The Dog Days of Summer

The Dog Days of Summer

We are clearly in the dog days of summer now. Sunny hot day follows sunny hot day, interrupted by only the occasional late evening thunderstorm. The dog days of summer get their name from the ancient Romans, and before them, the Greeks. No, they are not called the dog days because they ‘aren’t fit for a dog’. They are called the dog days because the hottest part of the summer coincides with the heliacal rising of the star Sirius, also known as the dog star.

That's Sirius on the bottom right - just above the horizon. Sirius is the brightest start in the sky. Photo by Luis Argerich via Flickr.
That’s Sirius on the bottom right – just above the horizon. Sirius is the brightest star in the sky. Photo by Luis Argerich via Flickr.

“Heliacal rising?” you ask. Heliacal rising means that a star (Sirius, in this case) rises just before the sunrise, early enough to be visible. Before the date of a star’s heliacal rising, it rises too late in the morning to be visible to the human eye, it’s light is blocked out by the much brighter light of our sun.

The ancients watched the stars closely. They paid attention to heliacal risings and other astronomical conjunctions. In his book, How We See the Sky, astronomer Thomas Hockey writes, “Imagine watching morning after morning for a favorite bright star. Then, one special morning, you can see it-but only for an instant because soon thereafter, as the sun gets higher in the sky, twilight gives way to daylight and the star (like all stars in daytime) disappears from view. You have witnessed the heliacal rising of a star.”

The ancients not only noticed sky events like heliacal risings, they attempted to draw connections between astronomical and Earthly happenings. As a Mediterranean agricultural people, the Romans saw the supposed effects of Sirius’s heliacal rise to be quite negative. Drought, extreme heat, wilted crops, plagues, and madness were attributed to Sirius’s evil influence.

Here in Minnesota, the dog days of summer are much more tolerable. Drought is rare. The temperature seldom breaks the 100 degree Fahrenheit mark (only about 20 percent of summers in Minnesota see a 100 degree plus day). Summer flowers are in bloom-finally breaking up the mostly green curtain of late spring and early summer.  Bees and butterflies abound in our pollinator garden.

Summer flowers in full bloom.
Summer flowers in full bloom.
Junior botanist
Junior botanist

Rather than straight up heat, we experience occasional high humidity here during the dog days, which can make even relatively mild temperatures quite uncomfortable. Meteorologists refer to the combined effects of heat and humidity as the heat index. Temps in the 90s combined with high humidity produce heat indexes of well over 100 degrees. In 2011, an excessively humid day in Minnesota led to a record setting heat index of 134 degrees in Moorhead, MN. Strange as it might sound, Moorhead was actually the hottest place in the U.S. that day.

Kicking back poolside.
Kicking back poolside.
Digging some sand.
Digging some sand.

But, for the most part, the dog days of summer in Minnesota are mild, sunny, and beautiful. People from all over the Midwest head to Minnesota to spend their vacations at our many lakes.

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At our house, we are enjoying the long, lazy, unscheduled dog days of summer. Daily morning walks, bike rides, eating fresh produce from our garden, splashing about in the kiddie pool, and digging in the sandbox. Summer is short in Minnesota and I try to forget the haste with which brisk autumn winds follow the dog days here. Instead, I focus on absorbing all the sunshine and simplicity that these warm days have to offer.

Feature image of the dog in the pool by Matt Deavenport via Flickr


The Full Buck Moon

The Full Buck Moon

This year, July is ushered in by a full moon. July’s full moon has a number of different names attached to it by the indigenous tribes of North America. American Indian moon names are typically descriptive of seasonal happenings that occur around the time of the full moon. So, the July full moon was known by some tribes as the Buck Moon, because in July male deer (bucks) began to regrow their antlers. The family and I actually spotted a couple of deer today while out walking in the woods, though they scampered back into the brush before I had a chance to see whether they had any small, velvetty antlers emerging from their noggins.

Look at this cutie.  Photo by Larry Smith via Flickr.
Look at this cutie.
Photo by Larry Smith via Flickr.

