THE SOUTHWORTH PLANETARIUM
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Founded January 1970
Julian Date: 2458821.16
2019-2020: LXIII
"Heavens on the half shell."
THE DAILY ASTRONOMER
Tuesday, December 3, 2019
December 2019 Night Sky Calendar Part II
___________________________
Dedicated to my future stepchildren
Sebastian, Serena, Kai and Soleil.
Without their help, I would have posted this
article on time.
____________________________
*SATURDAY, DECEMBER 14: GEMINID METEOR SHOWER PEAKS (SILVER EVENT!!)*
Meteors are mesospheric events, meaning that they generally occur high in
the Mesosphere, between 75 - 100 kilometers above Earth's surface. This
altitude is just at or below the Karman Line (100 km) that marks the
official boundary of outer space. Meteors are the lights we see when
meteoroids infiltrate our upper atmosphere. The meteoroid heats up as it
descends and excites the nearby atmospheric atoms, meaning that the
electrons within them are elevated to higher energy states. When the
electrons revert to their previous states, they emit the photons we
perceive as "meteors."
Meteor showers are named for the constellation from which the meteors
appear to emanate. The Geminid meteors appear to come out of the
constellation Gemini. One can best see these meteors after midnight,
when our part of the planet is turning into the densest part of the meteor
stream.
Ordinarily, one would be able to see about 30 - 40 meteors an hour from
this shower. Unfortunately, this year we can expect significant lunar
light interference as the moon will be in the waning gibbous phase (92%
lluminated) and will rise by 6:36 p.m. All the same, one should venture
outside tonight to catch a glimpse of a Geminid meteor. They tend to be
bright and travel at medium speed.
*WEDNESDAY, DECEMBER 18: MOON AT PERIGEE*
Yesterday we spoke about the moon's elliptical orbit. As the moon travels
along its path, its distance from Earth varies constantly. During each
circuit around Earth, the moon reaches its closest point (perigee) and
about two weeks later arrives at its most distant point (apogee) . Today
the moon is at perigee. At the precise moment of perigee, the moon will be
370,265 kilometers from Earth.
*THURSDAY, DECEMBER 19: LAST QUARTER MOON*
*SATURDAY, DECEMBER 21: WINTER SOLSTICE (11:19 p.m.) [Gold event!!!]*
Astronomical winter officially begins tonight! To explain why winter is
starting now and not on December 1st as the meteorologists assert, we need
to discuss Earth's annual motion. Earth revolves around the Sun once a
year. As it is tilted on its axis 23.5 from vertical, the northern
hemisphere is alternately pointed toward and then away from the Sun during
each revolution. Winter begins when Earth's north pole is directed away
from the Sun as much as possible. Summer begins when the north pole is
aligned toward the Sun by the greatest amount.
Although winter begins tonight, we can expect the duration of daylight to
slowly increase from now until the summer solstice in June 2020. Of
course, as we are now facing a few months of biting cold, lacerating winds
and blinding snow, the notion of the increased day length might prove a
hollow comfort.
*MONDAY, DECEMBER 23: MOON NEAR MARS*The waning crescent moon (7%
illuminated) appears close to the fourth planet in the eastern pre-dawn
sky. While Mars is now as bright as Castor, Gemini's second brightest
star, it remains quite low along the horizon. Those observers seeking
Mars will find it easier to find the planet tonight as the moon hovers
around it.
*THURSDAY, DECEMBER 26: ANNULAR SOLAR ECLIPSE THAT WE WON'T SEE*
Consider this a purely academic event. The moon will move directly in
front of the Sun. However, as the moon will be at a more distant point in
its orbit, it will appear smaller than the Sun and so won't block it
entirely. During totality. a ring of light will remain visible around the
Sun, hence the term "annular solar eclipse," from the latin "annulus" for
"ring." This eclipse will be visible along a small path slicing through
Saudi Arabia, Southern India, Sumatra, Singapore, Borneo and Guam.
On the bright side, only 1565 days until the solar eclipse on April 8,
2024!
*THURSDAY, DECEMBER 26: NEW MOON*
Beginning of lunation cycle 1200
*FRIDAY, DECEMBER 27: MOON NEAR SATURN*
The thin waxing crescent moon (3% illuminated) veers "close" to Saturn in
the early evening western sky. Both the moon and Saturn will set by 5:20
p.m.
*SUNDAY, DECEMBER 29: MOON NEAR VENUS*
A gorgeous sight! The brightest planet next to the crescent moon (13%
illuminated) in the western evening sky. Both Venus and the moon will
set by 7 p.m. so be sure to venture out early to see them both!
*PLANET WATCH*
*MERCURY *spends most of the month in the eastern pre-dawn sky. By the
last week of December, Mercury will vanish into the dawn light, only to
rise in the western evening sky in the new year. VERDICT: Best to see
Mercury during the first two weeks of December.
*VENUS:* A low, western sky planet. Still brighter than any sky object,
apart from the Sun and moon, Venus will still be easy to find provided one
ventures outside by 6:30 p.m. to find it. VERDICT: One should have no
problem finding Venus in the early evening western sky.
*MARS:* Mars is still low in the eastern pre dawn sky, but is slowly
growing brighter. In October 2020, Mars will be at opposition, meaning
that Earth will pass between Mars and the Sun. VERDICT: If you're out
in the early morning, seek out Mars. Of course, Mars will become
easier to observe throughout the winter and spring as it moves into a more
prominent position.
*JUPITER *vanishes into the dusk by mid month. However, this behemoth of a
planet isn't really visible at all this month. VERDICT: If you must see
Jupiter, see it during the first week of December. By the second week,
Jupiter is too low to be seen. Jupiter will return to the early morning
sky in January,
*SATURN: * follows Jupiter into the light of dusk. However, Saturn will at
least remain visible until late this month. VERDICT: Even though Jupiter
isn't easy to spot this month, Saturn remains in view at least for most of
December. Seek it out if you're outside in the evening.
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