Maui Astronomy Club

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Waning Crescent Moon
Waning Crescent Moon

The moon is currently in Sagittarius
The moon is 25 days old

Distance: 60 earth radii
Ecliptic latitude: 1 degrees
Ecliptic longitude: 259 degrees

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    Happy Full Moon Solstice June 20, 2016

    Awesome article by Phil Plait.


    On Monday at 22:34 UTC (6:34 pm Eastern U.S. time), the Sun will reach its highest declination in the sky, its farthest point north for the year. That is the moment of the June solstice.

    This means that, in the Northern hemisphere, we have the longest day of the year, and the shortest night. If you live your life standing on your head in the Southern hemisphere, it means you have the shortest day, and the longest night.

    I enjoy writing about the solstices and equinoctes* when they happen, so you can read all about how and why they occur in past articles. I’ll note that Monday is notthe date of the earliest sunrise and latest sunset though; that has to do with the Earth’s orbit being slightly elliptical, so I’ll make a special point of linking to this article last year where I explain why that happens. I’ll also note that some people call this the first day of summer (or winter for those in the south), but I disagree; I tend to think of it as actually the midpoint. You can read about that to your brain’s delight as well.

    Earth tilt animation

    No, instead of spending time on that here, I’d prefer to point out something rather special that led to me wandering down a rabbit hole Sunday night as I researched it: Not only is the solstice Monday, but the Moon is full on Monday as well. That moment occurred at 11:02 UTC (07:02 Eastern; I’ll note it’ll look full all day and probably even Tuesday as well).

    A full Moon on the same day as the June solstice (or the December one, for that matter) is relatively rare. As I thought about this Sunday night, I wondered just howrare it was. My first thought was that it probably happens once every 30 years or so, since the full Moon can occur on any day, and there are 30 in June.

    But then I realized it’s not that simple. Sometimes in astronomy two cycles can beat together in unusual ways, throwing off what you might expect. So I dug into it. I found a list of solstice full Moon dates on the Farmer’s Almanac website, and perusing the numbers it appears that we get a full Moon on the June solstice roughly every 19 years or so … or multiples thereof.

    Nineteen years? That sounded familiar. It took me a few minutes, but then it clicked: That’s the Metonic cycle! Let me explain.

    The Moon goes through a full phase of cycles (from full to new and full again) in about 29.53 days. That all by itself is interesting.

    One Earth year is, on average, about 365.24 days long. But there’s a funny coincidence here: 19 years is 6,939.56 days, and that is almost a perfect multiple of 29.53! Nineteen years is almost exactly 235 lunar phase cycles. That means that when you have a full Moon on a given date, 19 years later it’ll be on that same date once again. That’s what’s called the Metonic cycle. This fact has been known for about 2,500 years, which is pretty amazing.

    But looking at the Farmer’s Almanac, you see it doesn’t seem to happen every 19 years. Why not?

    This is where I really started to dig deep. I looked at leap years, and fractional leftovers between the lunar phase month (called the synodic month) and the Earth’s year, and on and on. That can account for some of the reason the full Moon doesn’t always fall on the same calendar date every 19 years.

    Then I realized something: time zones.

    Astronomical sites list the times of the solstices and full Moons in Coordinated Universal Time (UTC, similar to Greenwich time). That makes it easy for everyone, since you can just look up how far off your time zone is from that (for example, right now the East Coast of the U.S. is on Eastern Daylight Time, UTC – 4 hours).

    But that can mess up the full Moon June solstice cycle. Why? Because the exact moment of the solstice changes year to year, and can even occur on different days! It can be on June 20, 21, or sometimes even 22. If the solstice occurs on June 21 at 23:59, and the full Moon two minutes later, technically they’re on different days!

    Worse, that’s UTC. In the U.S., where it’s four to seven hours earlier than UTC, both would occur on the same calendar day. So it’s possible (and even likely) that one place in the world would see a full Moon on the same calendar day as the solstice, and another part of the world wouldn’t. What a mess!

    Look at Monday’s solstice: It occurs at 22:34 UTC. For someone a couple of time zones east of the U.K., that means it happens on June 21. For them, they don’t get a full Moon on the day of the solstice. The exact moments of the solstice and full Moon are independent of time on Earth (the solstice occurs at the same moment for everyone on the planet, for example), but because we bin time up into days, that can throw off the days on which we say those events happened. Weird.

    Going back to the Farmer’s Almanac, you may notice that while the solstice full Moon doesn’t happen every 19 years, it does appear to have a cycle of multiples of 19. For example, there was one in 1796, then the next in 1834, a gap of 38 years, 2 x 19. Other such gaps can be found. The gaps happen because the full Moon missed the calendarday of the solstice by some hours. Not only that, but that table is for the U.S. East Coast, so it doesn’t work for the whole world.

