Celebrating a (Solar) New Year

On January 1st, much of the world will be celebrating the new year, but this Friday might be a more appropriate day to celebrate (at least from an astronomical viewpoint).

This Friday (22 December 2018) marks the Winter Solstice, the date on which the calendar changes seasons from Fall to Winter here in Mid-Michigan (and the rest of the Northern Hemisphere).  Winter will officially begin at 5:23 PM EST.

The word solstice comes from two Latin root words sol (sun) and sistere (to stand still).  On the solstice, the path of the sun appears to stand still! 

Assume that you were to awaken every morning before dawn and mark the location that the sun rises on the eastern horizon.  You would notice that the sun does not in fact arise from the same place every day.  Instead it wanders north and south along the horizon, moving north during the Winter and Spring and back south again during the Summer and Fall.  On the Summer Solstice (June 21st) and Winter Solstice (December 21st), the sun ceases to move further along the horizon, appearing to "stand still" before reversing its course the next day.

You have probably already noticed in addition to the location of the rising sun, the length of day and night vary throughout the year.  As the sun progresses south, the day shortens and the night lengthens.  The Winter Solstice marks the shortest day (and longest night) of the year in the Northern Hemisphere.  Here in Mid-Michigan we will mark the date with approximately 8 hours 57 minutes of daylight.  As the sunrise moves back north along the horizon our days will slowly get longer until on the Summer Solstice we will experience nearly 15 hours 25 minutes of daylight.

Why does the sun move and the length of day vary?

It all has to do with a tilt in the Earth's axis.  The Earth rotates on its axis approximately once every 24 hours - giving us the length of our day.  It also revolves around the sun approximately once every 365 days - the length of our year.  If the Earth's axis was perpendicular the plane on which it revolves around the sun, our days would be the same length throughout the year (approximately 12 hours), but the axis is not perpendicular to this plane.  Instead the Earth's axis tilts 23.5 degrees from the vertical.

The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.  As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  When the North Pole is at its furthest, we experience Winter and the Southern Hemisphere experiences Summer.

On two days of the year, the Earth's axis is perpendicular to the plane of its revolution.  On those two days we do experience equal periods of day and night because the sun rises due east and sets due west.  During the rest of the year our hours of daylight vary depending on where the axis is pointed.  During our summer months, the tilt in the axis means that the northern hemisphere is closer to the sun and receives more hours of sunlight.  During the winter months, the reverse is true.  On the Winter Solstice, the North Pole is tilted at its furthest angle from the sun resulting in the shortest day (and longest night) of the year for those of us in the Northern Hemisphere.

Why did I say that the Winter Solstice would be a better day to celebrate the new year?

Tracking the position of the rising sun was among the first astronomical observations.  Many ancient monuments seem to have been constructed as solar observatories, aligned with the locations of sunrise and sunset on the longest and shortest day of the year.  To early agricultural societies especially, tracking the seasons accurately could mean the difference between a bountiful harvest and failure of a year's crops.  The day that the sun "stood still" in its southward journey and then began to return north, bringing more hours of daylight and eventually warmer weather seems such an obvious point to mark the beginning of a new year!

Join me on a hike to celebrate the Solstice!

To celebrate the Winter Solstice, I am leading a nighttime hike at the Chippewa Watershed Conservancy's Sylvan Solace Preserve.  This hike will begin at 7:00PM.  Sylvan Solace Preserve is located on Pickard Road, between Gilmore Road and Littlefield Road, approximately 8 miles west of downtown Mt. Pleasant.

We are doing a nighttime hike because another celestial event lines up with the solstice this year - a full moon.  (Technically the full moon will be on December 22nd, but it will be more than 97% illuminated on the night of the 21st.)  We are expecting light snowfall early in the day - this should brighten up the woods.  Hopefully the moon will peek through the expected clouds and illuminate our hike.  The trails at Sylvan Solace are flat and well-defined making this a great first night hiking experience!  I hope to do the hike without any artificial lights.  Wear warm clothes and bring a headlamp or flashlight just to be safe.

Summer Solstice 2018

The sun rises through the trees about twenty minutes past official sunrise.

If you were to arise at dawn every day of the year and record the point on the horizon where the sun rises you would be able to track the progression from the Summer Solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the position of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year.  These observations were used to plan planting dates for various agricultural crops.
Today the sun reached its northernmost point on the horizon.  Officially, at 6:07 AM EST Spring ended and Summer began in the Northern Hemisphere.  This moment of change is known as the Summer Solstice.  At the same time, the Southern Hemisphere was experiencing its Winter Solstice as their Fall ended and Winter began. The word solstice comes from the Latin words sol (sun) and sistere (to stand still).  On the days surrounding the solstice, the sun appears to "stand still" for several days as it progresses neither north nor south along the horizon. 

Dawn atop Bundy Hill

Today on the Summer Solstice, with the sun at its highest position in the northern sky, we celebrate our longest day of the year.  With the sunrise at 5:58 AM and sunset at 9:24 PM, mid-Michigan will experience approximately 15 hours 26 minutes of daylight today.  By comparison, Christchurch, New Zealand (which is approximately the same latitude south of the equator as Mid-Michigan is north of the equator), will have only 8 hours 56 minutes of sunlight today.

