Blue Moons, Blood Moons, and Super Moons: Separating Fact from Fiction

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[Total lunar eclipse. Courtesy NASA]

Prepare to be inundated with lunacy this week, thanks to three interesting configurations of our nearest celestial neighbor. Wednesday the 31st is the second full moon of January, making it the so-called “blue moon” (as in “once in  a blue moon”). But just how rare is a blue moon? Not very, if you consider that the time between two consecutive full moons is about 29.5 days, and all months except February have more than 29.5 days in them. For example, March 2018 also has two full moons.

The “blood moon” descriptor refers to a total lunar eclipse. When the sun, earth, and moon line up in that order in a straight line, the earth casts a shadow on the otherwise full moon. Because the red portion of sunlight refracts or bends through our atmosphere, the full moon doesn’t turn black but a coppery or bloody red. While it can be a startling sight to those who aren’t expecting it (I remember being scared to death as a child when I saw a lunar eclipse during a late night potty break), there is nothing bloody or gruesome about the event. On average one or two total lunar eclipses occur each calendar year. The January 31 total lunar eclipse will not be visible from here in Connecticut, as the moon will be setting as the eclipse begins. Our next chance to see a “blood moon” will be January 21, 2019.

Well, what about the so-called “super moon?” This refers to the full moon looking larger than average. Because the moon’s orbit around the earth is not a perfect circle, when the moon is at its closest point to earth (called the perigee) it looks 14% larger than when it is at its farthest point (called apogee). When this happens at the time of full moon, you might notice that the moon looks a little bit brighter than average. There is no scientific definition of a super moon (because it’s not really something that scientists care about, to be honest), but one running definition on the internet is that it is when the full moon occurs within a few days of perigee. So how rare is this? Considering that the first full moon of January 2018 (which occurred on New Year’s Day) was also a “super moon,” you have your answer.

Putting all three of predictable, cyclical configurations together into one event, however, is just a tad more rare. The last “blue-blood-super moon” was probably in 1866 (again, depending on your definition of “super moon”). So if you want to take this opportunity to go outside and gawk at dear old Luna, please be my guest. Just don’t howl, because you might be mistaken for a super blue werewolf!

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Perihelion and Palantiri: A Reflection on January 3, 2018

[Earth’s orbit (Courtesy NASA); J.R.R.Tolkien (Courtesy  The Tolkien Society]

Given the weight of the stories burying your social media on January 3 this year (including “bombogenesis”), you might have missed two less sensational annual events. At 12:35 AM EST, the Earth passed closest to the sun in its orbit, a point called perihelion (“around sun”). The actual time of perihelion varies a little bit each year, occurring some time between January 2-4. As you can see from the above diagram, we are not that much closer to the sun in January than we are at the farthest point (around July 4-5), called aphelion (“from sun”). A common misconception is that it is the shape of the earth’s orbit that causes seasons – being closer causes summer and being farther away causes winter. This misconception is fed by diagrams in science textbooks that greatly exaggerate the shape of our orbit, drawing it as an elongated ellipse rather than the rather more circular shape it actually has. The seasons are instead caused by the 23.5 degree tilt of earth’s axis.

The second annual event that was widely publicized on my social media was the 126th birthday of author J.R.R. Tolkien (January 3, 1892September 2, 1973), best known for The Hobbit and The Lord of the Rings. Among Tolkien fans it is a tradition to raise a toast to Tolkien at 9 PM local time on January 3 and proclaim “The Professor!” You might be wondering why I have included Tolkien in an astronomy blog. What many readers of Tolkien’s works miss is that he has a plethora of (often fairly accurate) references to astronomy in his fantasy! From the moon runes of The Hobbit to the various references to the sun, moon, stars, eclipses and more in The Lord of the Rings and his grand mythology The Silmarillion, Tolkien’s use of astronomy in his fantasy reveals his impressive knowledge of the night sky. Tolkien certainly wasn’t the first or last fantasy writer to integrate the night sky into his fantasy world, but unlike his friend C.S. Lewis, Tolkien felt it important to get the astronomy “right.” In fact, when he considered revising his unfinished mythology in the last decades of his life, he toyed with completely revising it to avoid trying to describe a mythological creation of the sun and earth, and used the then-current hypotheses concerning the formation of the moon as his guide.

So as you can see, January 3, 2018 gave this astronomer two reasons to celebrate. January 4, on the other hand, is just giving me an astronomical amount of snow to shovel….

CCSU Astronomy Students Shine in Free Public Observing Sessions

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[Former AST 278 student Vanessa Swenton running the 10 inch Newtonian during a public observing session]

Each Fall semester, the students in AST 278 Observational Astronomy get an opportunity to shine. The capstone project of the course is for the students to plan, publicize, and carry out a series of four consecutive nights of free public observing sessions.