    The root of this problem is using calendar days, which are arbitrary to some extent. There’s an overall 19-year cycle, but because of time zones it can get thrown off. A better way to do this would be to ask, “How often does a full Moon occur within a day of the solstice?,” or better yet within 12 hours before to 12 hours after the moment of the solstice.

    In that case, I’d expect the 19-year Metonic cycle to be more obvious. However, looking that up using calendars for the full Moon (like this one) and the solstices (like this one) is difficult and tedious. The best way would be to run the calculations specifically looking for that, which I thought of too late to ask anyone to do for Monday’s events. I’ll leave that as an exercise for the reader.

    Anyway, my point is … well, I guess I don’t have a point except that numbers are fun to play with and the cycles in the sky are neither always obvious nor simple to grasp.

    But they’re there, and if a full Moon falling on the solstice is interesting enough to people that they go outside and take a look for themselves, then I’m all for it.

    So happy full Moon June solstice! Enjoy it, because the next one won’t be for a while—June 21, 2062, in fact … if you use UTC.

    *Equinoctes is the actual plural for equinox. Some dictionaries say that’s a bit old-fashioned, and equinoxes is now used, which is fine by me. Languages change over time. But I rather like the way equinoctes sounds, and I like using it. So I do.




    Keeping an Eye on Mercury

    Look outside after sunset.  Face west and see if you can catch a glimpse of cute and quick Mercury!  It will be low in the sky with a beautiful crescent Moon above it.  On May 9, Mercury will pass directly in front of the Sun, called a transit.  In Hawaii, the transit will be in progress at SUNRISE.

    Such a quick moving planet, the ancient people depicted Mercury as the messenger god with winged shoes and a winged helmet!

    Also, tonight’s Moon will display “Earth Shine”……the dimly lit part of the Moon revealing the entire orb.  This is caused by sunshine bouncing off Earth onto the Moon.

    A beautiful sight!  Go see it tonight!

    Earthshine_2005-09-01    Unknown

    2016 Partial Solar Eclipse on Maui!

    Get ready for the March 8, 2016 Partial Solar Eclipse seen from Maui!
    A MUST SEE!   All can come!  Invite as many friends as possible!

    Eclipse begins:   4:35 pm     (Sun Altitude – 26 deg) 

    Max eclipse:       5:37 pm     (Sun Altitude – 12 deg)

    Eclipse ends:      6:31 pm     (Sun Altitude – 0 deg)

    Sunset:              6:33 pm

    Choose from 3 Locations to View Eclipse FREE through a Telescope
    1. House of the Sun (Haleakala) – 4pm – Sunset – arrive early because Solar Telescope guys scheduled wide load transports that may delay viewers 🙁
    2. Kalama Park Kihei – 2pm – 7pm – event hosted by National Solar Observatory and Maui Science Center
    3. Kaanapali, Hyatt Regency – 4pm – Sunset – Eddie Mahoney to provide telescope viewing near pool deck
    Chasing the Eclipse: I hope to set up on Haleakala, but if the weather is not good up there that day, I will chase the eclipse to Kihei…..if Kihei weather is not good, I’ll jam over to Kaanapali…..if Kaanapali has bad weather…..we’re out of luck!

    Planetary Line Up!


    SET YOUR ALARM FOR DAWN: The Great Naked-Eye Planet Show of 2016 is reaching its peak. For the next week, the five brightest planets in the solar system can be seen, all at once, in a great line stretched across the pre-dawn sky. Denis Crute photographed the quintet on Feb. 2nd just before daybreak at Woolgoolga, Australia:planets_strip

    Crute took the picture using a Nikon D5200 digital camera set to ISO 3200 (f3.5) for a 2 sec exposure. Other photographers may wish to note those settings, because there are some excellent photo-ops in the mornings ahead. On Feb. 3rd, the Moon will pass by Saturn in the constellation Scorpius: On Feb. 6thand 7th, the slender crescent Moon will form a lovely shape-shifting triangle with Venus and Mercury.