Why does the length of daylight vary at different locations on the globe? 

It has to do with three factors:  rotation, revolution, and a tilt of 23.5 degrees.  The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis rotates around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

At any given time, fifty percent of the earth is in sunlight (Day) and the other fifty percent is in darkness (Night).  However, as previously mentioned, the Earth is tilted on its axis.  Because of this tilt, sunlight does not always strike the Earth at the same angle.  This means that during different seasons different parts of the Earth will receive varying amounts of sunlight and darkness.
As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun. 

A golden glow...

When the North Pole is at its closest, the sun lights a larger portion of the Northern Hemisphere than it does the Southern Hemisphere.  When this happens, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  During our Northern Summer, not only does the sun light more of the Northern Hemisphere, but the sun also lights every Northern Hemisphere location for a higher percentage of the day than a comparable Southern Hemisphere location. 

When the North Pole is at its furthest from the sun, we experience Winter and the Southern Hemisphere experiences Summer.  During our Northern Winter, the sun is striking a larger portion of the Southern Hemisphere than it is the Northern Hemisphere, and consequently the sun lights every Southern Hemisphere location for a higher percentage of the day than a comparable Northern Hemisphere location.  On two days of the year, the Spring and Fall Equinoxes, the sun lights the Northern and Southern Hemispheres equally and the length of day for will be the same for both. 

Waiting for the sunrise atop Bundy Hill

So how did I celebrate the Summer Solstice?  In the oldest way possible, by greeting the rising sun!  I led a sunrise hike to the top of the tallest hill around.  At 1276 feet above sea level, Bundy Hill is the tallest point in Isabella County.  It is has been protected as a nature preserve by the Chippewa Watershed Conservancy since 2016.  Unfortunately, the surrounding forest made it impossible to see the actual sunrise from atop Bundy Hill, but the trip to the top is always worth it.  When the sun finally did get above the trees I was able to capture the photos seen above.

Winter Solstice 2017

An early winter sunrise (2013)

Winter begins tomorrow (21 December 2017) at 11:28AM.

The moment this change of seasons occurs is known as the Winter Solstice.  The word Solstice comes from the Latin words sol (sun) and sistere (to stand still).  Tomorrow the sun will have reached its lowest position in the southern Sky, giving us our shortest day of the year.  On the Summer Solstice, Mid-Michigan received approximately 15 hours and 26 minutes of sunlight.  Tomorrow Mid-Michigan will see only 8 hours and 56 minutes of sunlight, but from now until the Summer Solstice each day will grow longer.

The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  When the North Pole is at its furthest, we experience Winter and the Southern Hemisphere experiences Summer. 

If you were to arise at dawn every day of the year and record at which point on the horizon the sun rises from you would be able to track the progression from the Summer solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the position of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year. 

Happy Summer Solstice 2017!

Wheat ripening on the Summer Solstice

If you were to arise at dawn every day of the year and record the point on the horizon where the sun rises you would be able to track the progression from the Summer Solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the position of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year.  These observations were used to plan planting dates for various agricultural crops.

Today the sun reached its northernmost point on the horizon.  Officially, at 12:24 AM EST Spring ended and Summer began in the Northern Hemisphere.  This moment of change is known as the Summer Solstice.  At the same time, the Southern Hemisphere was experiencing its Winter Solstice as their Fall ended and Winter began. The word Solstice comes from the Latin words sol (sun) and sistere (to stand still).  Today the sun has reached its highest position in the northern Sky, giving us our longest day of the year.  With the sunrise at 5:58 AM and sunset at 9:24 PM, mid-Michigan will experience approximately 15 hours 26 minutes of daylight today.  By comparison, Christchurch, New Zealand (which is approximately the same latitude south of the equator as Mid-Michigan is north of the equator), will have only 8 hours 56 minutes of sunlight today.
 

Field Corn (Zea mays) requires long summer days to grow and ripen

Why does the length of daylight vary?  The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

At any given time, fifty percent of the earth is in sunlight (Day) and the other fifty percent is in darkness (Night).  However, because the Earth is tilted on its axis sunlight does not always strike the Earth at the same angle.  This means that during different seasons different parts of the Earth will receive varying amounts of sunlight and darkness.
 
As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, the sun lights a larger portion of the Northern Hemisphere than it does the Southern Hemisphere.  When this happens, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  During our Northern Summer, not only does the sun light more of the Northern Hemisphere, but the sun also lights every Northern Hemisphere location for a higher percentage of the day than a comparable Southern Hemisphere location. 

When the North Pole is at its furthest from the sun, we experience Winter and the Southern Hemisphere experiences Summer.  During our Northern Winter, the sun is striking a a larger portion of the Southern Hemisphere than it is the Northern Hemisphere, and consequently the sun lights every Southern Hemisphere location for a higher percentage of the day than a comparable Northern Hemisphere location.  On two days of the year, the Spring and Fall Equinoxes, the sun lights the Northern and Southern Hemispheres equally and the length of day for will be the same for both.

