January 2019

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into three sections; what you can see with the naked eye, with binoculars, and with a small telescope. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on January 5th. For January, your best viewing nights will be from January 1st to the 11th and the 24th to the end of the month. The Star chart below is set for Florence, SC on January 15th at 9 pm.

The following is primarily a repeat of my September 2015 lunar eclipse column

Lunar Eclipse:

There will be a total eclipse of the Moon on the night of January 20th and 21st. For an amateur astronomer this is a pleasant celestial event; the lineup is shown below.

For the non-astronomers the media tends to embellish celestial events. I predict that the media will have a field day with this eclipse. First of all this month’s eclipse occurs when the Moon is at perihelion; closest to the Earth. At its closest approach, the Moon is only 5% closer than the average Earth – Moon distance. Your eyes may or may not perceive that the Moon appears closer and therefore larger at perihelion. However, the media will not mention average Moon distance or percentages, but they will instead call it a “Super Moon”! Therefore this will be a “Super Eclipse”! This hype is deceptive, but at least it is based on orbital mathematics. Some news organizations go far beyond simple deception as shown in the image of a super Moon at perihelion in USA Today.

I predict that the second media hype will be directed at the subject of a “Blood Moon”. What is a Blood Moon? It’s the new media term for a total lunar eclipse. Most total lunar eclipses have a reddish brown color. One might logically think that if the Earth totally blocks the light of the Sun from reaching the Moon, then the Moon should look black during a total lunar eclipse. If the Earth had no atmosphere, then this would be true. However, the Earth’s atmosphere acts like a lens and bends the Sun’s light around the Earth. We know from red sunsets that only the long wave red and orange can penetrate farthest through our atmosphere, therefore the small amount of light that reaches the Moon during a total lunar eclipse would have a reddish color; no blood, just physics, see below.

One recent headline from a famous cable news network was:

“Stargazers will witness a trifecta of lunar events in the New Year — a total lunar eclipse, a super blood Moon and a “Wolf Moon,” a nickname for a full Moon that appears in the middle of winter.”

So now we added a wolf. So you can go out and see a Super Blood Wolf Moon, or just go out and enjoy a fun lunar eclipse and leave all the hype to the non-scientific branch of the news media.

It’s a ball!!!

I will make a final prediction for this month’s column. I predict that what I am about to tell you next about this month’s lunar eclipse will not be mentioned by any other non-science or science columnist!

First some background: If the Moon is a sphere, why don’t we see it as a three dimensional ball in the sky, instead of a flat disk? Most people say because it is too far away to see the curvature, but this is not so.

The first Moon landing finally cleared up this question. When the astronauts walked on the Moon, they noticed that the surface is covered with a fine powder. This fine dust tends to diffuse/scatter the bright Sun’s reflected light, called Lambertian reflection.   A surface which gives equal reflectance at all observing angles is Lambertian reflectance, and this is what prevents us from seeing the Moon as a ball. Now, during a total lunar eclipse, the Moon is only dimly lit by a small amount of reddish sunlight refracting/bending around the Earth’s atmosphere. Under this low light, the bright diffuse of reflected light is gone and a spherical Moon can sometimes become apparent. Observing a three dimensional Moon during a lunar eclipse is best achieved when the Moon is high in the sky from 10 pm onward, and this month’s eclipse will be in totality from January 20th at 11:41 pm until January 21st 12:43 pm. There are many other variables in play affecting seeing a spherical Moon, but the timing of this eclipse sets up a great chance of seeing this effect.

So check it out this month, and for the first time in your life you may see the Moon as a sphere.

The December Geminids:

For all of us in South Carolina the Geminids meteor shower was a washout due to heavy cloud cover. The next Geminids shower without interference from a bright Moon will be December 2020.

 

Naked Eye Sights: Lunar eclipse. The stars of winter. Ask some of your friends this month if they ever saw or heard of the constellation Orion. For those who say no, take them outside this month, and introduce them to the wonderful Orion constellation.  If you bring out binoculars, show them the “fuzzy” Orion Nebula. While you are outside, also point out the brightest star in the night sky, Sirius, plus the pretty binocular view of the Pleiades.

Binocular Sights (7 to 10 power): Lunar eclipse. The Orion Nebula and the Pleiades.

Telescope Sights (60-100mm: Since you went outside to see the eclipse, use the hour of darkness to check out your favorite targets. The planet Mars is still visible in the western sky.

Dobsonian telescope (6 -8 inch): The planet Mars is still visible. Try checking out the young stars in the center of the Orion Nebula.

Comments are closed.