This page provides some astronomical information on a monthly basis for those of you living in the Taunton area. Timings are in GMT (Greenwich Mean Time) unless otherwise noted. Latest additions or updates are highlighted with a red border.
This month we have sections on:
Clocks in the United Kingdom and the rest of the European Union go forward one hour on the last Sunday in March under the provisions of Directive 2000/84/EC of the European Parliament and of the Council. Consequently, on March 29th at 01:00 GMT (Greenwich Mean Time) clocks are moved forward to 02:00 BST (British Summer Time). Any event listed here taking place after 02:00 BST on March 29th will be given in terms of British Summer Time.
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.
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 Tuesday, 2020 March 31 at 10:02:38 BST.
On this day, the Sun crosses the celestial equator moving northwards and the approximate length of night and day are the same. The word "equinox" is derived from the Latin words "aequus" meaning equal and "nox" meaning night. The number of daylight hours will continue to increase until we reach the maximum amount of daylight at the northern hemisphere Summer Solstice on Saturday June 20th at 22:44 BST. Please click on the image above to see a larger version of the diagram demonstrating the occurrence of solstices and equinoxes.
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.
A new, small active region is about to appear over the north-eastern limb of the Sun bringing the previous nineteen-day spotless run to an end. Given its high latitude and magnetic signature, it is a member of the new Solar Cycle 25. The total number of spotless days for 2020 remains at sixty nine, or 76% of the year so far. Solar winds are currently blowing with velocities of around 490 km/s and the planetary Kp geomagnetic activity index is likely to peak at 4 (unsettled) today. A new coronal hole close to the centre of the Earth-facing disk of the Sun has appeared. Solar winds emanating from this feature could reach the Earth on April 3rd–4th. Overall solar activity remains at very low levels.
The increasing number of spotless days heralds the coming of the solar minimum expected in 2019/2020. The decline in the number of sunspots is greater than expected. This could be the deepest solar minimum in more than a century. This 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. A new satellite has been launched, TSIS-1, which will monitor the Sun over the next five years covering the whole of the upcoming 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 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.
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 this solar maximum is more complex than had been previously predicted. The maximum is 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 are significantly down on the predictions made for this maximum — indeed solar cycle 24 may be the weakest in the last 100 years or so i.e. since solar cycle 14. Assuming the start of 2014 was the beginning of the post maximum phase of solar cycle 24, we are now well into the declining phase of activity where 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 be expected from this type of violent outburst. The next solar minimum, characterized by periods of many days without sunspots and flare activity, is likely to occur between July 2019 and September 2020. 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 next solar maximum is expected to occur between 2023 and 2026. Solar cycle 25 is likely to be similar to solar cycle 24 which means another weak maximum and a long, deep minimum.
The sequence of Moon phases for this month and their designations are shown in the following animation:
|Moon phases for March 2020 are as follows:|
|First Quarter||—||Monday March 2nd at 19:57 GMT|
|Full Moon||—||Monday March 9th at 17:48 GMT
"Worm Moon" / Supermoon
|Last Quarter||—||Monday March 16th at 09:34 GMT|
|New Moon||—||Tuesday March 24th at 09:28 GMT
The Moon is at perigee (i.e. closest to the Earth) on Tuesday March 10th at 06:30 GMT when it is 357,122 km from the Earth. It is at apogee (i.e. furthest from the Earth) on Tuesday March 24th at 15:23 GMT when it is 406,692 km from the Earth.
On Wednesday March 18th, the Moon occults the planet Mars which lies in the constellation of Sagittarius. This occultation by the waning crescent moon is visible from the southernmost parts of South America, the Falkland Islands, South Georgia, Antarctica and the Kerguelen Islands. 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.
The term 'Supermoon' was coined in 1979 by astrologer Richard Nolle. He defined it as "a new or full moon which occurs with the moon at or near (within 90 percent of) its closest approach to Earth in a given orbit", without explaining why the 90 percent figure was chosen. As the Moon's orbit is elliptical, not circular, there is a point in its orbit where it is closest to the Earth (perigee) and another one where it is furthest away from the Earth (apogee) and these perigee and apogee distances change somewhat from one orbit to another. In the period between 1850 and 2050, perigee distances for the Moon range from 356,375 km to 370,355 km while apogee distances range from 404,055 km to 406,710 km. Using Nolle's criterion, on average, a full moon occurring within 367,607 km of the Earth will be a supermoon.
