SEPTEMBER 2020

September 2020

The Sun begins the month in the constellation of Leo, but on the 16^th at 13h00, crosses the astronomical border which separates Leo from Virgo, in which constellation it remains till the month ends.

The Autumnal Equinox on Sept 22d at 13h31 marks the official start of Autumn. Day and night are almost equal in length again, and in the northern hemisphere, autumn lasts for 89.85 days. The Earth-Sun distance at this time is 150 125 903 km.

September is the best month to observe the ethereal Zodiacal Light during the early mornings when the Moon is not present in the sky, and you are well away from light pollution. Look towards the east before the onset of morning twilight, around 03h30, and you should see a faint cone of light pointing southwards at a steep angle of 60°. This phenomenon is caused by the Sun illuminating the disc of fine dust, which is the remnant of solar system formation 4.5 thousand million years ago. The best days to observe this morning cone are from Sept 17^th to the end of the month.

The Moon

The Moon is at apogee, its farthest from the Earth, on the 6^th at around 06h (diameter of the moon 29’ of arc) and at perigee (nearest to the Earth) at 14h00 on the 18^th (diameter of the moon 33 mins of arc).

Full Moon at 05h23 on the 2^nd, is in the  ‘water jug’ of Aquarius,. This Moon is called the “Harvest Moon”, since, before the days of mechanisation, harvest was a long process and the labourers would have to work well into the night. For several nights before and after Full, the Moon rises at about the same time each evening as the sun sets and so its light enabled the harvesters to continue their labours into the night. Look for the Harvest Moon rising almost due east at sunset at this time.

Last Quarter Moon is at 09h26 on the 10^th in the constellation of Taurus, between the ‘horns of the Bull’. This is one of the highest LQ Moons of the year.

New Moon is on the 17^th at 11h01, on the Leo/Virgo border, passing 5° above the Sun.

First Quarter Moon takes place at 01h56 on the 24^th, in Sagittarius, and is one of the lowest FQ Moon of the year.

Earthshine may be seen on the dark hemisphere of the waning crescent Moon from the 11^th to the 16^th, and it may also be glimpsed on the night hemisphere of the waxing crescent from the 18^th to the 22^nd.

The Planets

Mercury is too close to the Sun in the evening sky to be observed during the whole of September.

Venus is the brightest ‘stellar’ object in the morning sky, rising between 01h and 02h throughout September. The planet’s visual magnitude is -4.2, and through a telescope exhibits a gibbous phase. It lies at a distance of just less than 1 astronomical unit (the mean Sun-Earth distance). The waning crescent Moon with earthshine is in conjunction with Venus during the morning of the 14^th, when the two are almost 4°apart. This takes place in the constellation of Cancer the Crab, with the beautiful Praesepe cluster, M44, between the two. The star just to the north of the Moon is Ascellus Borealis (Northern Ass), and the star just 1° to the upper left of Venus is Ascellus Australis (the Southern Ass)

Mars grows brighter as the month progresses as it heads towards its opposition on October 13^th. The planet’s visual magnitude increases from -2.0 to -2.5. The ‘Red Planet’ is a conspicuous object in the September night sky, rising soon after sunset in the western part of the constellation of Pisces, where it stays till after opposition. The planet has an angular diameter of around 21 secs of arc during September. During the morning of the 6^th, there is a beautiful close conjunction between the waning gibbous Moon and Mars. The planet lies less than a degree to the north of the Moon, and this will give astrophotographers to capture the two on a single image. The sight of the two together in the sky will be spectacular to the unaided eye and in binoculars. From the Mediterranean and North Africa, including Turkey, southern Greece, Cyprus, Malta, Sicily, southern Italy, southern Spain and southern Portugal, an occultation of the planet by the Moon may be observed.

During September, Jupiter is an evening object, setting at midnight as the month begins and at 22h00 at the end of the month. It lies in the constellation of Sagittarius and so never attains a great altitude as seen from the UK. Saturn lies some 8° to the east of Jupiter and of theoretical interest, the planet lies between these two major planets. Jupiter’s visual magnitude is -2.4 during the month. The Moon, just after first quarter may be seen approaching Jupiter on the evening of the 24^th; on that evening Jupiter lies 6° to the upper left of the Moon. Take the opportunity to observe the Galilean satellites; Io, Europa, Ganymede and Callisto as the configuration changes on a nightly basis. Identification of the satellites is to be found on the Front Page of the Sky Notes.

As mentioned above, both Jupiter and Saturn, arein the constellation of Sagittarius; however Saturn is much fainter than Jupiter, with a visual magnitude of +0.4. Saturn and the Moon are in conjunction in the evening of the 25^th, when at 21h Saturn is 3.5° north of the waxing gibbous Moon.

Uranus at magnitude +5.69 lies in Aries is visible most of the night. Through an astronomical telescope has the appearance of a tiny greyish green disc. Uranus lies just over 10° to the south of Hamal, the constellation’s brightest star. See the Remote Planets page to find its position. 

Neptune comes into opposition and its nearest to the earth on the evening of the 11^th.  It lies in the constellation of Aquarius, just south of the Pisces border. The planet’s magnitude is +7.83, too faint to be seen by the unaided eye, but visible in binoculars less than a moon-width to the lower left of the +5.5 magnitude star 96 Aquarii as a bluish point of light

In order to locate this remote planet, you are encouraged to visit the Remote Planets page accessible via the MENU above. The planet is visible all night and culminates (crosses the south meridian) around midnight at an altitude of 29°.