Another name attached to the July full moon is the Thunder Moon, as frequent thunderstorms appear at this time of year. Here in southern Minnesota, we receive on average 40 or more thunderstorms each year, many of them in July. While most tornadoes occur earlier in the spring here, July can bring thunderstorms which carry the risks of flash flooding and damage from straight line winds. For example, on July 23, 1987 Minneapolis received a whopping 9.15 inches of rain in just six hours, setting a state record for one-day precipitation. This followed another storm just 72 hours earlier that dropped 4 to 9 inches over the same area. This deluge caused massive flash flooding throughout the region. In Minnesota Weather Almanac, meteorologist Mark Seeley writes, “Roads became rivers; storm sewers spouted like geysers. All Twin Cities watersheds flooded.” Thunder Moon seems apt.

Another name I saw commonly listed as a July moon name is “Hay Moon”. July is the month in which hay is ready for harvest – to be cut, dried, and stacked. I can’t think of this process without recalling Tolstoy’s Constantine Dmitrich Levin at work in the hayfields beside his serfs:

“He thought of nothing, wished for nothing, but not to be left behind the peasants, and to do his work as well as possible. He heard nothing but the swish of scythes, and saw before him Tit’s upright figure mowing away, the crescent-shaped curve of the cut grass, the grass and flower heads slowly and rhythmically falling before the blade of his scythe, and ahead of him the end of the row, where would come the rest.”

Harvesting Hay Camille Pissarro [Public domain], via Wikimedia Commons
Harvesting Hay
Camille Pissarro [Public domain], via Wikimedia Commons
One element of the name “Hay Moon” gives me pause, however. While many American Indian tribes were productive agriculturists, hay is not a crop that I associate with them. Hay is grown is used as fodder for livestock, which American Indians didn’t keep. I’m thinking this moon name must have either arrived with European agricultural techniques or, perhaps, was a name never used by American Indians at all.

In Minnesota, we have very short summers. The old joke goes, “Sometimes summertime in Minnesota falls on July Fourth, and sometimes it comes on another day.” The beginning of June is often still chilly, and the last week of August may bring harbingers of fall. But, July! It’s really summertime! If you are an American schoolkid, last school year was a distant memory and the next isn’t even on your horizon yet. When recalling the Julys of my childhood, I think of fireworks, running through sprinklers, popsicles, cook-outs, swimming in lakes, and camping. Classic Midwestern American summer. I think I’d call July the ‘Water Moon’, because of all the lazy summer days spent in lakes and pools.

My kiddo enjoying the season of the Water Moon at the local creek.
My kiddo enjoying the season of the Water Moon at the local creek.

I’ll end with a surprise twist…July 2015 actually has two full moons. That’s right. One tonight on the first, and a second on the 31st. The second one goes by another name…a blue moon. I’ll write about that later this month!

So, how are you spending your July? Scything any hay? What name would you give to the July full moon based on your location and lifestyle?

The Vernal Equinox

Equinoxes occur twice a year, once in the spring (the vernal equinox) and once in the fall (the autumnal equinox). On the equinox, the number of hours of day and night are equal over the entire Earth. So, on the equinox northerly Barrow, Alaska (71°N), equatorial Bogota, Colombia (4°N), and Dunedin, New Zealand (45°S) all receive about 12 hours of daylight and 12 hours of night. If we flash back to the most recent solstice (December 21, 2014), we can see how different these times were. On the last winter solstice, Barrow received zero hours (or seconds!) of daylight. Poor Barrow. Bogota received 11 hours and 51 minutes of daylight (daylength varies little throughout the year near the equator). And Dunedin received a pleasant 15 hours and 44 minutes of daylight – the northern hemisphere’s winter solstice being the southern hemisphere’s summer solstice. So, while there was a great deal of variation between these locales on the solstice (nearly 16 hours from north to south), they all receive about the same amount of daylight on the equinox. 

 The vernal equinox is considered the first day of spring. While first signs of spring may vary based on your locale, this designation makes sense astronomically. The Earth doesn’t orbit the sun in a straight up and down alignment; it is tilted on its axis – this is why we have seasons. From a northern hemisphere perspective, during our winter the northern hemisphere is tilted away from the sun. During our summer, the northern hemisphere is tilted toward the sun. On the equinox, the celestial equator (the Earth’s equator projected out in space) passes through the center of sun. Which means, that neither the South nor North Pole are tilted away from the sun, so all parts of the Earth receive the same amount of sunlight. So, the moment before the equinox, the northern hemisphere is still (just barely) tilted away from the sun. The moment after the equinox, the northern hemisphere is now (just barely) tilted toward the sun. Thus, astronomically, the seasons have changed. The equinox marks the beginning of spring and spring will continue until the summer solstice (June 20-21). On the summer solstice, the northern hemisphere is tilted the most toward the sun it will get, so we receive the most amount of sunlight on that day. After the summer solstice, the northern hemisphere is starting to tilt away from the sun little by little until we reach the next equinox, and then the winter solstice, when we will start to tilt back toward the sun again.

