday November 19th 2021. It is visible in its entirety from most of North America except the easternmost parts, Mexico, the eastern and central Pacific Ocean regions and north-eastern parts of Russia. Parts of the eclipse are visible from Scandinavia, the British Isles, Iceland, South and Central America, Australasia, Japan, the Philippines, most of Indonesia, eastern and northern Asia. The eclipse starts at 06:00 UT and ends at 12:06 UT. The umbral phase of the eclipse starts at 07:18 UT and ends at 10:47 UT. The maximum of the eclipse occurs at 09:03 UT with a magnitude of 0.978. The eclipse is visible in part from the United Kingdom. From Taunton, the partial eclipse starts at 06:00 UT and ends at 07:35 UT at moonset.
A total eclipse of the Sun occurs on Saturday December 4th 2021. It is visible as a partial eclipse from Antarctica, the South Atlantic Ocean, the southernmost part of South Africa, the South Indian Ocean, Tasmania and the southernmost part of Australia. The path of totality starts approximately 450 km to the east of the Falkland Islands, crosses the Weddell Sea and the Ronne Ice Shelf, Ellsworth Land and ends over the Amundsen Sea, approximately 500 km from the coast of western Antarctica. The eclipse starts at 05:29 UT and ends at 09:38 UT. The total phase of the eclipse starts at 07:00 UT and ends at 08:07 UT. The maximum duration of totality is 1m 57s at 07:33 UT over the Ronne Ice Shelf in western Antarctica. The eclipse is not visible from the United Kingdom.
Further information on all the eclipses in 2021 can be found on the Eclipses Online web pages. This web site provides information on both solar and lunar eclipses in the period from 1501 CE to 2100 CE. Global circumstances of both solar and lunar eclipses are provided as well as local circumstances of the solar eclipses based on a gazetteer of approximately 1500 locations worldwide. Eclipses for next year, 2022, are also available.
Mercury reaches superior conjunction with the Sun on Sunday August 1st. It starts its best evening apparition of the year for southern hemisphere observers at the end of the second week of August. However, for northern observers, it is the worst apparition of the year with Mercury setting shortly after the Sun. Mercury is very low in the western evening twilight sky, fading from magnitude −2.0 at the start of the month to magnitude 0.0 at the end of August. It lies 4° south of the waxing crescent moon on Tuesday August 10th, 1.2° north of Regulus (α Leonis) on Wednesday August 11th and 0.08° south of Mars on Thursday August 19th.
Venus lies in the western evening twilight sky at an elongation which decreases from 33° to 40° as the month progresses. Despite the increase in elongation, its southward movement in declination means that Venus becomes more difficult to observe as the month progresses. Venus brightens slightly from magnitude −3.9 at the start of the month to −4.0 at the end of August. It lies 4° south of the waxing crescent moon on Wednesday August 11th.
Mars rises in the east north-eastern sky about an hour and a half after sunrise and sets about an hour or so after sunset in the west north-western sky. Its elongation decreases from 22° to 13° as the month progresses making it increasingly difficult to find in the bright evening twilight sky. Mars remains in the southern part of the constellation of Leo throughout August. It also remains at magnitude +1.8 throughout the month. Mars lies 4° south of the waxing crescent moon on Tuesday August 10th and 0.08° north of Mercury on Thursday August 19th.
Jupiter reaches opposition on Friday August 20th, rising at sunset and setting at sunrise. It lies in the constellation of Aquarius for nearly the first three weeks of the month, crossing into Capricornus for the remainder of August. Jupiter continues its retrograde or westward motion during August and brightens slightly from magnitude −2.8 at the start of the month to magnitude −2.9 at the end of August. It lies 4° north of the full moon on Sunday August 22nd. The four large Galilean satellites are at their brightest and widest apparent separation from Jupiter this month.
Saturn reaches opposition on Monday August 2nd, rising just before sunset and setting an hour or so before sunrise. It lies in the central part of the constellation of Capricornus for the whole of August. Saturn continues its retrograde or westward motion during August and fades slightly from magnitude +0.2 at the start of the month to magnitude +0.3 at the end of August. It lies 4° north of the full moon on Friday August 20th. The north side of the ring plane is exposed with a tilt of 18° with the ring system spanning nearly 42 arcminutes while the planet's disk is only 19 arcseconds wide.
Uranus is visible in the south-eastern morning sky throughout August, rising in the late evening. It is a blue-green object which brightens slightly from magnitude +5.8 at the start of the month to magnitude +5.7 at the end of August. Uranus lies in the south-western part of the constellation of Aries where it remains for the remainder of the year. It lies approximately 5.7° north of the fourth magnitude A9 giant star 87 Ceti (μ Ceti). This planet can also be glimpsed with the naked eye under optimum conditions.
Neptune is visible in the southern morning sky throughout August, rising in the mid-evening. Neptune is a bluish object which remains at magnitude +7.8 throughout the month. It lies in the north-eastern part of the constellation of Aquarius where it remains for the remainder of the year. Neptune lies approximately 10.5° to the north east of the third magnitude M2.5 red-giant star Hydor (λ Aquarii). It is normally visible with good binoculars under optimum conditions although it can also be difficult to distinguish Neptune from other stellar objects of a similar magnitude.
