[pleasant music playing]
Preston: What's Up for December.
Your early evening highlights.
A chance to catch a comet
and the annual Geminid meteors.
On December 6th through the 10th,
look westward following sunset for the Moon,
visiting Venus, Saturn, and Jupiter in turn.
The Moon's crescent fills out as it appears higher
in the sky each evening, over the course of the week.
Enjoy the view of dazzling Venus as our "evening star"
while it lasts though.
Our cloud-covered neighbor planet will sink ever closer
to the horizon during the month disappearing
for most of us by New Years'.
It'll reappear in late January as a morning planet
preceding the sunrise,
and won't be back in evening skies
until December of next year.
[Whoosh]
Next in December,
there's a recently discovered comet
on its way into the inner solar system
that might be worth trying to observe.
It's known as Comet Leonard
and it'll be at its closest to Earth on December 12th,
just a couple of weeks before it reaches
its closest distance from the Sun.
Now comets are notoriously difficult to predict
in terms of brightness and visibility.
Comet Leonard is predicted to peak at a brightness
that will probably require binoculars to spot it.
There's a chance it could be bright enough
to see with the unaided eye,
but again, with comets you really never know.
In the first couple of weeks of December,
Comet Leonard can be found in the east before sunrise
passing between Arcturus and the handle of the Big Dipper.
It approaches the horizon right around the time
of its closest approach to worth,
meaning it'll likely be brighter,
but more challenging to observe.
It then switches over to being an evening object
after around December 14th
for just a little while after the sun sets,
as it begins its long haul outward from the sun again,
progressively fading in brightness.
[Whoosh]
Finally, the Geminid meteors
are a highlight of December skies each year.
This year's meteor shower peaks overnight
on December 13th and 14th.
Apart from the weather,
the phase of the Moon is usually the main factor
in whether a meteor shower
will have good viewing any given year.
This year, the Moon will be almost 80% full
at the peak of the Geminids, which isn't ideal.
However, that bright Moon will set somewhere around 2:00 AM,
wherever you're located,
leaving a couple of hours for meteor watching before dawn.
The meteors appear to radiate from the constellation Gemini,
which you'll find high in the west.
Now while most annual meteor showers are caused
by Earth passing through trails
of dust-sized particles of comet debris.
The Geminids are one of the few meteor showers
that are caused by debris from an asteroid
that crosses Earth's orbit.
In this case, one called Phaethon.
Recently NASA scientists shared findings
that suggest the difference between an asteroid and a comet
might be less clear than we realized.
With fizzing sodium on Phaethon
playing the same role as vaporizing ice on comets.
And whether you catch a glimpse of Comet Leonard
or meteors from asteroid Phaethon,
both are reminders of the deep connections
between Earth and the rest of the solar system
that we discover because we look outward and we explore.
Here are the phases of the Moon for December.
You can catch up on all of NASA's missions
to explore the solar system and beyond at nasa.gov.
I'm Preston Dyches from NASA's Jet Propulsion Laboratory.
And that's What's Up for this month.