October meteor showers

    If recent events during the last few months are any indicator, Chicken Little may have been right. The sky is falling. The sky is falling. Back on July 24 at approximately 2:44 a.m. EDT, a soccer ball-sized meteor entered the Earth’s atmosphere above Lake Ontario and became a bright fireball as it disintegrated. Click here to learn more about this event. Fragments of this “space invader” most likely reached the ground. That same day, at around 11:04 p.m. a similar object was sighted along the east coast from Virginia to Maine. But wait! There’s more. The very next day a previously unknown asteroid estimated to be 187-427 feet across zipped past the Earth at 11:22 a.m., travelling around 45,000 miles per hour. Talk about close encounters!  That one would have wreaked havoc had it collided with the Earth.

    There’s a lot of space debris that the Earth passes through on its journey around the Sun. The vast majority are harmless remnants of comets or small pieces of asteroids. Everyday the Earth is bombarded with this material, and with greater frequency security cameras are recording the demise of the brightest of these visitors to our planet. After careful examination of eyewitness accounts, astronomers can determine the orbit of these bodies and determine if they are associated with a particular meteor shower. Two meteor showers were in progress at the time of the fireball reports. Many folks were lucky to view such a “fiery” display.

    While bright fireballs are chance sightings, you can improve your odds at seeing shooting stars if you can observe a meteor shower from a dark sky location when the event is at its peak activity. During October we are fortunate to have both a minor and a major meteor shower to try our luck.

    First up on the night of October 8-9 is the minor display of shooting stars called the Draconids. This shower currently only produces ten or less yellowish slow-moving meteors per hour. A waxing crescent Moon (First Quarter on the 5th) will brighten the sky somewhat and unfortunately won’t set until about 2:30 a.m. on the 9th.

    However, unlike most shooting star displays, the Draconids are best observed between sunset and midnight when the constellation Draco is highest in the northern sky. All you have to do is find Ursa Major (the Big Dipper asterism). Draco will be above it. While the meteors will emanate from this region of the sky, scan east and west up to zenith (directly overhead). These particles are fairly slow moving, hitting our atmosphere at only 12.5 miles per second. Draco stretches between Ursa Major and Polaris, the pole star, which is the end star in Ursa Minor (Little Bear), the Little Dipper asterism handle. This shower of particles is debris shed by periodic Comet 21 P/ Giacobini-Zinner. As the night progresses watch the northern sky rotate around Polaris. By morning twilight, Draco’s head will be sitting due north about 20 degrees above the horizon.

    The major meteor shower of the month is the Orionids on the night of October 21-22 when the Earth passes through the remnants of Halley’s Comet. While the Orionids are generally a decent shooting star display producing a peak rate of about 20 or so yellow and green meteors per hour between midnight and dawn’s early light, a bright last quarter Moon residing in the nearby constellation of Cancer will certainly reduce that forecast number. Moon rise is at about 11:00 p.m. on the 21st, so it will be overshadowing all but the brightest of the meteors, though a few can be observed before the moon rises. As an added bonus, please notice the cluster of stars to the Moon’s upper right—it’s the Beehive Cluster. Use binoculars for an enhanced view.

    The meteors appear to radiate out of the sky just above Orion’s head (hence the name of the shower) and not far from the bright red super giant star Betelgeuse, which marks his right shoulder. The Orionid meteors disintegrate in our atmosphere around 41.6 miles per second, and they are also noted for producing fireballs that create persistent dust trains as they blaze across the sky. This redeeming attribute could mitigate the Moon’s interference somewhat. While Orion is an easy star pattern to identify, at 3:00 a.m. this giant constellation will be found high in the southeast sky.

Region of the sky to watch for Orionid meteors.

    Try to observe from a dark-sky location if you can. Also try to block the Moon from view as well. Get comfortable in a chaise lounge chair. Settle in for a couple of hours of observing. Hopefully there will be a few bright fireballs to keep you from falling asleep! All you’ll have to do to maximize your viewing experience is to find a suitable location well away from light pollution.

    Don’t forget to visit the local Rhode Island observatories to get great views of the heavens. Jupiter and Saturn will still be visible in October. Seagrave Memorial Observatory in North Scituate is open every clear Saturday night. (Note: Seagrave will be closed on Saturday, October 5.) Ladd Observatory in Providence is open every Tuesday night. The Margaret M. Jacoby Observatory at the CCRI Knight Campus in Warwick is open every clear Wednesday night. Frosty Drew Observatory in Charlestown is open every clear Friday night. Be sure to check their respective websites for public observing schedules and closures, especially since the EEE virus threat may cancel outdoor observing sessions..