Pluto rises an hour before sunset and sets before morning twilight, making it visible in the southern sky around midnight throughout August for observers using larger telescopes. It lies in the north-eastern part of the constellation of Sagittarius about 11.4° to the south west of the third magnitude binary pair known as Dabih Major and Dabih Minor (β Capricorni) in mid-August. Strictly speaking, this is a dwarf planet which was demoted from the ranks of the 'bona-fide' planets at the 2006 International Astronomical Union General Assembly in Prague. At magnitude +14.7, you will need a much larger telescope to find this remote member of the Solar System.
The peak of the Perseid meteor shower will be visible this month. These meteors are associated with the comet 109P/Swift-Tuttle which orbits the Sun every 133 years. Although the Perseids are active from Saturday July 17th to Tuesday August 24th, they reach the peak of their activity on the evening of Thursday August 12th between 20:00 BST and 23:00 BST so it is worth trying to observe them in the early hours of either Thursday August 12th or Friday August 13th. The radiant, the point in the sky from which the meteors appear to originate, is reasonably high in the north-eastern sky, and lies between the 'W-shaped' constellation of Cassiopeia and the top of the inverted 'Y-shape' of Perseus below Cassiopeia. This year, the peak of the shower occurs four days after new moon meaning skies will be dark in the post-midnight period. At the peak of the shower, we would expect to see as many as 110 meteors per hour on a dark night. The Perseids are often bright, quite fast and frequently leave persistent trails. Their numbers also increase somewhat as morning twilight approaches as the Earth moves into the oncoming stream of meteors. The Perseids also produce a significant number of fireballs i.e. meteors that appear to be brighter than the planet Venus.
No other significant meteor showers visible from our latitudes are active this month. Further information on meteor showers can be found at the International Meteor Organization and their 2021 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 3rd 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 Friday 15th February 2013 at 03:20 UTC which may have been a 20-metre diameter near-Earth asteroid.
A fireball was seen over a significant fraction of the United Kingdom and northern Europe on Sunday February 28th at 21:54 UT lasting approximately 3.5 seconds. It was estimated to be a magnitude −9 fireball which generated a sonic boom as it fell. Fragments of the object may have impacted the Earth in the area north of Cheltenham in Gloucestershire. Its solar-system point of origin may lie in the asteroid belt between Mars and Jupiter. It has since been reported that at least part of the carbonaceous chondrite fell at a property in Winchcombe in Gloucestershire making it the first UK-based meteorite find in the past 30 years. The significance of this type of dark stony meteorite lies in the fact that its chemistry is similar to that of the early Solar System.
A loud sonic boom was heard at 14:58 UT on Saturday March 20th 2021. It rattled windows and shook homes for about 20 to 30 seconds and was heard over large tracts of Dorset, Devon, Somerset and Jersey. An explosion, an earthquake, thunder and a sonic boom from an RAF aircraft have all been ruled out. The culprit appears to be a daylight fireball or bolide which may have landed in the Bristol Channel. It has been photographed and may also have been detected on a Eumetsat weather satellite image. To be visible in daylight, the meteor must have been of a significant size, large enough for debris to have reached the ground. Its track through the atmosphere may be revealed by analysis of photographic material.
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 21st 2012 as well as the return of the GOCE satellite just after midnight on Tuesday November 12th 2013.
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 brighter than magnitude +11.0 that may be accessible to observers with binoculars or small telescopes in the northern hemisphere.
Only two comets are brighter than 11th magnitude in the night sky this month. C/2021 O1 Nishimura starts the month at magnitude +9.2 and is likely to brighten somewhat by 0.2 magnitudes by mid-August. It will then fade by half a magnitude in the latter half of the month. C/2021 O1 Nishimura is visible for the first five days of the month in the constellation of Gemini, moving into the neighbouring constellation of Cancer for twelve days and spending the remainder of the month in the constellation of Leo Consequently, it is visible with difficulty with a small, amateur-sized telescope low in the north-eastern sky during the morning twilight during the first half of the August. C/2021 O1 Nishimura was discovered on Wednesday July 21st and reaches perihelion on Thursday August 12th when it is 0.8 au from the Earth.
C/2020 T2 Palomar starts the month at magnitude +10.0 and is likely to fade by half a magnitude during August. It is visible for the first twelve days of the month in the constellation of Virgo and then moves into the neighbouring constellation of Libra for the remainder of August. Consequently, C/2020 the comet is visible with a small, amateur-sized telescope low in the south-western sky during the early evening before it sets. C/2020 T2 Palomar reached perihelion on Sunday July 11th.
Strictly speaking, this phenomenon is an atmospheric one rather than a truly astronomical one. Nonetheless, living in the United Kingdom, we are well placed to see this unusual spectacle during the shorter nights of the summer months, particularly in June and July.
These tenuous cloud-like structures are composed of ice-coated particles at an altitude of around 80 km in the mesosphere, approximately four times higher than the limiting altitude of cirrus cloud. Created by water vapour freezing around meteor smoke in the upper atmosphere, their altitude means that they appear silvery-blue in colour against the darker twilight sky when the Sun lies between 6° and 16° below the horizon.