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[Poster for the 2017 observing sessions. Designed by current AST 278 student Hayley Comstock]

This year’s class creatively adopted a Van Gogh theme, using the slogan “Gogh and experience a Starry Night at CCSU.” On December 3-6 from 7-8:30 PM, if the skies are clear, the 15 students will run four different telescopes and two sets of mounted binoculars, each instrument observing a different double star, star cluster, or galaxy. The students have spent a great deal of time preparing for this event, practicing how to operate the instrument they are assigned to and finding their object, as well as researching information about the instrument and object (including mythology and “fun facts”). But the success of this event really depends on you, the general public, to attend and allow these students to prove what they can do. I hope you will join us – I know you will be as proud of our CCSU astronomy students as I am.

For more information, including directions, visit the Copernican Observatory and Planetarium website.

Giving Thanks on Giving Tuesday

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On this Giving Tuesday I wanted to give thanks for the honor and opportunity of serving as one of CCSU’s celestial tour guides since 1989. Last night my Observational Astronomy class practiced for their public observing sessions (this coming Sunday through Wednesday, December 3-6 – more on this tomorrow!) and I was impressed with how far they’ve come since the first night in the observatory in late August. Some of them had never looked through a telescope before seeing Saturn and Jupiter that first night. Now they are operating the instruments without my help, slewing across the night sky by hand and finding galaxies, star clusters, and double stars.

It definitely took hard work on the part of the students to get to this point, and the Copernican Planetarium here at CCSU played an important role. On cloudy nights we would use the planetarium to hone the students’ skill in pointing out the constellations and bright stars and navigating their way across the sky from horizon to horizon.

As you might imagine, planetariums and observatories need upkeep, and it isn’t cheap. While the university graciously supports our endeavors to keep the night sky free for all to enjoy by paying for our base budget, yearly service contract, and single fulltime staff member, we sometimes have to rely on the funds we raise ourselves to supplement this (for example, when we brought in a contractor to service the observatory dome). I am proud to say that I donate to the planetarium fund every year, but I don’t want to be selfish – I want to invite everyone to be a “star” and have the joy and satisfaction of knowing that they helped support our good work in bringing the universe down to earth for the citizens of Connecticut and beyond.

So on this Giving Tuesday, I am giving thanks by renewing my support for our projects, and invite you to do so as well. The sky belongs to all of us; let’s hold hands and support it together!

Gogh and Experience a Starry Night at CCSU

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You’ve seen the famous painting, now experience the real thing by viewing galaxies, star clusters, double stars and more through a variety of telescopes and mounted binoculars at Central Connecticut State University. On December 3-6 from 7:00 – 8:30 PM, if the skies are clear, join us for free public observing sessions hosted by CCSU astronomy students. Bring along your own binoculars to learn how to use them to paint a picture of the universe from your own backyard. We promise it will make an impression on you! For more information, visit www.ccsu.edu/astronomy or call 860-832-2938.

 

When you wish upon a… piece of Halley’s Comet?

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Have you ever heard the superstition that you should wish upon a falling star? If you do that this week, you might just be wishing upon a piece of Halley’s Comet burning up in our atmosphere! Falling or shooting stars have nothing to do with stars. Instead, what scientists call meteors are flashes of light caused when a tiny piece of a comet enters our atmosphere and burns up. Imagine your car driving into a swarm of insects and watching them go splat on your windshield. That’s not a bad analogy for the earth running into a swarm of meteoroids, debris liberated by a comet as it orbits the sun. When earth passes through the orbit of a particular comet (which, for any particular comet, will occur at the same time each year), many of these meteoroids burn up, creating a meteor shower. A meteor shower is named not after the comet whose particles create it, but rather where in the sky the meteors seem to radiate from, or the radiant. The brightest constellation in the region usually lends its name.

We are currently in the midst of the Orionid meteor shower, whose radiant lies between Orion’s bright shoulder star Betelgeuse and the bottom stars of Gemini (see above). Depending on how the meteoroid field is configured (for example, the size and number of particles, and the width of the meteoroid field), a meteor shower can last for a few days up to a few weeks, but there is usually a narrow window where we hit the densest part of the stream and hence see the largest number of meteors per hour. This year the Orionids are expected to peak in the predawn hours of Saturday, October 21.

The Orionids are certainly not the best meteor shower of the year (at peak you might only see 20 per hour, and each meteor is not particularly bright), but it has a unique romantic charm due to the identity of its parent comet, Comet P/Halley, or as most people know it, Halley’s Comet. While the comet itself won’t be in our neighborhood again until 2061, each year we actually get two meteor showers from the material it left behind on previous journeys around the sun – the Orionids in mid-October and the Eta Aquarids in early May.

If you find yourself up before dawn this week, why not take a peek out your window in the direction of Orion, and see if you can make a wish on an Orionid – mine will certainly be to be alive when Halley’s Comet returns in 2061 so I can become a member of the Halley’s Comet two-timer club!