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Mountain Skies: Dark Skies For The Geminid Meteor Shower

 

December 3, 2018



The Planets

While it was nice back in the summer to locate the planets all in a line in the evening sky, they may seem to move around randomly. Of course, there is nothing random about their movements; ancient astronomers and math-ematicians have been able to plot their orbits and predict their appearances for centuries. But, for the casual viewer, their locations and movements demand a bit of attention to the dynamics of the solar system.

Let’s start with the two planets in our evening sky. Mars has been visible after sunset since late in the summer. It is that bright orange object high up in the south as the sky darkens. If you’ve been following it the past few months, you’ve noticed it hasn’t moved much but has become much dimmer. That’s because its current motion is almost directly away from the earth due to its motion and ours.

The ringed planet Saturn is still very low in the southwest, so low in the evening twilight that the observer will need at least binoculars to spot it. Saturn is disappearing into the sunsets and will pass behind the sun in superior conjunction on Jan. 2 to emerge in the morning twilight in January.

In the predawn sky, we have the other visible planets. Venus came out from behind the sun in early November and, Wow! It is absolutely brilliant. (I’ve been tempted to get a shirt with “It’s Venus!” on it for the many times people have asked me what that bright object is in the east at sunrise.) Below Venus, the elusive Mercury has now begun what astronomers refer to as a favorable morning apparition. By Dec. 15 it will be a full 21° from the sun and will be rising more than 90 minutes before our central star. Finally, the giant Jupiter was in conjunction behind the sun on Nov. 26 and it too is now rising in the morning twilight. On Dec. 21, by coincidence, the winter solstice, Jupiter and Mercury will be less than 1° apart as the biggest planet in our solar system passes the smallest.

The Geminid Meteor Shower

In 2018 the Geminids are calculated to reach a peak of about 120 meteors per hour around 8 a.m. EST on Friday, Dec. 14. Geminids should be seen for a night or two around this peak. Successful observing of the Geminids can start as early as 10 p.m. and continue until dawn as the constellation of Gemini, the twins, rises higher in the sky. This year a waxing crescent moon will be in our early evening skies, so its light will not interfere with observations of fainter meteors during prime observing hours around midnight to dawn. One should observe from a clear, dark location like PARI. Join us for a Geminids Meteor Shower Experience on Dec. 14.

The Stars

In the evening skies we can see that autumn is quickly coming to a close; the signs are seen not only in the woods and felt in the air, but also apparent in the sky above. The central figure of the autumn skies, Pegasus, the winged horse, has moved to the west. Alpheratz, the star at the northeastern corner of the Great Square of Pegasus, actually marks the head of the chained princess Andromeda. Her body stretches off to the east. Shining dimly at her waist is the Great Galaxy in Andromeda, known to astronomers as Messier 31 (M31).

Rising in the east, lying on his side, is the central figure of the winter skies, the magnificent hunter, Orion. Outlined by seven bright stars, he is following the great bull, Taurus, up in the east and is, in turn, followed by his faithful hunting dogs, Sirius and Procyon. A line formed by the three stars in Orion’s belt points westward to the Dog Star, Sirius, the brightest star in the nighttime sky. Sirius claims this status because it is larger and hotter than our sun and lies relatively close by at 8.6 light years, a mere 50,570,000,000,000 miles away.

The Sun

While we can’t see it in the daytime sky, we know that the sun has now crossed into Ophiuchus, the doctor. In modern times the path of the sun through the zodiac includes this very interesting constellation. The sun is “In Ophiuchus” from Nov. 30 through Dec. 17. On Dec. 18 the sun moves in front of Sagittarius, the archer.

Celestial Calendar

Dec. 7, 2:20 a.m. EST - New moon.

Dec. 14, 8 a.m. EST – Geminid meteor shower peaks.

Dec. 15, 6:49 a.m. EST – First quarter moon.

(About the Learning Center at PARI: The Learning Center at PARI is a public not-for-profit 501 (c) (3) organization established in 1998. Located in the Pisgah National Forest, the Learning Center provides STEM educational programs at all levels, from K-12 through post-graduate research. For more information about the Learning Center at PARI and its programs, visit http://www.pari.edu.)

 
 

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