February 4, 2018

The recent lunar eclipse made me wonder what has happened to sensibility. I’m all for people learning about the night sky, but the comments I saw on social media were disheartening. Worse, many in the astronomical community were guilty of overhyping what shouldn’t need to be hyped in the first place.

The recent total lunar eclipse was one of eighteen occurring in the 20 year period 2001-20, so while these aren’t common, they aren’t rare, either.  The total minutes of all these eclipses is nearly 1300, so if one happens to see a total eclipse, one will see it for a period of many minutes, sometimes more than an hour, unlike total solar eclipses which last fewer than 7 1/2 minutes, and in all of our lifetimes under six minutes, assuming one is in exactly the right place, and I mean exactly.  For a lunar eclipse, being in the right place is on the night side of the Earth, which has a probability about one half.  For a total solar eclipse, the probability is 0.5% just to be on the track, let alone in the right place.  The Europeans and Asians will see a total lunar eclipse in July, and all of North America next January.

What bothered me was the blue, super, and blood appellation, along with “the first in 150 years.”

Some background: back on June 5, 2012, when there was a transit of Venus across the Sun, I showed it to a small group of people at the Pima County Medical Society’s office in Tucson.  One individual commented that it was not very interesting, seeing the small dot of Venus against the background of the Sun, 30 times the diameter of Venus, viewed from the Earth.  To me, this was an exceptionally rare event, which last occurred in 2004, and before then in 1882. The next will be in 2117.  The rarity,  the history of those who traveled great distances to see one, the fact that I was following in their footsteps were all important to me.  Others don’t see the world (or other worlds) the way I do, however, and I accept that.  The total solar eclipse last summer was a yawner for a few of my friends, although I actually convinced my brother to take the effort to see it, and he was not at all disappointed.  The next solar eclipse to touch Oregon will be October 5, 2108, and barely reaches the Pacific coast. This past lunar eclipse lasted 76 minutes, which was worth mentioning; I’ve spent fewer than fifty minutes under the Moon’s shadow during the 17 total solar eclipses I have seen.

A blue Moon is when a full Moon occurs twice in one month.  It’s a calendar phenomenon only. Between 2001 and 2020, nine occur.  The exact dates differ, because of time zones, where the full Moon may occur a calendar day later in the eastern hemisphere.  We have two blue moons this year, which is unusual, and yes, it is interesting, but it isn’t the stuff of which “I have to see this or I am missing out on something special and not likely to happen again.”

Supermoons are when the full Moon is relatively close to the Earth.  Because of the shape of the Moon’s orbit and the behavior of the Moon, our satellite can be full and be within 360,000 km of us, one definition of a supermoon, at least twice and maybe three times a year.  That’s like giving an gold star for attending class.  The full Moon of New Years’ Day was actually 2500 km closer to us than this one.  “Supermoon” is a recent term, dating only about three decades.  Before then, we just admired full moons and did just fine.  In part, the “horizon effect,” where seeing a full Moon rise against the horizon, something to compare it with, makes the moon appear large.  It actually appears larger six hours later, when highest in the sky, because we are no longer looking at the Moon across the radius of the Earth but directly at it, 6500 km closer, give or take. I have had almost no success, either as an astronomy columnist or as an amateur astronomer, convincing people that rising full Moons are not unusually bright.

Then again, once I failed to convince a couple that the large red object that was a lunar eclipse wasn’t Mars.  And when I was a kid, I called the crescent Moon “Venus,” because I had recently learned Venus can show phases.  But unlike the couple I learned to change my mind in the face of convincing evidence–and appropriate public shaming.

A supermoon is about 0.28 magnitude brighter than a regular full Moon.  Magnitudes are listed where negative means brighter; every 5 magnitudes is 100-fold difference in brightness.  This translates into a supermoon being  a quarter brighter than average, but brightness is relative.  We don’t compare full moons that we see with other full moons unless we use a light meter.  We usually compare them to what we have recently seen, like how the Moon appeared the night or two before full, also bright.

Still, full moons are special, 11 times brighter than a half moon and 10% brighter than the Moon the day before or day after.  The apparent size of the Moon is larger, but again, without comparison to other full moons, such as photographically or in an eyepiece of a telescope in which one can calibrate size, is not appreciably different.  One way to prove this is to look at a rising full Moon through a cardboard tube and then look at it high overhead.  The size is the same to one’s eye.

The blood moon is a reference to the red color of the eclipsed Moon, because the only light that can reach the eclipsed Moon is from the red sunrises and sunsets around the eclipsing Earth.  As Fred Espenak, “Mr. Eclipse,” put it, “people have been calling these lunar eclipses for two thousand years.”  Of the three terms, replacing blood moon with “eclipse” would have been the most helpful.

