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The December φ-Cassiopeid meteor shower will be active from 1 December to 8 December, producing its peak rate
of
meteors around 6 December.
Over this period, there will be a chance of seeing December φ-Cassiopeid meteors whenever the shower’s radiant point – in the constellation
Andromeda
– is above the horizon, with the number of visible meteors increasing the higher the radiant point is in the sky.
Seen from Los Angeles
,
the shower will be active each day from dusk until around
06:08
when its radiant point sets below your western horizon.
The shower is likely produce its best displays in the hours around 20:00 PST, when its radiant point is highest in the sky.
At this time, the Earth’s rotation turns Los Angeles to face optimally towards the direction of the incoming meteors, maximising the number that rain vertically downwards, producing short trails close to the radiant point. At other times, there will be fewer meteors burning up over Los Angeles, and they will tend to enter the atmosphere at an oblique angle, producing long-lived meteors that may traverse a wide area of the sky before completely burning up.
The shower is expected to reach peak activity at around 10:00 PST on 6 December 2023.
Observing prospects
The shower will peak close to new moon, and so moonlight will present minimal interference.
The origin of the shower
Meteor showers arise when the Earth passes through streams of debris left
behind in the wake of comets and asteroids. Over time, the pieces of grit-like
debris in these streams distribute themselves along the length of the parent
object’s orbit around the solar system.
Shooting stars are seen whenever one of these pieces of debris collides with
the Earth’s atmosphere, typically burning up at an altitude of around 70 to 100
km.
On certain days of the year the Earth’s orbit passes through particularly dense
streams, associated with comets or asteroids which have vented particularly
large amounts of solid material to space, and this gives rise to an annual
meteor shower. Such showers recur on an annual basis, whenever the Earth passes
the particular point in its orbit where it crosses the particular stream of
material.
All of the meteors associated with any particular shower appear to radiate from a common point on the sky
(not drawn to scale).
The meteors that are associated with any particular meteor shower can be
distinguished from others because their paths appear to radiate outwards from a
common point on the sky, which points back in the direction from which their
orbital motion brought them.
This is because the grit particles in any particular stream are travelling in
almost exactly the same direction when they cross the Earth’s orbit, owing to
having very similar orbits to the parent object they came from. They strike the
Earth from almost exactly the same direction, and at the same speed.
To see the most meteors, the best place to look is not directly at the radiant
itself, but at any dark patch of sky which is around 30–40° away from
it. It is at around this distance from the radiant that the most meteors will
be seen.
By determining the position of this radiant point on the sky, it is possible to
work out the orbit of the stream giving rise to any particular meteor shower.
It is sometimes even be possible to identify the particular body responsible
for creating the debris stream, if there is a known comet or asteroid with a
very similar orbit.
The radiant of the December φ-Cassiopeid meteor shower is at around right ascension
01h30m, declination 50°N, as shown by the green circle on the planetarium above.
The sky on 6 Dec 2023
Source
The position of the radiant of this shower, and its predicted hourly rate, were
taken from International Meteor Organisation’s
List of Meteor Showers.
Image credit
© Jacek Halicki 2016. Perseid meteor seen in 2016 from Poland.
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