If you are having trouble wrapping your mind around this, I found this video extremely helpful. I posted it here before. It really makes the whole concept much clearer to me. 


 As with the solstices, cultures throughout the world have celebrated the equinoxes for millennia. The Mayans built El Castillo at Chichen Itza around 900 A.D., where on the equinoxes, observers can see a huge shadow depicting the body of a wriggling serpent rise up along the stone wall. 


 A simple equinox celebration:

In much of the world, the new year is celebrated close to the winter solstice. This new beginning is often celebrated by making resolutions. People are filled with intentions of turning over a new leaf and beginning again. To me, this seems out-of-sync with the world around us, however. While sun is gradually returning to the land, we don’t see fresh starts or literal ‘new leaves’ around us (especially in places with cold winters). At the vernal equinox, however, the world is full of new beginnings. The snow is melting, buds may be forming, daffodils and tulips popping up through warming soil, and if not yet – they will be soon. I think this is a more appropriate time to think about starting fresh and new, leaving behind the old and opening yourself to the new.

Consider what has been holding you back or what has been keeping you down. What narrative have you carried with you through the winter that you are ready to let go of? Write it down on a piece of paper and take it outside to burn (safely) on your patio, in your firepit. Let it go; you don’t need to carry it with you any longer. Make room for fresh, new growth.

Why isn’t the Solstice the Coldest Day of the Year?

cold as ice by matthias klaiber via flickr
cold as ice by matthias klaiber via flickr

After I wrote about the winter solstice back in December, I got to wondering why the solstice isn’t typically the coldest day of the year. Since we get our heat from the sun and on the winter solstice we receive the fewest hours of sunlight, why does the coldest day on average occur almost a month later (at least here in Minnesota – this map shows average coldest day across the US.)? On January 21st, we receive almost forty more minutes of sunlight then we do on December 21st, so why is January 21st on average the colder of the two days?

The answer is actually quite straight forward. It takes awhile to warm up! Technically, this phenomenon is known as the lag of the seasons. There are a few forces at work. First, the oceans and ground absorb heat from the sun. They are still hanging onto (and releasing) some of the heat they gathered up over the hot summer months into December. As we move past the solstice, deeper into winter, the amount of residual heat has decreased, so even though we are getting more sunlight, the temperatures still continue to drop.

One apt analogy is a tea kettle on a stove top. When you place the tea kettle on the stove and light the burner, it takes awhile for the water to absorb the heat. The water won’t be hottest thirty seconds after you turn in on, even if you’ve turned the burner all the way up; it takes some time for the water to warm up. Inversely, if after you have heated the water all the way up (this would be July or August on Earth) and then you turn the burner down to low, the water won’t be immediately cool. It will take some time (until January) to cool down to the minimum temperature.

Since the ocean is efficient at retaining heat, this is why some places along the ocean experience less seasonal change than one might expect given their latitudes. For example, London (51 degrees N) is farther North than Minneapolis (44 degrees N), but the average temperature of London in the winter is much warmer than in land-locked Minneapolis. Additionally, the average monthly temperatures in Minneapolis vary by 61.7F, while in London monthly temperatures vary by only 24.3F. The North Atlantic Current brings warm water up to London from the Gulf of Mexico. This water retains much of its warmth during its long Tranatlantic voyage into northerly latitudes, thus keeping temperatures in London much warmer than one would expect given the city’s latitude.

Another factor that slows down warming in the winter is snow cover. When the solar heat emitted by the sun is retained by the Earth, it leads to greater warming. However, abundant snow cover reflects the solar heat back into space, so that we don’t feel its full warming effects. This is like wearing a white t-shirt on a hot day in an attempt to stay cool. So, in the months with the most snow cover (December – February), solar heat retention is reduced.

This year in Minneapolis, we may already have our coldest day behind us. We had a stretch of several sub-zero days at the beginning of January, with a low of -11F on January 5th. Now, we are in the midst of a warming trend. We enjoyed a balmy 37F, sunny day today and we broke out the sleds and skis. It can’t last though, February will bring more cold weather, but hopefully we’ve seen the bottom and are on a (slow) path toward spring weather.