Ode' imin Giizis and the Summer Solstice

Today, at 6:34 PM EST,  Spring ends and Summer begins in the Northern Hemisphere.  The moment this happens is known as the Summer Solstice.  The word Solstice comes from the Latin words sol (sun) and sistere (to stand still).  Today the sun has reached its highest position in the northern Sky, giving us our longest day of the year. 

The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  When the North Pole is at its furthest, we experience Winter and the Southern Hemisphere experiences Summer. 

If you were to arise at dawn every day of the year and record at which point on the horizon the sun rises from you would be able to track the progression from the Summer solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the postion of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year.


This year the solstice falls on the same date as the full moon.  This is a rare occurrence - the last such pairing occurred in 1948.  The full moon and solstice occurring within 24 hours of each other is less rare, but still uncommon.  The last time that happened was 1986.

You might hear people referring to this full moon as the "Strawberry Moon".  To Anishinaabe people in Michigan the Strawberry is known as ode' imin (heartberry) and the month of June is known as Ode' imin Giizis (Strawberry Moon).

In honor of the Solstice...

The Shortest Day

Today (21 December) is officially the shortest day of 2015.  Mid-Michigan will only receive 8 hours 55 minutes 23 seconds of sunlight today - or we would if it wasn't supposed to rain all day.  From now until June 21st, the length of each day will lengthen until Mid-Michigan receives 15 hours 26 minutes 57 seconds of sunlight, at which point the length of days will again begin to decrease.  The days when the length of daylight is at its minimum and maximum are known as the solstices.

In honor of the Winter Solstice, the Chippewa Watershed Conservancy scheduled a sunrise walk for this morning at the Sylvan Solace Preserve west of Mt. Pleasant.  Unfortunately, the dreary weather limited interest in the event.  Nevertheless, a small group of four dedicated nature lovers made a walk around the property's River Loop trail. 

Trying to call a late-to-bed Eastern Screech Owl

Checking out a QR code

Observing the Chippewa River

Overcast skies hid the sunrise from view

A White-tailed Deer Skull along the trail

A close-up view of the deer skull

Looking along the River Loop trail

Pileated Woodpeckers have been hard at work

CWC intern Jonathon Breithaupt has an eye for debris

American Beech saplings hold tight to their leaves

A small colorful fungus or lichen covering a dead sapling

Happy Solar New year!

Happy New Year!

No, not the calendar "new year".  Yesterday marked the Solar New Year. 

Yesterday 21 DEC 2014 at 6:03PM Eastern Standard Time, Mid-Michigan (and the rest of Earth's Northern Hemisphere) celebrated the annual Winter Solstice.  On our current calendar the Winter Solstice marks the end of Fall and the beginning of Winter.  Many ancient societies (in the Northern Hemisphere) marked the Winter Solstice as the beginning of a new year.

The word Solstice comes from the Latin words sol (sun) and sistere (to stand still).  Yesterday the sun will have reached its lowest position in the southern Sky, giving us our shortest day of the year.  On the Summer Solstice, Mid-Michigan received approximately 15 hours and 24 minutes of sunlight.  Today Mid-Michigan will see only 8 hours and 58 minutes of sunlight, but from now until the Summer Solstice each day will grow longer.

The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  When the North Pole is at its furthest, we experience Winter and the Southern Hemisphere experiences Summer. 

If you were to arise at dawn every day of the year and record at which point on the horizon the sun rises from you would be able to track the progression from the Summer solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the postion of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year.

Winter Solstice

It has felt like Winter for several weeks, but Winter officially begins today at 12:11PM EST.

The moment this change of seasons occurs is known as the Winter Solstice.  The word Solstice comes from the Latin words sol (sun) and sistere (to stand still).  Today the sun will have reached its lowest position in the southern Sky, giving us our shortest day of the year.  On the Summer Solstice, Mid-Michigan received approximately 15 hours and 24 minutes of sunlight.  Today Mid-Michigan will see only 8 hours and 58 minutes of sunlight, but from now until the Summer Solstice each day will grow longer.

The Earth rotates around its axis approximately once every 24 hours.  However this axis is tilted at 23.5 degrees from the vertical.  The points on the globe that the axis revolves around are referred to as the North and South Poles.  The axis is always pointed toward the same location in the sky.  The North Pole points toward the "North Star" - Polaris.

As the earth revolves around the sun, sometimes the North Pole is closer to the sun, sometimes the South Pole is closer to the sun.  When the North Pole is at its closest, we experience Summer in Mid-Michigan and the Southern Hemisphere experiences Winter.  When the North Pole is at its furthest, we experience Winter and the Southern Hemisphere experiences Summer. 

If you were to arise at dawn every day of the year and record at which point on the horizon the sun rises from you would be able to track the progression from the Summer solstice (in which the sun rises furthest North) to the Winter Solstice (in which the sun rises furthest South) and back again.  Tracking the postion of the rising sun was one of the earliest astronomical observations.  Many ancient monuments were constructed to act as solar observatories, recording the longest and shortest days of the year.


In honor of the Solstice...

A low winter sun - Chipp-A-Waters Park, Mt. Pleasant, MI