There are many astronomical events every year.  In my opinion, they don’t need to be hyped.  There are many beautiful things above, on, and below the Earth, and they are there for those who want to look.

Next time around, my self-improvement goal will be to discuss the phenomenon without raising my voice.  THAT would be a rare event.


Total lunar eclipse 27 September 2015, White Bear Lake, MN. The darkest part is the Moon that is deepest in the Earth’s shadow; the lighter is in the outer shadow.


Transit of Venus beginning, 5 June 2012, Tucson, AZ



November 22, 2012

This eclipse was not going to be a high probability one to see on the continent.  Saros 133, which is the name of this family member, last seen in South America 3 November 1994, would again visit the Earth 18 years and 11 1/3 days later, this time a third of the way around the world, beginning east of Darwin, crossing the Gulf of Carpentaria, then Queensland, near Cairns and Port Douglas, before heading out into the South Pacific Ocean north of New Zealand.  One per cent of the Earth would be covered by totality, but only a small part of that one per cent would be visible over land.

Cairns, on the northeast coast, is in the tropics, about 17 degrees South latitude.  The tropics have a good deal of convective rain showers, and Cairns had about a 50% probability of one’s seeing the eclipse.

We wanted to see Australia, and if I saw the eclipse, it would be the seventh continent I had seen an eclipse on and over.  But more importantly, it would be another chance–my thirteenth–to see one of the most spectacular shows in the world.  We eclipse chasers are addicted to the sight.

We flew to Melbourne, stayed there for 2 days, getting to know the city, and meeting up with two friends from Germany, one of whom I had met before at the last eclipse, over Patagonia, Argentina, 28 months earlier.  Every eclipse, I meet people from prior eclipses, and this one was no exception.

We then flew to Ayers Rock (Uluru) by way of Alice Springs, and visited the monolith at sunrise and sunset, along with a walking tour, so we could see the caves, the petroglyphs, the sandstone, appreciating that for 60,000 of the 350 million years, people have marveled at this place, making it a sacred spot.

We then left, and flew to Cairns by way of Alice Springs again, this time having time for a tour of the town that is virtually in the center of the continent.

The following morning, Cairns was cloudy, except for a nice hole in the sky, that would have been 15 minutes late, had the eclipse occurred that day.  We went out to Green Island, noting that it seemed to be clearer, although the locals said that it had a similar climate to Cairns.  But it didn’t.  Cairns is deeply recessed from the Coral Sea, with an eastern peninsula that was catching moisture from storms to the south and spilling over those of us in town.

We had decided not to get up at 1 a.m. to go out to Green Island for the eclipse, figuring we wouldn’t have mobility.  The problem was we didn’t have mobility in Cairns, either, to go inland or to Port Douglas, both of which might have been better spots to view the spectacle.

My wife suggested I e-mail meteorologist Jay Anderson, who has achieved fame as an eclipse climatologist and meteorologist.  I have been on several eclipses with Jay, knew he was on a cruise ship for this eclipse, but figured he wouldn’t have time to write me back.  Still, what did I have to lose?

As it turned out, it was the best decision I made during the trip.  Jay gave me a weather synopsis and said succinctly at the end of his e-mail:  “If you can, get offshore.”

In the meantime, I met two Russian friends.  Sergey and Tatiana were at the annular eclipse in Kenya in January 2010.  Sergey works for an oil company in Luanda, Angola, and Tatiana is a travel agent in Slovenia.  Sergey was also at the annular eclipse in the US last May, and we saw it together in Page, Arizona.  Sergey was doing automatic eclipse filming, using programs that were far beyond my comprehension.  He was going to stay on land and hope.  Tatiana would do the same, and she had to fly out of Cairns about 2 hours after totality.  Cairns was flooded with eclipse chasers for several days.

So, at 1 a.m. on 14 November, eclipse day, we awoke and caught the 2:30 a.m. boat to Green Island, setting up on the northeast beach at 3:30.  The sky above us was clear, and darker clouds were behind us, back towards Cairns.  It was easiest the clearest skies we had seen so far on the tirp.  We had great views of the Southern Cross, the Magallenic Clouds, alpha and beta-Centauri, and upside down Orion.

There were clouds on the horizon, but we could see sunrise, and first contact, where the Moon begins to cover the Sun.  As the Sun rose, the clouds increased, and so did the tide, which was due to rise 3 meters 2 hours after totality, at 6:38.  We figured we were safe from the tide, but it rapidly appeared that this would not be the case, so we moved well up on shore.

As the Sun rose further, the clouds began to become a little larger and darker–typical convection in the tropics.  We saw several clouds–one in particular–that were worrisome, when we were only 7 minutes from totality.  But then convection shut down due to atmospheric cooling of 3.5 C from the eclipse itself.