The Winter Solstice

Winter Sun by NietNagel via Flickr

December 21st is the winter solstice in the Northern Hemisphere. It is the shortest day of the year and, correspondingly, the longest night. On the winter solstice, the sun is the farthest south in the sky it will appear and it is the day of the year when the sun reaches its minimum noon altitude. The sun appears to hang at this altitude for a few days, and then turns and begins its journey back northward toward its highest noon altitude – the summer solstice on June 20th or 21st.

These phenomena are more drastic the farther you are from the equator. For example, Bogota, Columbia is just 4 degrees north of the equator. In Bogota on the winter solstice, there will be 11 hours and 51 minutes of daylight. On the summer solstice, Bogota will receive 12 hours and 23 minutes of sunlight. There is only 32 minutes of difference between the shortest day and the longest in Bogota. Let’s compare that to Minneapolis, MN at 44 degrees north. In Minneapolis, we will receive 8 hours and 46 minutes of sunlight on the winter solstice. On the summer solstice, we received 15 hours and 36 minutes of sunlight. So, there is a difference of nearly 7 hours of daylight between the solstices, compared to Bogota’s 32 minutes.

This becomes even more extreme as you go farther north. Let’s head to 71′ N – Barrow, Alaska. The sun will not rise at all in Barrow, Alaska on December 21st. In fact, the sun has not risen in Barrow since November 18. The sun will not rise again until January 23rd, on which day Barrow will receive a welcome one hour and eight minutes of sunlight. They will have gone 65 days since the last sunrise. Conversely, on May 11th, the sun will rise in Barrow at 1:46 a.m. and it will not set again until August 2nd. So, in Barrow, the difference in day length between the winter and summer solstice is 24 hours.

The solstices have been important in human culture for millenia. Imagine yourself living in a world deeply tied to nature and the seasonal cycle. Each day the world has been getting darker and darker. Cold has crept across the land. Nothing is growing. Death and decay seem to be conquering the world. But then, behold! The sun pauses in its sinking journey toward the southern horizon, and it turns back; gradually, the days start growing longer. The cycle of death and rebirth continue once again. This is something to celebrate!

From prehistoric artifacts, we know that the solstices were acknowledged by humans across the world from at least 3200 BCE. Artifacts that show recognition of the solstices have been found across cultures – in Ireland, Indonesia, and Peru, for example. The oldest of these artifacts we’ve discovered comes from Ireland. Just over 30 miles north of Dublin, a prehistoric tomb known as Newgrange overlooks the River Boyne. The tomb was built around 3200 BCE. If you are having trouble placing 3200 BCE in context, this was 500 years before the pyramids were built, a whopping 2400 years before the Greek city states emerged – we’re talking 5000 years ago here.There is a 60 foot passage in this tomb, at the south end of the passage is an opening that the sun shines in only on the winter solstice. On the solstice, the sun illuminates this inner passageway for 17 minutes. You can actually go and visit Newgrange on the winter solstice and witness this phenomenon for yourself, but you’ll have to win their yearly lottery for tickets, as the event is so popular.

Fire is the most wide-spread aspect of winter solstice celebrations. It is easy to see why – what better way to mark the darkest night of the year then by lighting candles and building bonfires? Part of this fire tradition includes the burning of the Yule Log. The roots of the Yule Log are somewhat mysterious, but may have originated in Northern Europe in the 6th century. The Yule Log (perhaps an entire tree in some places) would be burnt on the solstice and should be kept burning throughout the entire night. A portion of the Yule Log would be kept to be burnt in the next year’s fire. On some Yule Logs, a chalk outline of a man was drawn before the log was placed in the fire…perhaps a remnant of human sacrifice made on the solstice?

A simple solstice celebration:

If you would like to celebrate the winter solstice, it is quite easy to put together a simple celebration. I would start by taking advantage of the few hours of daylight that you have on the solstice (unless you are in Barrow, in which case, maybe leave Barrow?) by getting outside. Take your fellow celebrants out for a nature walk in a wooded area and hunt for the perfect Yule Log. What makes a perfect Yule Log? Go with your gut, you’ll know that Yule Log when you see it. Gather your Yule Log and bring it back home. If you have a fireplace, festivities can continue inside, if you prefer. If you are going to be celebrating outside, as the sun is setting (4:34pm here in Minneapolis), get a roaring bonfire going. If you celebrated last year and have a part of the previous year’s log, put that on the fire. Once the old log is burning well, add the new log. When the new Yule Log has just about burnt out, make sure you pull part of it out of the fire to save for next year’s celebration. I love a good poem and a celebration isn’t quite complete without one, in my opinion. As you sit around the fire, have one brave or dramatic soul in your party recite an appropriate poem (there are many). I like this one:

So the shortest day came
and the year died
And everywhere down the centuries
of the snow-white world
Came people singing, dancing,
to drive the dark away.