Noctilucent or 'night shining' Cloud is normally seen between 10° and 20° above the northern horizon exhibiting a range of forms — perhaps the most common is the 'herring-bone' pattern. Normal visibility limits are mid-May to mid-August, peaking around the time of the Summer Solstice. More information, including the facility to report your sightings, can be found at the Noctilucent Cloud Observers' Homepage.
A word of warning; displays are unpredictable and more frequently seen from the northern half of the United Kingdom. Nevertheless, observations have been submitted by observers living in this locality e.g. from Exeter, Castle Cary and Ilminster.
A short animation of a bright noctilucent cloud display observed in the north-western sky from Selsey Bill during the evening twilight on Monday July 15th 2008 by The Sky at Night's Pete Lawrence is worth a look. Another nice animation of a display seen from north west of Calgary, Alberta in Canada on Saturday June 26th is also worth a look. A photograph demonstrating that these clouds can be seen from southern parts of the United Kingdom was taken by David Tate in Castle Cary in the early hours of Monday June 10th 2013.
If you want to look for the International Space Station (ISS) as it passes over Taunton, please have a look at the predictions page on the Heavens Above web site. The ISS is at least as bright as a first magnitude star and can approach the brightness of Venus under favourable conditions. Similarly, if you want to look for the core module of the new, third generation Chinese space station, Tianhe-1, predictions for this 'under-construction' space station can be found on this page. This module, the first of three parts, was launched on Thursday April 29th 2021. Tianhe-1 is significantly fainter than the ISS, normally about as bright as a third of fourth magnitude star. Predictions for other satellites may also be obtained from the Heavens Above web site.
The above image is a 30 minute forecast of the location and probability of auroral activity based loosely on a model developed at Johns Hopkins' Applied Physics Laboratory known as the Ovation Aurora Forecast model. It provides estimates of the energy per unit area on the Earth's atmosphere from observations of the solar wind and interplanetary magnetic field made by the Advanced Composition Explorer satellite in conjunction with empirical relationships derived from the Defense Meteorological Satellite Program. It shows where the aurora is most likely to be seen and how bright it might be. The model generates a global estimate of power, called the Hemispheric Power, deposited into the atmosphere in gigawatts (GW). For powers of less than 20GW, little or no aurora may be visible. For powers of 20-50 GW, you may need to be relatively close to the aurora to see it. For values above 50 GW, the aurora should be easily observable, active and mobile. For values above 100 GW, this is considered to be a significant storm where the aurora may be visible from hundreds of miles away. The current prediction is downloaded when you load this page. If you want to download the latest model, simply reload this page or press F5. If you want to see the full-sized map, please click on the above image.
The above sky chart, generated from the Heavens-Above.com web site, shows what the night sky looks like at 22:00 BST on Monday August 16th 2021 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 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.
In August 2021, the amount of daylight (measured from sunrise to sunset) decreases from 15 hours 20 minutes at the start of the month to 13 hours 36 minutes at the end of the month. Total daylight (sunrise to sunset) for the month is 449 hours 8 minutes.
start and end times of civil, nautical and astronomical twilights.
|h m||h m||h m||h m||h m|
|** ** No phenomenon on that day|
|PLEASE NOTE: These times are in Greenwich Mean Time (GMT) except between 01:00 GMT on March 28th and 01:00 GMT on October 31st when the times are in BST (British Summer Time) which is one hour in advance of GMT.|
The timings in the table above should be accurate to within 1–2 minutes inside the red circle superimposed on the map shown on the left.
Rising and setting times for the Sun, Moon and planets and times of twilights for other locations can be obtained from HMNAO's Websurf web pages using the Rise, Set and Twilight Times option.
The actual times at which the Sun will just appear, or disappear, will depend on the difference between the altitudes of the observer and the local horizon and the actual refraction, which depends on the meteorological conditions along the light path. Differences of a minute or so from the tabulated times are to be expected.
For the drivers amongst you, the 'Hours of Darkness', as defined in the Road Vehicle Lighting Regulations (1989), start half an hour after sunset and end half an hour before the following sunrise. Headlights should be used during the Hours of Darkness and sidelights in the half hour periods after sunset and before sunrise. These timings can also be obtained from HMNAO's Websurf web pages using the Rise, Set and Twilight Times option.
For the pilots amongst you, night, according to Statutory Instrument 2016 No. 765, The Air Navigation Order 2016, Schedule I (Interpretation), Article 2, means 'the time from half an hour after sunset until half an hour before sunrise (both times inclusive), sunset and sunrise being determined at surface level'. In other words, the night time period starts at the beginning of the Hours of Darkness and finishes at the end of the Hours of Darkness. In the United States, the Federal Aviation Administration (Federal Aviation Regulations, Section 1.1) defines night as the time between the end of evening civil twilight and the beginning of morning civil twilight as published in the American Air Almanac, converted to local time. Sunset to the following sunrise can also be defined as night in the United States as well as one hour after sunset to one hour before sunrise. By the way, flying in a total eclipse of the Sun does not count as night flying!