Constellations visible in the south around midnight, mid-month, are as follows: Aquarius, the western fish of Pisces, sometimes known as ‘The Circlet’ because of its shape, and the large autumn square of Pegasus. Almost overhead are the great galaxy in Andromeda and the ‘W’ shaped constellation of Cassiopeia.

All times are GMT     1° is one finger width at arm’s length.

SUMMARY

The phenomena of the month : SEPTEMBER, 2020

Times are given in UT for SCARBOROUGH (0° 25' 0" W, 54° 16' 3" N, zone 0 = UT).

Date        Hour    Description of the phenomenon

yyyy mm dd  hh:mm

2020 09 02 05:22 FULL MOON

2020 09 02 11:05 Minimum of the variable star Algol (beta Persei)
2020 09 03 02:26 Close encounter between the Moon and Neptune (topocentric dist. centre to centre = 4.6°)
2020 09 04 04:49 Maximum of the variable star delta Cephei
2020 09 04 11:43 Minimum of the variable star beta Lyrae
2020 09 05 07:53 Minimum of the variable star Algol (beta Persei)
2020 09 06 05:59 Close encounter between the Moon and Mars (topocentric dist. centre to centre = 0.4°)
2020 09 06 06:31 Moon at apogee (geocentric dist. = 405607 km)
2020 09 07 07:47 Close encounter between the Moon and Uranus (topocentric dist. centre to centre = 3.5°)
2020 09 07 15:11 Maximum of the variable star eta Aquilae
2020 09 08 04:42 Minimum of the variable star Algol (beta Persei)
2020 09 08 23:31 Meteor shower : Sept. Perseids (5 meteors/hour at zenith; duration = 16.0 days)
2020 09 09 04:24 Maximum of the variable star zeta Gemini
2020 09 09 13:36 Maximum of the variable star delta Cephei
2020 09 10 09:26 LAST QUARTER OF THE MOON
2020 09 11 01:31 Minimum of the variable star Algol (beta Persei)
2020 09 11 02:27 Opposition of the asteroid 22 Kalliope with the Sun (dist. to the Sun = 2.801 AU; magn. = 10.5)
2020 09 11 14:34 Opposition of the asteroid 19 Fortuna with the Sun (dist. to the Sun = 2.137 AU; magn. = 9.2)
2020 09 11 20:26 OPPOSITION of Neptune with the Sun
2020 09 13 04:20 Close encounter between the Moon and Pollux (topocentric dist. centre to centre = 4.8°)
2020 09 13 05:58 Close encounter between Venus and M 44 (topocentric dist. centre to centre = 2.5°)
2020 09 13 22:19 Minimum of the variable star Algol (beta Persei)
2020 09 14 02:58 Close encounter between the Moon and M 44 (topocentric dist. centre to centre = 1.2°)
2020 09 14 04:33 Close encounter between the Moon and Venus (topocentric dist. centre to centre = 3.8°)
2020 09 14 19:26 Maximum of the variable star eta Aquilae
2020 09 14 22:23 Maximum of the variable star delta Cephei
2020 09 16 19:08 Minimum of the variable star Algol (beta Persei)
2020 09 17 10:17 Minimum of the variable star beta Lyrae
2020 09 17 10:59 NEW MOON
2020 09 18 13:44 Moon at perigee (geocentric dist. = 359082 km)
2020 09 19 01:10 Close encounter between the Moon and Mercury (topocentric dist. centre to centre = 5.2°)
2020 09 19 03:00 Mercury at its aphelion (distance to the Sun = 0.46670 AU)
2020 09 19 07:59 Maximum of the variable star zeta Gemini
2020 09 19 15:56 Minimum of the variable star Algol (beta Persei)
2020 09 20 07:11 Maximum of the variable star delta Cephei
2020 09 21 23:41 Maximum of the variable star eta Aquilae
2020 09 22 11:29 Close encounter between Mercury and Spica (topocentric dist. centre to centre = 0.3°)
2020 09 22 12:45 Minimum of the variable star Algol (beta Persei)
2020 09 22 13:30 AUTUMN EQUINOX
2020 09 24 01:55 FIRST QUARTER OF THE MOON
2020 09 25 06:59 Close encounter between the Moon and Jupiter (topocentric dist. centre to centre = 2.1°)
2020 09 25 09:34 Minimum of the variable star Algol (beta Persei)
2020 09 25 14:43 Close encounter between the Moon and Pluto (topocentric dist. centre to centre = 2.1°)
2020 09 25 15:58 Maximum of the variable star delta Cephei
2020 09 25 22:46 Close encounter between the Moon and Saturn (topocentric dist. centre to centre = 3.1°)
2020 09 27 21:13 Beginning of occultation of 39-epsilon Cap (magn. = 4.51)
2020 09 27 22:29 End of occultation of 39-epsilon Cap (magn. = 4.51)
2020 09 28 00:45 Beginning of occultation of 43-kappa Cap (magn. = 4.72)
2020 09 28 06:22 Minimum of the variable star Algol (beta Persei)
2020 09 29 03:56 Maximum of the variable star eta Aquilae
2020 09 29 11:33 Maximum of the variable star zeta Gemini
2020 09 30 06:22 Close encounter between the Moon and Neptune (topocentric dist. centre to centre = 4.3°)
2020 09 30 07:48 Opposition of the asteroid 68 Leto with the Sun (dist. to the Sun = 2.283 AU; magn. = 9.5)
2020 09 30 08:53 Minimum of the variable star beta Lyrae
2020 09 30 23:40 Beginning of occultation of 30 Psc (magn. = 4.37)
2020 10 01 00:55 End of occultation of 30 Psc (magn. = 4.37)

Calculations courtesy of: CoelixApex software.