December’s Lunar Eclipse and Mystery Meteor Shower

Robert Bigelow
On the morning of December 10, the Moon will move through Earth’s shadow producing a total lunar eclipse. For observers in Utah, the Moon will set about the time of greatest eclipse. Sharp-eyed observers should detect the Moon entering into Earth’s umbral shadow at 5:46 a.m. Look for the Moon in the west, about 20 degrees above the horizon. Totality begins at 7:06 a.m. At this time the Moon will appear about 5 degrees above the horizon and could be hidden behind mountains from some observing locations. Moonset for a flat horizon is 7:44 a.m. For the longest view of the eclipse, find an observing location with a clear horizon in the west-northwest.
Meteor showers occur when Earth passes through a stream of debris given off by a comet. Particles that make up this debris stream typically range in size from pebbles to sand grains. As they enter Earth’s upper atmosphere at high speeds, they vaporize 50 miles above our heads, producing the slivers of light streaking across the sky that we call a meteor or “shooting star”.
Earth passes through a particular particle stream every year about December 14 producing what is known as the Geminid meteor shower. This shower suddenly appeared in 1862, surprising onlookers who observed dozens of meteors streaking away from the constellation Gemini.
Astronomers began searching for a comet as a source of the particles. Their search was unsuccessful until 1983, when NASA’s Infra-Red Astronomy Satellite (IRAS) spotted an object, several miles across, moving in about the same orbit as the Geminid debris stream. The object was named 3200 Phaethon. Oddly, Phaetheon seems more like an asteroid. It is rocky, not icy, and has no obvious tail. If Phaethon is an asteroid, how did it produce a stream of particles? Perhaps a collision with another space rock created a cloud of debris that follows Phaethon in its orbit around the Sun. Another possibility is that Phaetheon could be a defunct comet that has had all its ice vaporized. The mystery continues.
On a dark, moonless night, the Geminid meteor shower can produce as many as 120 meteors per hour for observers far away from city lights. However, this year the meteor shower occurs four days after the full moon. So, moonlight from a waning gibbous moon should greatly reduce the number of visible meteors. The shower peaks on December 14 at 11 a.m. MST, so observers in Utah should look on the nights of the 13th and 14th.

On the morning of December 10, the Moon will move through Earth’s shadow producing a total lunar eclipse. For observers in Utah, the Moon will set about the time of greatest eclipse. Sharp-eyed observers should detect the Moon entering into Earth’s umbral shadow at 5:46 a.m. Look for the Moon in the west, about 20 degrees above the horizon. Totality begins at 7:06 a.m. At this time the Moon will appear about 5 degrees above the horizon and could be hidden behind mountains from some observing locations. Moonset for a flat horizon is 7:44 a.m. For the longest view of the eclipse, find an observing location with a clear horizon in the west-northwest.

Geometry of a lunar eclipse

Geometry of a lunar eclipse

Meteor showers occur when Earth passes through a stream of debris given off by a comet. Particles that make up this debris stream typically range in size from pebbles to sand grains. As they enter Earth’s upper atmosphere at high speeds, they vaporize 50 miles above our heads, producing the slivers of light streaking across the sky that we call a meteor or “shooting star”.

Earth passes through a particular particle stream every year about December 14 producing what is known as the Geminid meteor shower. This shower suddenly appeared in 1862, surprising onlookers who observed dozens of meteors streaking away from the constellation Gemini.
Geminid meteor shower courtesy of National Geographic

Geminid meteor shower courtesy of National Geographic

Astronomers began searching for a comet as a source of the particles. Their search was unsuccessful until 1983, when NASA’s Infra-Red Astronomy Satellite (IRAS) spotted an object, several miles across, moving in about the same orbit as the Geminid debris stream. The object was named 3200 Phaethon. Oddly, Phaetheon seems more like an asteroid. It is rocky, not icy, and has no obvious tail. If Phaethon is an asteroid, how did it produce a stream of particles? Several possible explanations have been proposed. None are completely satisfactory. The mystery continues.

On a dark, moonless night, the Geminid meteor shower can produce as many as 120 meteors per hour for observers far away from city lights. However, this year the meteor shower occurs four days after the full moon. So, moonlight from a waning gibbous moon should greatly reduce the number of visible meteors. The shower peaks on December 14 at 11 a.m. MST, so observers in Utah should look on the nights of the 13th and 14th.

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3 thoughts on “December’s Lunar Eclipse and Mystery Meteor Shower

  1. Are you going to have an event where we can gather to watch the lunar eclipse in Utah?
    Where are you meeting to see this?
    In AZ, the astronomy club met several times to view astrological events.
    Is there a similar thing here in SLC?
    Tnx
    exo

  2. Hi Exo,

    Clark Planetarium isn’t hosting a viewing party for this eclipse. Both the time of day and horizon will make this particular eclipse tough for some to see.

    If anyone out there does happen to catch a glimpse of the eclipse, we would love to hear about it.

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