    Let’s hope Mother Nature will cooperate to provide us with clear skies for all of our observing adventures.

Solar Variability: Our Inconstant Sun

I went to bed last night wondering where the Sun had gone. Then it dawned on me. A little astronomy humor to begin a serious discussion on our life-giving star—the Sun.

    Our Sun coalesced out of a vast cloud of gas and dust some 100 times the size of our solar system roughly five billion years ago. Gravity contracted this mass until the core of this proto-star reached about 24.5 million degrees Fahrenheit. At that time nuclear fusion began, converting about 600 million tons of hydrogen to helium per second. This process has been ongoing since then.

    Most folks take for granted that the Sun rises and sets every day due to the Earth’s almost 24-hour rotation. The only change most people recognize is the seasonal cycles caused by the fixed 23.5 degree tilt of our planet’s axis in its orbital path about the Sun. Reference this video to refresh your memory on the Earth’s annual journey.

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Poor Prospects for the Perseids

    While the Geminid meteor shower of mid-December reigns supreme as the northern hemisphere’s most productive display of shooting stars, August’s Perseids, coming in a close second,  are the most widely observed meteor shower of the year. Why? Warm temperatures find families spending more time outdoors during the summer season enjoying cookouts, camping, or any other assortment of late evening activities. Normally 60+ green, red or orange Perseids can be observed per hour during peak activity. Unfortunately, for 2019 a waxing gibbous Moon (Full on the 15th) will severely hamper observing this meteor shower which peaks on the night of August 12-13.

    However, while moonlight will wash out all but the brightest meteors before midnight on the night of the 12th, once the Moon sets around 3:48 a.m. that will leave just over an hour of dark sky observing time before dawn’s early light begins to brighten the sky. Somewhat helpful is the fact that Perseus, the constellation from where the meteors appear to radiate (known as the radiant point), is completely opposite the sky from the Moon. This circumstance could help extend your window of opportunity to an hour or two before the Moon sets! Hey, I’m trying my best to be optimistic here!!

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Splendid Saturn

    I hope the weather gods have provided a few clear nights since my Jupiter observing guide appeared last month. I finally observed Jupiter at a late June star party Skyscrapers members conducted for the Jesse Smith Memorial Library in Harrisville on June 28. The four Galilean moons were easily visible in all the telescopes, as were Jupiter’s striking banded cloud tops. Regrettably the Great Red Spot was not visible that night, and my attempts to observe it since my last column have been thwarted for one reason or another. Fortunately, we have several more months to glimpse this perhaps dwindling storm.

    I’m sure some of you couldn’t resist an early look at Saturn, even if you had to wait much later in the evening for this beautiful ringed-planet to rise high enough into the sky to clear summer horizon haze. Perhaps sky conditions permitted you to obtain marginal views despite the planet’s low altitude above the horizon within a couple of hours after sunset. Now that another month has passed, Saturn will have risen much higher into the southeast sky, thereby allowing for more favorable views. As promised at the end of July’s column, here is a brief observing guide to Saturn (our solar system’s most stunning planet.)

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The Return of Jupiter and Saturn to the Evening Sky

Jupiter

    Quite a few months have passed since the local observatories have had the opportunity to provide detailed images of some of our planetary companions in the solar system. When weather conditions have allowed, the Moon has been a good substitute. When the Moon has not been available, telescope operators have turned to double stars and faint fuzzies like star clusters, galaxies and nebulae. However, these celestial objects don’t often elicit the wow factor that planetary viewing can do. Add some high thin haze, atmospheric turbulence, a little bit of moisture and light pollution, and it has been a challenge to provide decent views of the heavens. Our observing opportunities have now greatly improved.

    While amateur astronomers have been observing Jupiter and Saturn during hours when most people are in REM dreamland, from now through November telescopes throughout Rhode Island will focus on exquisite views of these two gas giant worlds and all their glory. All I can say is, “It’s about time!!” This month’s column will provide a brief observing guide to Jupiter. Next month I will feature Saturn.

    Back on June 10 Jupiter reached opposition. That means it rose as the Sun was setting. This date was also the date of Jupiter’s closest approach to the Earth for this year—about 397,850,855 miles. By July 1 this distance will have increased to 403,576,313 miles as the Earth pulls out ahead of Jupiter in our respective orbits. Fortunately, views of  the Jovian system do not suffer dramatically from rapidly increasing distance.

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