The closest full moons occur on average in cycles of just over a year as 14 lunar months or lunations is only 2.7 hours longer than the time taken for 15 returns to perigee. The full moon of 2020 February 9th takes place at a distance of 362,477 km, nearly 37 hours before perigee. The next full moon of March 9th takes place at a distance of 357,400 km, less than 13 hours before perigee. The full moon on April 8th takes place at a distance of 357,030 km, just over 8 hours after perigee. The full moon on May 7th takes place at a distance of 361,183 km, less than 32 hours before perigee. The February and May full moons are marginal supermoons and, by some, may not be classed as supermoons. The full moons within this four month period of 2020 all take place at distances of less than 362,500 km from the Earth. We might say that the supermoon of April 8th is more super than the other three supermoons as it takes place at a distance of only 357,035 km from the Earth. However, it does not make the list of the fifteen closest full moons in the interval 1850–2050 given below.
|The Fifteen Closest Full Moons: 1850–2050|
The four closest full moons in the 21st century will take place on 2034 November 25th at 22:32 UT at a distance of 356,446 km, 2052 December 6th at 07:18 UT at a distance of 356,426 km, 2070 December 17th at 16:05 UT at a distance of 356,463 km and 2098 January 17th at 10:36 UT at a distance of 356,461 km. Perhaps these will be known as 'Ultimoons'!
Many media articles will mention that the Moon will be 14% bigger and 30% brighter than when the full moon occurs furthest from the Earth or 7% bigger and 15% brighter than average. A nice illustration of this can be seen on the Astronomy Picture of the Day site. As a result of these differences, you might expect to see a significantly bigger and brighter Moon but this is not the case. The transition between an apogee full moon and a perigee full moon takes place over seven lunar cycles so the apparent changes in size from one full moon to the next are only perhaps 2% in apparent size and 3% in apparent brightness. These changes are more difficult to detect. Indeed, discerning changes in the size of the Moon is even more difficult to perceive when the Moon is close to the horizon due to the so-called 'Moon Illusion'. On a given night, the rising or setting Moon will appear larger than when it is high in sky. There is no proper explanation for this perceived difference but it may be related to the presence of perceptual cues for the eye near the horizon which are missing for an object much higher in the sky.
Is the supermoon just another piece of media hype? Have you also noticed the increasing use of the term 'Micromoon' for the smallest full moon in a given period of time? Neil de Grasse Tyson, the director of the Hayden Planetarium in New York, has suggested that supermoons are indeed over-hyped. "I don't know who first called it a Supermoon" he told StarTalk radio. "I don't know, but if you have a 16-inch pizza, would you call that a super pizza compared with a 15-inch pizza?". Enough said ...
There are six eclipses visible during 2020, four penumbral eclipses of the Moon and one annular and one total eclipse of the Sun. Parts of three of the penumbral eclipses of the Moon are visible from the United Kingdom, only one is visible in its entirety. Neither of the solar eclipse are visible from the United Kingdom.
A penumbral eclipse of the Moon occurred on Friday January 10th 2020. It was visible in its entirety from northern Alaska, Asia, the Philippines, Indonesia, western Australia, the Middle East, Madagascar, Africa except eastern parts, Europe including the United Kingdom, Iceland and most of Greenland. Parts of the eclipse were visible from north-western parts of North America, most of Australia, eastern parts of Africa and north-eastern parts of Canada. This was a deep penumbral eclipse with a magnitude of 0.921, making it somewhat easier to discern. From Taunton, the whole eclipse was visible starting about an hour after moonrise at 17:06 UT and ending at 21:14 UT.
A penumbral eclipse of the Moon occurs on Friday June 5th 2020. It is visible in its entirety from most of Australia except the north-eastern part, the Philippines, Indonesia, south-east Asia, most of China except the north-eastern part, central Asia, India, the Middle East, Madagascar and Africa except the north-west part. Parts of the eclipse are visible from New Zealand, Japan, northern Asia, Europe including the United Kingdom, north-western Africa and easternmost parts of South America. This is a modest penumbral eclipse with a magnitude of 0.593, making it difficult to discern. From Taunton, the eclipse starts at moonrise at 21:12 BST and ends at 22:07 BST.
An annular eclipse of the Sun occurs on Sunday June 21st 2020. It is visible in its entirety from most of the eastern half of Africa, the northern half of Madagascar, south-east Europe, most of Asia except the northernmost part, westernmost parts of Micronesia and Melanesia, Papua New Guinea and northernmost parts of Australia. The path of annularity begins over the north-eastern part of the Republic of the Congo and crosses the north-western part of the Democratic Republic of Congo, the south-eastern tip of the Central African Republic, South Sudan, northern Ethiopia, central Eritrea, Yemen, the south-eastern tip of Saudi Arabia, north-eastern Oman, Pakistan, the northernmost part of India, Tibet, southern China, Taiwan and ends south-east of Guam in the Northern Mariana Islands. The eclipse is not visible from the United Kingdom.
