Sudekum Planetarium

Venus on the Move, Saturn Sitting Still

Brilliant Venus continues to dominate the evening sky this month. The brightest object in the night sky other than the Moon, it appears high in the west just after sunset.

Venus orbits the Sun faster than the Earth. It’s quick motion combined with its closeness to Earth makes Venus appear to move against the backdrop of stars quickly from night to night. At the beginning of May, you’ll find Venus shining just below Auriga the Charioteer. By the middle of the month, it will be just west of Gemini the twins, and as June begins, you’ll find it on the east side of Gemini.

Meanwhile, beautiful Saturn orbits slowly and is very far away from us. It hardly seems to move much at all. It starts the month right between Cancer the Crab and Leo the Lion. At the end of the month, it’s... still in the same place. In fact, Saturn will still be there July 1, when Venus catches up to it. On that day, Venus and Saturn will be less than one degree apart. In many telescopes, you’ll be able to see them both at the same time!

Blue Moon in May

For some time, it has been said that a ‘blue moon’ occurs when there are two full moons in one calendar month. That is a popular bit of folklore, but it has only come into vogue in the last twenty years or so.

Actually, it is possible for any phase to occur twice in one month if the first phase (NM, FQ, FM, or LQ) happens during the first two days of the month. Because the cycle of the Moon’s phases repeats over the course of 29 days, that same phase will come back around by the 30th or 31st of the month. The special significance of two full moons in one month might be because a full moon is so distinctive and noticeable.

As a matter of fact, two full moons in one calendar month happens on average every 2.7 years, but it can be longer or shorter depending on how the calendar falls.

Another complication is that there is a very specific moment in time when astronomers say that full moon occurs. As a standard, astronomical events are given in UT (Universal Time), what used to be GMT (Greenwich Mean Time), or the time at the Prime Meridian in Greenwich England. Because of time zones and England being several hours east of us, it can be June 1st UT while still being May 31st here in the United States.

In my handy book of astronomical tables, two full moons are listed for June 2007. The first one occurs at 1:04 UT on June 1. Nashville is currently observing Central Daylight Time, CDT, which is five hours behind UT. Translated, that means that the time of full moon is really 8:04 PM CDT on the evening of May 31. Because of this discrepancy, some published calendars will show the blue moon in June.

For those who are curious, the next ‘blue moon’ after this will be in December, 2009. That leads to another widely recognized meaning for ‘blue moon’ - something that happens infrequently, just like having two full moons in one calendar month.

There have been times when the Moon has actually appeared blue. After the eruption of the Indonesian volcano Krakatoa in 1883, there was so much volcanic dust in the upper atmosphere, sunsets were green and the Moon looked blue - for almost two years. Even to this day in the 21st century, the phrase, ‘once in a blue moon” still refers to an event that rarely takes place.

Before that, the term meant ‘never’, as in “I’ll marry you, m’lady, when the Moon is blue!” An euivalent today would be ‘when pigs fly’.

The oldest references go back almost five hundred years! “Yf they say the mone is blewe, we must believe that it is true.” This is interpreted to mean that the idea of a blue moon was completely absurd. Taken one step farther is “They woulde make men beleue ... that ye Moone is made of grene cheese.” This was recognized as a silly idea even in the early 1500s.

To celebrate the concept of a blue moon, Warner Park Nature Center will be hosting a Blue Moon Party on May 31, from 7:30 to 9:30 PM. Call the Nature Center at 352-6299 for more information.

Construction Update

Day 116: When we last saw the stars of the old Sudekum Planetarium on January 7, we knew that a year and a half would be a long time to wait. We’re just starting month five and realizing what an understatement that was. We need stars! Of course the real sky offers some relief, but the local light pollution only whets our appetites for a crisp, cloud-free, dark starry scene.

If you’ve visited (or even just driven past) Adventure Science Center recently, you probably haven’t noticed a lot of change. A massive circular wall is up, highlighting the exterior wall surrounding the planetarium. Inside the wall, away from view, conduits and pipes are being laid down in the foundation. Important, but maybe not the most exciting thing to watch. Soon, steel to be delivered to the construction site, and that’s when the real excitement should begin. Don’t forget to check back here for frequent updates!