This eclipse had a wonderful diamond ring at both ends (do any not?), with a very delicate corona extending about two solar diameters to the east of the Sun.  It was not a dark eclipse, and there was little red along the horizon, but like the family member I saw in Bolivia, the shadow was visible in the morning sky.  Trees on Green Island prevented us from seeing the shadow arrive, but I had no difficulty seeing it depart.  And two minutes later, the eclipse was over, just like that.

Easily three hundred people saw this from the end of Green Island.  There were experienced chasers and many first timers.

Every eclipse is different, but it is difficult to say whether one is more special than another.  Each person sees something a little different, and each person who is fortunate enough to have seen more than one sees something different.  I try to go through a checklist of things to see with each eclipse, but like my camera and video plans, it usually is forgotten at the critical moment, which lasts on average of 2 minutes, but feels like 8 seconds.  We are left asking….”When is the next one?”  It will be 3 November 2013 in the South Atlantic, ending in Ethiopia.  Getting to that one will be difficult….but not impossible.  We have a connection in Africa–Sergey–who has been to Kampala three times and thinks Uganda is a decent possibility to see 24 seconds of totality–yes, 24 seconds–next year.  We discussed the trip, and several other eclipses coming up, including the long-awaited 2017 eclipse in the US, when we met at Sydney a few days later.

Fifteen seconds of fame:  I was interviewed by Australian TV after the eclipse, while on the boat back from Green Island.  I have no idea if anything appeared on TV.  And while lying in bed that night, I got a call on my cell phone beginning with “44” .  A journalist from CNN in London wanted to interview me about my experience, that I published on CNN iReport.  What is interesting–and discouraging to me–about iReport is that most of the featured pictures were of the crescent Sun.  Few showed the total eclipse itself, which is far more beautiful.  Indeed, the difference between totality and a partial eclipse (even 99%), is the difference between day and night.

Eclipse families:

Currently, there are 13 total eclipses in every 18 years 10 or 11 1/3 days, depending upon leap years and time zones.  Each one of the 13 total eclipses is a member of a family that begins at either the north or south poles and moves the opposite direction over nearly 1300 years or 70-75 eclipses.  Some of these start off as total; most begin as partial, become total or annular for many “visits” and then end as partial.

The reason for this repetition is the 3 requirements for a total eclipse:

Synodic period–New Moon–every 29.530589 days.  The Moon has to be in line with the Earth and Sun.                                                    223 New Moons = 6585.3213 days.

Draconic Period–every 27.21222 days.  The Moon’s orbit is inclined 5.1 degrees to the plane of the Earth’s orbit, and the nodes, where it crosses the Earth’s orbit, are constantly moving.  The Moon has to be near a node when it is new.  This particular eclipse was near the ascending node, where the Moon was near crossing the plane of the Earth’s orbit.                                                  242 Draconic periods=6585.3572 days.

Anomalistic period–every 27.554550 days.  The Moon and Sun are nearly the same angular size in the size, but the Moon’s size can change 12% from our view depending upon whether it is near the Earth or far from it.  The Sun-Earth distance changes about 3% every year.  The Moon has to be close enough to the Earth to appear larger than the Sun.                                                                    239 Draconic periods=6585.5376 days.

The first two determine a central eclipse, where the long axis of the Moon’s conic shadow reaches the Earth.  They occur every 6585.3213 days.  Eighteen years are 6570 days, and 4 leap years, or 5, make the period between successive eclipses in a family 18 years and 10.32 or 11.32 days.  The third of a day is important, because it shifts the path of the eclipse about a third of the way west around the world. This eclipse was seen in South America in 1994 and Australia in 2012.  It will be seen in the South Atlantic and Africa in 2030.

While the periods are almost alike, they are not exact.  There is a 0.03 day difference.  This seems minor, but over time, the Moon arrives at the node 2 hours later each cycle.  The Moon doesn’t have to be exactly at the node for a total eclipse to take place, but eventually, the Moon will arrive too late and the eclipse will not happen.

This particular Saros, 133, is an ascending node eclipse that began in 1219 and had its first total eclipse near Prague in 1544.  In the 19th century, it generated eclipses greater than 6 minutes, long for an eclipse.  In 1850, an eclipse was 6m50s, the longest this particular Saros would generate, and it occurred in the eastern tropical Pacific Ocean, north of the equator.  The last total eclipse of this family will be in 2373, and the last eclipse of the Saros will be in 2499.    Because these cycles are not perfect in their lining up, eventually the Moon will miss the node when new, and the eclipse family will die.  But at the same time, one new one will reach the node at the right time, and a new Saros will be born.  I find the workings of the Saros cycle as beautiful as the sight I saw from the Great Barrier Reef last 14 November.


December 30, 2009