A penumbral eclipse of the Moon occurs on Sunday July 5th 2020. It is visible in its entirety from westernmost parts of Africa and the Americas with the exception of north-western parts of North America. Parts of the eclipse are visible from Madagascar, most of Africa, western Europe including the United Kingdom, the southernmost part of Greenland and north-western parts of the United States, central Canada, eastern Polynesia and New Zealand. From Taunton, the shallow penumbral eclipse starts at 04:04 BST and ends at moonset at 05:01 BST. It will be a difficult eclipse to detect with the naked eye.
A penumbral eclipse of the Moon occurs on Monday November 30th 2020. It is visible in its entirety from Greenland, North America, Polynesia, the North Island of New Zealand, northern Japan and Siberia. Parts of the eclipse are visible from Scandinavia, the United Kingdom, the Caribbean region, South America, the South Island of New Zealand, Australia, south east Asia and central Asia. From Taunton, the reasonably deep penumbral eclipse starts at 07:30 UT and ends at moonset at 07:48 UT. The depth of the eclipse will make it easier to discern.
A total eclipse of the Sun occurs on Monday December 14th 2020. It is visible in its entirety from the south-eastern part of the Pacific basin including French Polynesia, most of South America except the northern part, parts of Antarctica, the South Atlantic Ocean and the south-western part of Africa. The path of totality begins over the north-eastern part of French Polynesia and passes over the south-eastern Pacific Ocean and then crosses the central part of Chile and Argentina, passing over the South Atlantic Ocean and ends just off the coast of central Namibia. The eclipse is not visible from the United Kingdom.
Further information on all the eclipses in 2020 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, 2021, are also available.
Mercury reappears very low in the eastern morning twilight sky at the end of the first week of March. It is at magnitude +1.6 at the start of the first week of the month when it rises in the east south-eastern sky around an hour after the Sun. Mercury brightens to 0.0 by the end of March when it rises in the eastern sky less than an hour after the Sun. It lies 4° north of the waning crescent moon on Saturday March 21st and reaches greatest western elongation on Tuesday March 24th.
Venus is unmistakable in the western evening twilight sky setting in the late evening about about four hours after the Sun. It continues to gain altitude during March and brightens somewhat from magnitude −4.3 at the start of the month to magnitude −4.5 at the end of March. Venus lies 2.0° north of Uranus on Monday March 9th, reaches greatest eastern elongation on Tuesday March 24th and lies 7° north of the waning crescent Moon on Saturday March 28th.
Mars is visible in the south-eastern morning twilight sky, rising just over two hours before the Sun and setting around after mid-day. It spends all but the last day of March in the constellation of Sagittarius before moving into Capricornus. Mars brightens somewhat from magnitude +1.1 at the start of the month to +0.8 at the end of March. It lies 0.7° north of the waning crescent moon on Wednesday March 18th which can be seen as an occultation in certain parts of the world. Mars lies 0.7° south of Jupiter on Friday March 20th and 0.9° south of Saturn on Tuesday March 31st.
Jupiter is visible in the south-eastern morning twilight sky rising between two and three hours before the Sun. It lies in the constellation of Sagittarius for the remainder of the year brightening slightly from magnitude −2.0 to magnitude −2.1 during March. Jupiter lies 1.5° north of the waning crescent moon on Wednesday March 18th and 0.7° north of Mars on Friday March 20th.
Saturn is visible in the south-eastern morning twilight sky rising between one and half and two and a half hours before the Sun. It lies in the constellation of Sagittarius for the first three weeks of March moving into Capricornus for the rest of March. Saturn remains at magnitude +0.7 for the whole of March. It lies 2.0° north of the waning crescent moon on Thursday March 19th and lies 0.9° north of Mars on Tuesday March 31st.
Uranus rises in the east north-eastern sky after sunrise and sets in the late evening in the west north-western sky. It is a blue-green object which fades slightly from magnitude +5.8 at the start of the month to +5.9 at the end of March. Uranus lies in the south-western part of the constellation of Aries approximately 6.4° north east of the fourth magnitude star Omicron Piscium. This planet can also be glimpsed with the naked eye under optimum conditions.
Neptune is too close to the Sun to observe during March. It lies in the north-eastern part of the constellation of Aquarius where it will remain for the rest of the year, currently lying approximately 6.8° to the north east of the third magnitude star Lambda Aquarii. Neptune is a bluish object of +8.0 during March. 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.
Pluto rises an hour to two hours before sunrise in the south-eastern morning twilight sky between Saturn and Jupiter. It lies in the north-eastern part of the constellation of Sagittarius about 5.0° to the south west of Saturn in mid-March. 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.