    Awesome Night with Ron Ghosh, Space Scientist

    Aloha Light Lovers!
    Thank you to those who made it to last night’s gathering on Haleakala and a HUGE THANK YOU to Dr. Ghosh!…….we experienced so much magic…..I don’t know where to begin!
    This was one of the BEST gatherings the Maui Astronomy Club has experienced!
    First when we arrived to watch sunset, we saw the BROCKEN SPECTRE…..a rainbow around our shadow cast into the clouds of the crater!!!!
     It was amazing!
    Wikipedia: A Brocken spectre (German Brockengespenst), also called Brocken bow or mountain spectre, is the apparently enormous and magnified shadow of an observer, cast upon the upper surfaces of clouds opposite the sun. The phenomenon can appear on any misty mountainside or cloud bank, even when seen from an aeroplane, but the frequent fogs and low-altitude accessibility of the Brocken, a peak in the Harz Mountains in Germany, have created a local legend from which the phenomenon draws its name. The Brocken spectre was observed and described by Johann Silberschlag in 1780, and has since been recorded often in literature about the region.
    Then we saw a QUADRUPLE RAINBOW….like the one in this photo!!!   I was screaming with joy!! I had never in my 25 years on Maui seen a quadruple!PastedGraphic-2PastedGraphic-2
    After all our excitement with the rainbows we met the equally exciting space scientist, DR. RON GHOSH!  (in the ball cap)
    Screen Shot 2015-09-23 at 2.46.55 PM
    Wow, Ron is incredible!  We were hanging on every word and could talk with him all night!
    Ron has over 40 years of space experience….he has worked with NASA on many missions,  the Cassini Mission to Saturn to name a few.
    The Messenger Mission to Mercury was also one of Ron’s projects and we learned quite a bit about the secrets of Mercury.
    Ron also supervised the New Horizons Mission to Pluto and was telling us how Pluto’s atmosphere reaches all the way to it’s largest moon, Charon!
    We must have Dr. Ghosh back!  He is fascinating and such an eloquent speaker.
    He’s worked on many other projects including his latest project, Solar Probe Plus mission which will launch in 2018:  it will study the streams of charged particles the Sun hurls into space from an unprecedented vantage point: inside the Sun’s corona – its outer atmosphere – where the processes that heat the corona and produce solar wind occur. At closest approach, Solar Probe would zip past the Sun at 125 miles per second, protected by a carbon-composite heat shield that must withstand up to 2,500 degrees Fahrenheit and survive blasts of radiation and energized dust at levels not experienced by any previous spacecraft.  See more about the mission here:
    During our time stargazing, we saw 2 unidentifiable flying objects (UFOs)  Even Dr. Ghosh was uncertain what they were!
    They were brighter than any star…the brighter one was probably -2 mag. and the other about -1 mag.
    They appeared parallel to each other in the SE part of the sky at about 25 degrees up and did not move like “normal” satellites.
    They seemed stationary and faded after a minute or so.  My husband thinks they were Russian rocket bodies but he can’t confirm it.
    Very cool.  It looked similar to the photo below.j2Lbhk1
    After almost everyone left, a huge fog bank rolled over us and created a DOUBLE MOON BOW!!!! (similar to photo below but a DOUBLE!)
    I couldn’t believe all the magic that happened in just 3 hours!!!!
    Can’t wait to do it again.

    THANKS AGAIN and hope to see you all again next month!

    Becky Sydney
    Maui Astronomy Club

    Astro Talk Friday 9.25.15


    Aloha all,

    We will be holding a public talk this Friday September 25th at 6:30 pm at the Maui IfA in Pukalani (below Longs Drug Store). 
    Our own Sifan Kahale will be talking about ” Pan-STARRS Operations Using Avatars In The Virtual World”.

    “I will spend an enjoyable hour “exposing” the other half of our audience that attends our public talks:  the avatars in the virtual worlds like Second Life.  Also, using virtual models of the Pan-STARRS observatories, I will go through the process of preparing our observatories for nightly operations and demonstrate how we find asteroids and near-Earth objects (NEOs).”

    For more information please email me or go to:

    Live streaming will be available at:


    Dr. J. D. Armstrong
    University of Hawaii Institute for Astronomy
    34 Ohia Ku Street
    Pukalani, HI 96768

    Farthest Galaxy Detected

    Here’s some cool news from…..

    A team of Caltech researchers that has spent years searching for the earliest objects in the universe now reports the detection of what may be the most distant galaxy ever found. In an article published August 28, 2015 in Astrophysical Journal Letters, Adi Zitrin, a NASA Hubble Postdoctoral Scholar in Astronomy, and Richard Ellis – who recently retired after 15 years on the Caltech faculty and is now a professor of astrophysics at University College, London – describe evidence for a galaxy called EGS8p7 that is more than 13.2 billion years old. The universe itself is about 13.8 billion years old.

    Read entire article:

    Astro Talk Tonight! 8/28/15


    Aloha All,

    Apologies for the short notice.  We will be holding an astronomy public talk this Friday August 28th at 6:30 pm.  I will be giving a talk entitled, “Twinkle, Twinkle Little Star, How Do We Know What You Are?”  The talk will be held at the Maui Institute for Astronomy.

    “How we know something is perhaps as important as what we know. We know that stars are distant objects similar to the sun. How do we know that? In this talk you will take a journey to the stars. We will pay particular attention to the way we get there.”

    For more information please email me or go to:

    Hope to see you there.

    Dr. J. D. Armstrong
    University of Hawaii Institute for Astronomy
    34 Ohia Ku Street
    Pukalani, HI 96768