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Stargazing

By David Huestis, Historian, Skyscrapers, Inc.

A Meteor Shower, a Blue Moon, and No More Iridium Flares, Oh My!

It’s challenging to explain to someone that you spent a below-freezing December night sitting on your back porch bundled up in a sleeping bag on a lounge chair just to watch a few meteors blaze across the sky. Why? Because sometimes even I question why I choose to do so. A few months back the Geminid meteor shower did not perform well around here, at least not when I decided to observe it. After about an hour and a half I counted less than a dozen meteors, and not all of them were Geminids. Only a couple of them were bright enough to elicit a wow, though not loud enough to wake my neighbors!

That’s the way it is with meteor showers. Sometimes you’re in the right place at the right time to see the meteors to best advantage. Other times you are not. It can be frustrating when the latter occurs, especially when the weather conspires against you. Still, after all my decades of stargazing I never tire of watching for meteors to fall from the sky.

The early days of May present us with warmer weather prospects to enjoy a somewhat “meteor-ocre” display of shooting stars. During the pre-dawn hours of May 5 and 6, the Earth will be sweeping through a stream of particles shed by Halley’s Comet long ago. (Either morning will be a fine time to observe since the Eta Aquarids do not have a sharp peak. The meteors comprising this meteor shower enter the Earth’s upper atmosphere head-on at 41 miles per second. While the Moon will not interfere with observing this shooting star display this year (New Moon is on the 4th), one can expect to see no more than 10-15 swift and yellow shooting stars per hour from Southern New England. Why? The Eta Aquarids, are best observed from the southern hemisphere.

The meteors appear to radiate from the constellation of Aquarius, not a very prominent star pattern. Around 4:00 a.m. Aquarius will be located about 12 degrees above the east-southeast horizon. The shower’s radiant point is in the Water Urn asterism (looks like a Y-shaped group of stars). While the meteors emanate from this region of the sky, scan around the entire sky to maximize your chances of observing one.

What’s in a name? Many of the full moon names have been borrowed from Native American cultures. Whereas others have come from the early American settlers who brought them over from Europe. There does not seem to be any rhyme or reason for favoring the use of one over the other. Native Americans called May’s full moon the Full Flower Moon because spring flowers were heralding a new season, Other names less frequently used are Full Corn Planting Moon and the Milk Moon.

I’m sure you’re familiar with the term Full Blue Moon. In 1946 it was mistakenly ascribed to having two full moon’s in a month. Two full moons in a month can occur when one happens at the very beginning of a month and at the very end because there is approximately 29.5 days between successive full moons. This modern definition apparently resurfaced in the mid-1980s.

See this Sky and Telescope article for a detailed explanation: https://www.skyandtelescope.com/observing/celestial-objects-to-watch/what-is-a-blue-moon/ The original definition of a Blue Moon was used to describe the third of four full moons during an astronomical season. That is, from winter solstice to vernal equinox, from vernal equinox to summer solstice, etc. Usually only three occur, but occasionally there can be four. Having made that distinction, the full moon of May 18 qualifies as a Blue Moon. Here’s the reasoning.

Spring began on March 20 at 5:58 p. m., EDT. The first full moon of the spring season was on the same day at 9:43pm EDT. The second one was on April 19. The third is on May 19. And the fourth will be on June 17. The summer solstice begins on June 21.

So using the original definition for a Blue Moon that means the full moon of May 18 will be a Blue Moon. Just remember, the Moon will not be blue in appearance. That only happens when particulates of a specific size are suspended in the Earth’s atmosphere after volcanic eruptions or large fires. The particles scatter the red light so a predominant blue end of the spectrum prevails.

Finally, the end of an era has come for getting flashed by a “constellation” of satellites orbiting the Earth. Iridium satellites were low-earth orbit communications satellites that were designed to be the “cell phone” technology of its day (1997). The service was too expensive for the general public and the technology quickly changed, so that business venture went bankrupt. The satellites were purchased by private investors for cents on the dollar and were spared a fiery re-entry into Earth’s atmosphere.

A ground observer could observe a flash of light off the satellite’s highly reflective antennae. These Iridium flares were very predictable. Sometime the flares would be many times brighter than Venus. Others not so much. The brightness of the flare depended upon an observer’s location, location, location!

When very bright flares were predicted I would even interrupt my astronomy labs at Bryant and usher my students outside to witness these events. Students were amazed how bright the flares would be. And during public nights at the local observatories Iridium flares were always crowd pleasers.

Unfortunately the original Iridium satellites are being replaced by Iridium NEXT, a next generation of communication satellites. An old satellite is initially positioned into a parking orbit. After the NEXT version is moved into place and tested, the old spacecraft will be de-orbited. Many have already met their fiery demise. Unfortunately for us observers the design of the Iridium NEXT satellite is not expected to produce any flares.

The Heavens Above (http://www.heavens-above.com/) website where predictions for the flares could be found continues to be a valuable resource for a variety of astronomical information. One can still find predictions for many other satellites, as well as observing windows for viewing passes of the ISS (International Space Station). That orbiting laboratory is an inspiring sight, especially when you realize a crew of six (April, 2019) orbit the Earth every 90 minutes or so at an altitude on average of 248 miles. Even though you won’t get flashed, the experience is still impressive.