The September equinox heralds the start of astronomical autumn plus we have a total Lunar eclipse that may be tricky to see!
The Sun begins the month in Leo (The Lion) and ends in Virgo (The Maiden) but
comes closer by 1,195,513 km. The highlight of the month, though, is the
Autumnal Equinox which will occur on 22 September at 7:19 pm. On that day,
night and day are equal in time everywhere on Earth and we enter the new season
of astronomical autumn. This will last for 89 days, 20 hours and 43 minutes.
Before that, though, the Sun passes from Leo (The Lion) on 16 September at
12:11 pm and enters Virgo (The Maiden). Daylight shortens from 13:49 (13.818
hours) on 1 September to 11:36 (11.601 hours) on 30 September so we gain 2
hours and 13 minutes of night time, by the end of the month.
The Moon begins the month in Ophiuchus (The Serpent Bearer) and ends in
Sagittarius (The Archer) but comes closer by 7,665 km. Perhaps unusually, the
full Harvest Moon appears first on 7 September at 7:09 pm in Aquarius (The
Water Bearer). Lunar perigee (closest to Earth) on 10 September at 1:19 pm
finds the Moon some 364,756 km away from Earth—around 19,644 km closer than
average—subtending an angle of 32.8 arc-minutes. On 12 September, the rising
Moon will occult and conjunct with the Pleiades, also known as the `Seven
Sisters’, (M45) in Taurus (The Bull). This is followed by last quarter on 14
September at 11:33 am in Taurus (The Bull). The new Moon appears on 21
September at 8:54 pm in Virgo (The Maiden) beginning a new synodic (Lunar)
month which will last 29 days, 16 hours and 31 minutes. Lunar apogee (furthest
from Earth) occurs on 26 September at 10:54 am and takes the Moon to 405,578 km
away from Earth—around 21,178 km further than average—subtending an angle
of 29.5 arc-minutes. On 27 September, the Moon will occult Antares in Scorpio
(The Scorpion) but it will appear in Edinburgh and Lothian as a conjunction at
low altitude. Finally, the first quarter of the new Lunar cycle shows up on 30
September at 12:54 am in Sagittarius (The Archer).
There is a total Lunar eclipse on 7 September but viewing is difficult due to
civil twilight and the low altitude of the Moon. The maximum for Edinburgh and
Lothian occurs within minutes of moonrise and the eclipse will formally end
(after partial and penumbral phases) at 9:55 pm. The total duration will be
2 hours and 7 minutes in our location.
For the inferior planets: Mercury begins the month in Leo (The Lion) and ends
in Virgo (The Maiden) but recedes by 21,793,072 km. The Swift Planet' reaches superior conjunction on 13 September and, so, is lost in the Sun's glare. This also marks the moment when it transitions from being a morning object to an evening object for keen observers. Mercury will be furthest from Earth on 20 September and decreases in magnitude from -1.35 to -0.52 (2.17 times in brightness) over the whole month. Venus begins the month in Cancer (The Crab) and ends in Leo (The Lion) and, also, recedes by 22,283,948 km but the brightness remains stable at -3.93 magnitudes. Venus is, very much, the Morning Star’ planet in September.
For the superior planets: Mars remains in Virgo (The Maiden) all month but
recedes by 14,010,156 km. The Red Planet' increases in magnitude from 1.62 to 1.57 (1.05 times in brightness) over the month. Jupiter remains in Gemini (The Twins) but comes closer by 61,024,864 km. As such, theGas Giant’ increases in
magnitude from -1.99 to -2.12 (1.13 times in brightness) during September.
Saturn remains in Pisces (The Fishes) but comes closer by 7,164,590 km. TheRinged Planet' will be 4 degrees south of the waning gibbous Moon on 8 September in the evening with Neptune between the two. Saturn will reach opposition on 21 September and be closest to Earth all year. Around and after midnight is an excellent time to view the rings which are re-emerging from edge-on. Uranus remains in Taurus (The Bull) all month long but comes closer by 69,883,590 km. Consequently, theGreen Planet’ increases in magnitude from 5.72 to 5.66 (1.05
times in brightness). Uranus will reach a stationary point on 6 September when
the planet turns to a retrograde orbital path. Neptune remains in Pisces (The
Fishes) all month but comes closer by 8,807,197 km. The `Blue Giant’ will reach
opposition on 23 September and will be closest to the Earth all year.
There is a meteor shower visible in September but, occurring just 2 days after
the full Moon, it will be difficult to see. The epsilon-Perseids (208 SPE)
peak overnight on 9/10 September with, perhaps, 8 shooting stars per hour. The
radiant point is near Algol (the `Demon Star’). The parent body is unknown.
At the time of our sky map, some constellations visible are Cygnus (The Swan)
at zenith, Lynx (The Lynx) in the north, Andromeda (The Chained Maiden) in the
east, Corona Borealis (The Northern Crown) in the west (which contains our
elusive recurrent nova known as the Blaze star) and Aquila (The Eagle) in the
south. The ecliptic hosts Taurus (The Bull), Aries (The Ram), Pisces (The
Fishes), Aquarius (The Water Bearer), Capricorn (The Sea Goat) and Sagittarius
(The Archer).
The `Summer Triangle’—Vega in Lyra (The Lyre), Altair in Aquila (The Eagle)
and Deneb in Cygnus (The Swan)—is prominent in the south. Also, highly
visible in the east is the great square of Pegasus (The Winged Horse) with the
sentinel stars Scheat, Alpheratz, Algenib and Markab. Circumpolar
constellations—always above the horizon—include Camelopardalis (The
Giraffe), Cassiopeia (The Seated Queen), Draco (The Dragon) and Ursa Major (The
Great Bear).
