THE SOUTHWORTH PLANETARIUM
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Altitude: 10 feet below sea level
Founded January 1970
Julian Date: 2459311.18
2020-2021: CVIII
THE DAILY ASTRONOMER
Tuesday, April 6, 2021
April 2021 Night Sky Calendar Part III
*TUESDAY, APRIL 20: MOON NEAR BEEHIVE STAR CLUSTER*
The image below shows the Beehive star cluster as it would appear in a
time-exposure photo, one in which the light is allowed to accumulate over
time so as to produce a meticulously detailed image:
[image: m44-praesepe-beehive-cluster.jpg]
In our sky, Praesepe, or the "Beehive Star Cluster," appears as a faint
smudge of light at the center of the constellation Cancer the Crab. The
moon will often appear to draw close to the Beehive star cluster because
Cancer, being a zodiac constellation, is aligned along the ecliptic, the
band through which the moon moves. Like the Pleiades, Praesepe is a
galactic star cluster, though a bit farther away at a distance of 577 light
years.
See the first quarter moon (50% illuminated) close to Praesepe tonight.
*THURSDAY, APRIL 22: LYRID METEOR SHOWER PEAKS (GOLD EVENT!!!)*
Tonight watch as approximately 20 - 45 meteors an hour appear to emanate
from a region surrounding Lyra the Harp, hence the name "Lyrids." As
the moon will be in the waxing gibbous phase, viewing conditions will not
be ideal in the early evening. However, the best time to observe meteors
is after midnight, at which time our part of the planet will be turning
into the meteoroid stream.
The parent comet is C/1861 GI Thatcher. It is this comet that cast off the
dust particle clouds through which Earth is presently traveling. When
these particles, called meteoroids, pass through the planet's upper
atmosphere, they excite the surrounding atoms to higher energy states.
When these atoms return to their original low energy configurations, they
emit photons we see as meteors.
Even if one misses the peak event tonight, one can still see Lyrids during
the following week. The Lyrid shower begins on April 14 and ends on April
30th. Tonight, Earth moves through the densest part of the meteoroid
stream.
*THURSDAY, APRIL 22: MOON NEAR REGULUS*Tonight, the waxing gibbous moon
(73% illuminated) appears to move close to the bright star Regulus, the
alpha star in Leo the Lion. The gibbous moon will be located just north of
Regulus, which marks the southern "point" in the lion's sickle, or backward
question mark.
[image: skychart.png]
*FRIDAY, APRIL 23: HERCULES UP SOON AFTER SUNSET*
Hercules is known as the "kneeling one," because the constellation is
depicted as kneeling on Draco's head. Hercules ascends into the
eastern sky soon after sunset and will remain visible all night. The
most prominent aspect of the Hercules' constellation is the 'keystone,' a
quadrilateral of stars that represents the warrior's mid-section.
[image:
herculescentered-5b2b08c304d1cf00362a834b.jpg]
One of the best ways to find Hercules is to first find the Big Dipper.
Follow the handle's arc down to the star Arcuturs (remember the mnemonic,
"Arc to Arcturus"). Arcturus is the brightest star in Bootes the
Sheepherder. Corona Borealis, the "northern crown," is just to the east
of Bootes. As one can see in the above image, Corona Borealis is also
just to the southwest of Hercules' keystone.
[image: Bootes-Big-Dipper.jpg]
So, find the Big Dipper => follow the handle's arc to Arcturus => move east
to Corona Borealis and then to Hercules.
*MONDAY, APRIL 26: MOON NEAR SPICA*
The waxing gibbous moon (99% illuminated) passes close to Spica, the
brightest star in Virgo the maiden. If nothing else, these monthly lunar
appulses might help one to identify some of the sky's brightest stars.
[image: skychart (1).png]
*TUESDAY, APRIL 28: FULL MOON (SUPER MOON!)*
We recall that the Super Moon is defined as a moon that is full when it is
also at or near perigee, the point of least distance from Earth. Tonight,
the moon is full and at perigee, as well. In fact, the moon reaches
perigee about twelve hours after it reaches opposition (becomes a full
moon.) The Super Moon is 30% brighter than 14% larger than the Micro
moon, defined as the full moon that occurs when the moon is at or near
apogee, its point of greatest distance from Earth.
[image: supermicromoon_paduraru_960.jpg]
The above image shows both a Super Moon and a Micro Moon. The Super Moon
is 30% brighter and 14% larger than a Micro Moon.
*WEDNESDAY, APRIL 29: MOON NEAR ANTARES*
See the waning gibbous moon (91% illuminated) close to Antares, the
brightest star in Scorpius the Scorpion. See them both traveling
through the southern sky after midnight.
*PLANET WATCH*
*MERCURY *
*Host constellation (early month): Pisces*
*Host constellation (late month): Aries*
One will find Mercury in the early morning sky at the beginning of the
month. By mid-month, Mercury vanishes into the pre-dawn glow and will be
lost to sight for the rest of April. VERDICT: The earlier the better.
Mercury-seekers should venture out sometime during the first ten days of
April to find the first world in the early morning eastern sky.
*VENUS*
*Host constellation (early month): Pisces*
*Host constellation (late month): Aries*
Venus is exceedingly difficult to find for most of April. By month's end,
one might just glimpse our sister world low in the early evening western
sky. VERDICT: Don't bother searching for Venus until the end of April.
Even then, one will have to go out soon after sunset to find it. Good
news: Venus will become easier to find in May and throughout the rest of
spring and summer!
*MARS (PICK PLANET!)Host constellation (early month): Taurus*
*Host constellation (late month): Gemini*
Even though Venus will make an appearance late this month, Mars essentially
has the evening sky stage to itself. At magnitude 1.4, Mars is about as
bright as Regulus, the brightest star in Leo the Lion. At month's
beginning, Mars sets about forty minutes after midnight. At month's end,
Mars will set a few minutes after midnight. VERDICT: Still moderately
bright, Mars remains an easy evening sky sight throughout April. Seek it
out before midnight in the western sky.
*JUPITER *
*Host constellation (early month): Capricornus*
*Host constellation (late month): Aquarius*
Although Jupiter will be rising progressively earlier each day, it remains
a morning sky object all month. At the beginning of April, Jupiter rises
around 4:45 a.m. At month's end, Jupiter rises at 3:00 a.m. Jupiter
brightens throughout April: magnitude -1.9 on April 1st and -2.1 on April
30th. Throughout the month, Jupiter will outshine Sirius, the night sky's
brightest star. VERDICT: Jupiter is a perfect planet for early risers.
It will be easier to find later this month.
*SATURN*
*Host constellation: Capricornus*
At magnitude 0.8, Saturn is about twelve times dimmer than Jupiter, it
rises earlier and might be easier to find. On April 1st, Saturn rose
at 4:08 a.m. On April 30th, the sixth world will rise around 2:15 a.m.
VERDICT: Saturn is rising into greater prominence and so will be easy to
spot, especially later in the month.
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