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 twilight itself. In the photograph, the Zodiacal Light is on the left and the Milky Way is on the right. For Taunton, astronomical twilight ends in the evening at around 19:45 GMT at the beginning of the month and at around 20:40 GMT (21:40 BST) 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.
There are no major meteor showers active during March. The next significant shower is the April Lyrids, active during the latter half of April and peaking on Wednesday April 22nd at around 07:00 UT. The radiant lies close to the first magnitude star Vega with the shower displaying a rate of about 20 meteors per hour although this can occasionally reach 90 meteors per hour for short periods. The peak usually lasts about fifteen hours. This year's display is very well-aspected as the maximum occurs just before new moon. The shower usually produces meteors with magnitudes of around +0.2. However, some meteors known as 'Lyrid fireballs' can cast shadows for a second or so and leave behind smokey debris trails lasting minutes. Further information 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 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 2013 February 15th 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 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 that may be accessible to observers with binoculars or small telescopes in the northern hemisphere.
C/2017 T2 (PANSTARRS) starts the month as a magnitude 8.8 object visible with a small telescope in the constellation of Cassiopeia where it remains for the whole month. It is circumpolar so it is visible throughout the night but it is highest in the sky in the early part of the night. It should reach magnitude 8.4 by the end of March and will reach perihelion on Monday May 4th 2020 by which time it may become a magnitude 8.2 object.
C/2019 Y1 (ATLAS) is visible with a small telescope low in the north-western evening twilight sky for the first half of the month in the Great Square of Pegasus. It is a magnitude 9.7 object which will brighten by about 0.4 magnitudes by the end of March. It spends the second half of the month in the constellation of Andromeda.
C/2019 Y4 (ATLAS) is visible with a small telescope or binoculars high in the evening sky in Ursa Major. In mid-February this comet unexpectedly brightened by about five magnitudes – at the start of March it was a magnitude 12.5 object. Since then it has undergone another surge in brightness and is currently magnitude 8.0 as of mid-March. Between early February and mid-March it has exhibited a 4000-fold increase in brightness leading to a wide range estimates as to how bright this comet might get. It may also be vaporised by the Sun as it approaches perihelion on Saturday May 30th. By the end of March, it will have crossed into the neighbouring constellation of Camelopardalis and could be visible to the naked eye in early April. Magnitude estimates for May lie in the range +1 to −5. If it becomes as bright as Venus, it may be visible in daylight – something that has not happened since C/2006 P1 McNaught on 13–14 January 2007.
If you want to look for the International Space Station (ISS) as it passes over Taunton, please have a look at this 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. Similarly, if you want to look for the Chinese space station, Tiangong-1, you are too late! Tiangong-1 re-entered the Earth's atmosphere in an 'uncontrolled manner' on April 2nd 2018 at 00:16 UTC over an uninhabited part of the central Pacific Ocean at longitude 164.3° west and 13.6° south after the loss of a telemetry link in 2016. Information for Tiangong-2, the sole remaining Chinese space station orbiting the Earth, can be found on this page. Tiangong-2 is significantly fainter than the ISS, normally as bright as a third or fourth magnitude star. Predictions for other satellites may also be obtained from the Heavens Above web site.
Another satellite-related phenomena to look out for are the so-called 'Iridium flares'. These bright flashes of sunlight reflecting off the Iridium series of communication satellites can be seen at night and also occasionally during the daytime if they are bright enough. Predictions for the next seven nights are available.
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 20-50GW, you may need to be relatively close to the aurora to see it. For values above 50GW, the aurora should be easily observable, active and mobile. For values above 100GW, 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 GMT on Monday March 16th 2020 from Taunton. The night sky will look the same an hour later at 23:00 GMT at the beginning of the month and an hour earlier at 21:00 GMT (22:00 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 March 2020, the amount of daylight (measured from sunrise to sunset) increases from 10 hours 58 minutes at the start of the month to 12 hours 54 minutes at the end of the month. Total daylight (sunrise to sunset) for the month is 370 hours 0 minutes.
start and end times of civil, nautical and astronomical twilights.
|h m||h m||h m||h m||h m|
|** ** No phenomenon that day|
|PLEASE NOTE: These times are in Greenwich Mean Time (GMT) except between 01:00 GMT on March 29th and 01:00 GMT on October 25th when the times are in BST (British Summer Time) which is one hour in advance of GMT. Times given in red are in BST.|
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 VFR (Visual Flight Rules) pilots amongst you, night, according to Statutory Instrument 2009 No. 3015, Civil Aviation, The Air Navigation Order 2009, Part 33 (Interpretation), Article 255(1), 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.