The Lyrid meteor shower lights up the April sky but we cannot see the new supermoon.
The Sun leaves Pisces (The Fishes) on 18 April at 6:23 pm and enters Aries
(The Ram) and recedes from Earth by 1,238,923 km. Daylight lengthens from
13:07 (13.121 hours) on 1 April to 15:18 (15.307 hours) on 30 April so we
lose 2 hours and 11 minutes of night time by the end of April.
Observational astronomy becomes more difficult for the next several months
as we head towards a night sky consisting of perpetual astronomical
twilight. Prime astronomical dark time amounts to 6 hours 17 minutes at
the start of April and reduces to 1 hour 55 minutes by the end of April.
The Moon begins and ends April in Virgo (The Maiden) and recedes by 10,431
km. The full Pink Moon begins the month on 2 April at 3:12 am in Virgo
(The Maiden). Lunar apogee (furthest from Earth) occurs on 7 April at 9:27
am and takes the Moon to 404,935 km away from Earth—around 20,535 km
further than average—subtending an angle of 29.5 arc-minutes. The Moon
enters last quarter on 10 April at 5:52 am in Sagittarius (The Archer).
The new Moon appears on 17 April at 12:52 pm in Pisces (The Fishes)
beginning a new synodic month which will last 29 days, 8 hours and 9
minutes. Since this is a ‘perigee syzygy’, it makes it a supermoon
but—because it is new—it cannot be seen! Lunar perigee (closest to
Earth) occurs on 19 April at 7:50 am and finds the Moon some 361,646 km
away from Earth—around 22,754 km closer than average—subtending an
angle of 33.0 arc-minutes. The first quarter Moon shows up on 24 April at
3:32 am in Cancer (The Crab).
The waning gibbous Moon conjuncts with Spica in Virgo (The Maiden) in the
early hours of 3 April. Regulus in Leo (The Lion) conjuncts and is
occulted by the waxing gibbous Moon in the darkest hours of 26 April.
For the inferior planets: Mercury begins the month in Aquarius (The Water
Bearer) and ends in Pisces (The Fishes) but recedes by 61,116,092 km
(0.409 AU). Mercury increases in magnitude from 0.44 to -0.79 (3.10 times
in brightness) over the month. The ‘Swift Planet’ reaches dichotomy, where
exactly half the surface is illuminated by sunlight, and greatest western
elongation on 3 April. Aphelion, furthest from the Sun, occurs the
following day. Venus begins the month in Aries (The Ram) and ends in
Taurus (The Bull) but approaches by 19,574,419 km (0.131 AU). It shines
brightly at -3.92 magnitudes all month and rises higher as the month
progresses earning it’s epithet of the ‘Evening Star’ planet. On 19 April,
Venus in Taurus (The Bull) will be 4.8 degrees south of the waxing crescent
Moon in Aries (The Ram) in the morning. The Sun will be up, of course, but
the Moon and Venus are the next 2 brightest objects in the sky so they may
be visible.
For the superior planets: Mars begins the month in Aquarius (The Water
Bearer) and ends in Pisces (The Fishes) but approaches by 7,420,213 km
(0.050 AU). The ‘Red Planet’ decreases in magnitude from 1.18 to 1.23
(1.04 times in brightness) over the month. Jupiter remains in Gemini (The
Twins) all month and recedes by 70,829,820 km (0.473 AU). The ‘Gas Giant’
decreases in magnitude from -2.20 to -2.01 (1.19 times in brightness) over
the month. Jupiter reaches eastern quadrature on 5 April making the angle
between planet, Earth and the Sun exactly 90 degrees. On 22, Jupiter will be
3.6 degrees south of the waxing crescent Moon in the late evening.
Saturn begins the month in Pisces (The Fishes) and ends on the border of
Pisces and Cetus (The Sea Monster) and approaches by 23,696,817 km (0.158
AU) but this barely affects the brightness of 0.92 magnitudes. Uranus
remains in Taurus (The Bull) all month but recedes by 41,742,574 km (0.279
AU) and maintains a steady 5.81 magnitudes. Neptune remains in Pisces (The
Fishes) all month but approaches by 28,762,987 km (0.192 AU). It, too,
remains steady at 7.8 magnitudes.
You may see some sensational claims about a 4 planet conjunction between
18–20 April featuring Neptune, Mars, Saturn and Mercury. They do form a
tight group in the dawn twilit sky but don’t be fooled for they are low on
the horizon and sure to be photobombed by the rapidly rising Sun!
Shooting star watchers may enjoy the Lyrid meteor shower (006 LYR) between
14–30 April and peaking on the night of 22 April. Since the radiant point
is circumpolar, they are visible all night after sunset near the bright
star Vega in Lyra (The Lyre). The zenith hourly rate (ZHR) is a decent 18
and the Moon phase is waxing crescent with 34% illumination. Seeded by
(C/1861 G1) Thatcher’s Comet, these are the oldest meteor showers having
been observed by Chinese astronomers in 687 BCE. Thatcher’s comet has a
period of around 415 years and will not be visible in our night sky until
it returns to perihelion sometime in 2276.
At the time of our sky map, some constellations visible are Ursa Major
(The Greater Bear) at zenith, Cepheus (The King) in the north, Serpens
(The Serpent) in the east, Auriga (The Charioteer) in the west, and Crater
(The Cup) in the south. The ecliptic hosts Virgo (The Maiden), Leo (The
Lion), Cancer (the Crab), Gemini (The Twins), Taurus (The Bull) and Aries
(The Ram).
In April, we witness three pseudo-constellations known as triangles.
The ‘Winter Triangle’—Procyon in Canis Minor (The Lesser Dog), Sirius in
Canis Major (The Greater Dog) and Betelgeuse in Orion (The Hunter)—sets
in the late evening in the west. The ‘Summer Triangle’—Deneb in Cygnus
(The Swan), Vega in Lyra (The Lyre) and Altair in Aquila (The
Eagle)—rises after midnight in the east. Between them, in the south,
lies the ‘Spring Triangle’ of Arcturus in Bootes (The Herdsman),
Denebola in Leo (The Lion) and Spica in Virgo (The Maiden). Circumpolar
constellations—always above the horizon at the latitude of Edinburgh and
Lothian—include Draco (The Dragon), Perseus (The Hero), Cassiopeia (The
Seated Queen) and Camelopardalis (The Giraffe).