They lighted candles in the winter trees;
They hung their homes with evergreen;
They burned beseeching fires all night long
to keep the year alive.
And when the new year’s sunshine blazed awake
They shouted, reveling.

Through all the frosty ages you can hear them
Echoing behind us — listen!
All the long echoes sing the same delight,
This shortest day.
As promise wakens in the sleeping land;
They carol, feast, give thanks,
And dearly love their friends, and hope for peace.
And so do we, here, now,
This year, and every year.
Susan Cooper

While it might be traditionally appropriate to keep the fire burning all night long, I’m into sleeping, and it is cold in Minnesota in December. So, I’d recommend putting the fire out when everyone is tuckered. You can bring the party back inside, but – and this is key- don’t turn the lights on. Whatever hours of wakefulness remain should be spent without the use of artificial illumination. How nice to come in from the bonfire and light the house only with candles on the darkest night of the year. What a different atmosphere it will create from the average night! Contemplate the ways that companionship and celebration combat the darkness of the longest night, maybe even more so than the candles and the fire.

If you find the science side of the solstice interesting, you cannot miss the video below. The visualizations are amazing.

Long Night Moon

photo by Sigurd Rage via flickr
Full Moon Over Oak by Sigurd Rage via flickr

At 7:27 on the morning of December 6th, the moon will become, for an instant, full. Then, it will begin its steady process of waning once more toward the new moon. The December full moon has a number of traditional names attached to it. It is variously called the Long Night Moon, the Cold Moon, and the Moon Before Yule.

The Long Night Moon is quite an appropriate appellation for the December full moon. This full moon occurs close to the winter solstice – the longest night of the year. Moreover, because the moon rides high in the sky at this time of year, it is visible above the horizon for most of the night. Here in Minneapolis, the moon rises at 4:23 pm on December 5th and doesn’t set until 7:25 am on the 6th. That is just over 15 hours of full moon; Long Night Moon, indeed! A good night to be a werewolf or just a plain lunaphile like myself!

If you are here in Minnesota, the sky is perfectly clear across the state tonight and the weather is mild (relatively speaking) – step outside and get a glimpse of the Long Night Moon! If you miss it on Friday night, it will look just as full on Saturday night, so try again then!

The Moon Halo

Upon stepping outside this evening, I was greeted by an unexpected sight: a gibbous moon surrounded by a large ring of light. This phenomenon is referred to as a ‘moon halo’. The appearance of a moon halo is purely an optical effect. Moon halos may appear on nights when there are very high thin clouds (cirrus clouds) around 20,000 feet. These clouds are filled with tiny ice crystals. The ice crystals act like prisms refracting and reflecting the light, thereby creating the appearance of a halo around the moon.

There is a folkloric belief that a moon halo is a sign of an impending storm. This actually turns out to be mostly true. While cirrus clouds do not bring rain or snow themselves, they are often the forerunners of the low pressure systems that do bring precipitation. Another belief is that the number of stars within the halo indicates the number of days until the bad weather arrives, though this one doesn’t seem to hold much water, as you might imagine.

The moon halo was an unanticipated and beautiful sight. It is easy to get so involved in our days and busy lives that we miss these little gifts that are all about us if we just take the time to look around (or above in this case). Looking up at the shining halo around the moon tonight, I felt very fortunate to be there to see it and to have the time to stand out in the cold evening with my little son just gazing upward.

I took some bad pictures on my phone that I won’t make you suffer by posting. Fortunately, there are a number of better photos of moon rings available from Wikimedia Commons:

By Radoslaw Ziomber (Own work) [CC-BY-SA-3.0], via Wikimedia Commons
By Radoslaw Ziomber (Own work) [CC-BY-SA-3.0], via Wikimedia Commons
If you’d like to see some very impressive photos of both lunar and solar halos, visit:

When have you witnessed unexpected moments of beauty in nature?