2017, August 21: Safe Solar Eclipse Viewing

Viewing a solar eclipse is always a challenge and potentially can damage eyesight.  The gleaming orb of solar intensity is difficult to look at anytime.  Its intensity normally causes us to look away.  To ensure safe viewing, use indirect methods, such as merely sitting under a tree.  The overlapping branches, naturally produce tiny pinholes.  Under a tree on any typical day, you’ll see patterns of shade and spots of light.  These spots are images of the sun projected on the ground.  During an eclipse, images of the eclipsed sun appear on the ground.

In this image notice the dozens of eclipse images that are displayed on the wood deck.  On a windy day the images dance on the ground as the leaves respond to the changing air patterns.

Even in large group settings, such as schools, these indirect methods give everyone a continuous view of the slowly moving moon across the sun’s face.

In this view a student has made a hole in a paper plate.  When held in sunshine, the plate casts a shadow and a tiny hole in the plate allows the eclipse to project through into the shadow made by the plate.

The famous solar projector made with a box that has aluminum foil that is place over a hole in the box.  Multiple holes in the foil show a solar display.

Any object with multiple holes such as a straw hat (above) or colander will project a pattern of eclipses.

The solar image can be projected through a telescope or binoculars.  Never look through the optical device, even with filters.

In this image the telescope has a white card for projecting the solar image.

Here a projection through binoculars shows two images of the eclipse.

For schools that are in session on eclipse day, show students how to view the eclipse safely.  It would be an ideal time for students to build eclipse viewers, solar cookers and other solar projects so they can be outside to try out their work.

2017, August 21: Chicago’s View of the Great American Solar Eclipse

Solar Eclipse photos from 2012 Annular Eclipse

As an astronomy instructor, I spoke with students about the “solar eclipse in 2017.” Well, it’s upon us.

On August 21, the moon’s shadow races across the United States from the northwest to the southeast, with its path crossing through southern Illinois.  As the moon revolves to the east and passes directly in front the sun, the shadow’s width varies from about 37 miles to 71 miles.  Within this “path of totality,” the moon completely blocks out the sun.  In southern Illinois, the total eclipse reaches 2 minutes, 40 seconds.  Although the entire eclipse process takes nearly three hours.

The images above are from the annular (ring) eclipse from 2012.  During that eclipse, the moon appeared to be too small to cover the sun, as our lunar neighbor was too far away to completely cover the sun.


NASA Photo

For those travelling to locations in the darkest part of the eclipse’s path, they will see a total eclipse with the moon covering the sun, revealing the sun’s corona, commonly known as the sun’s “atmosphere.”  For the scant few minutes, of “totality,” the corona is visible because normally, the glowing face of the sun overwhelms this thin, hot crown of gas.

Viewing the Eclipse From Chicago

Viewing the eclipse is always a challenge and potentially can damage eyesight.  The gleaming orb of solar intensity is difficult to look at anytime.  Its intensity normally causes us to look away.  To ensure safe viewing, use indirect methods, such as merely sitting under a tree.  The overlapping branches, naturally produce tiny pinholes.  Under a tree on any typical day, you’ll see patterns of shade and spots of light.  These spots are images of the sun projected on the ground.  During an eclipse, images of the eclipsed sun appear on the ground.

In this image notice the dozens of eclipse images that are displayed on the wood deck.  On a windy day the images dance on the ground as the leaves respond to the changing air patterns.

Even in large group settings, such as schools, these indirect methods give everyone a continuous view of the slowly moving moon across the sun’s face.

In this view a student has made a hole in a paper plate.  When held in sunshine, the plate casts a shadow and a tiny hole in the plate allows the eclipse to project through into the shadow made by the plate.

The famous solar projector made with a box that has aluminum foil that is place over a hole in the box.  Multiple holes in the foil show a solar display.

Any object with multiple holes such as a straw hat (above) or colander will project a pattern of eclipses.

The solar image can be projected through a telescope or binoculars.  Never look through the optical device, even with filters.

In this image the telescope has a white card for projecting the solar image.

Here a projection through binoculars shows two images of the eclipse.

For schools that are in session on eclipse day, show students how to view the eclipse safely.  It would be an ideal time for students to build eclipse viewers, solar cookers and other solar projects so they can be outside to try out their work.

Chicago’s View

The total eclipse is not visible from Chicago.  The maximum eclipse (amount of the sun covered by the moon) is 87%.  The eclipse begins in Chicago at 11:54 a.m. CDT with the sun high in the southern sky.

At this time, the edge of the moon appears to be touching the edge of the sun.

The moon gradually moves in front of the sun as shown in the chart above for 30 minutes from 12:30 p.m. to 1 p.m.

The best part of the eclipse occurs during the next 30 minutes as the moon reaches its maximum eclipse (87%) at 1:19 p.m.

During the next 72 minutes the moon begins to uncover the sun, with the moon exiting from the sun’s face at 2:42 p.m.

Robert C. Victor’s Eclipse Resources

Robert C. Victor, former staff astronomer at Abrams Planetarium, has provided the following list of resources for those who want further details about the August 21, 2017, eclipse.

Solar Eclipse information and Resources

Future American Total Solar Eclipse

The next total solar eclipse visible in North America is on April 8, 2024.  The moon’s shadow sweeps from the Pacific Ocean through Mexico and into Texas moving rapidly northeast.  It crosses through Southern Illinois into Indiana and Ohio.  Then it moves into New York state and then into the New England states.  It crosses into Canada and into the Atlantic Ocean.  From Chicago 94% of the sun is covered.

Skywatching November 2012

Moon Phases

Last Quarter — 11/06/12
New Moon — 11/13/12 — A solar eclipse accompanies this New Moon, but it is visible in the South Pacific.
First Quarter — 11/20/12
Full Moon — 11/28/12 — A penumbral lunar eclipse is part of this Full Moon.  A penumbral eclipse occurs when the moon passes through the outer part of the earth’s shadow.  Most eclipses of this type are hardly noticeable.  In the Chicago area, the eclipse begins at 6:04 a.m. CST, but the moon sets at 6:50 a.m. CST.  Because the moon is low in the west as the eclipse begins, this is largely a non-event for the region.

The sun continues to rise farther south of east and set farther south of east during the month.  A noon the sun is lower  in the south.  During November, we lose an additional hour of daylight with about 9.5 hours of daylight at month’s end.  Daylight Saving Time ends on November 4 with the return to standard time when clocks are set back one hour.

Evening Sky

Early in the month, Jupiter rises north of east during early evening hours.  It appears in front of the stars of Taurus.  The moon passes Jupiter twice during the month.

The chart above shows Jupiter, Moon, and Aldebaran at 9:30 p.m. CST on November 1.

Later in the month, the moon returns to the Taurus region. On November 27 and 28, as shown in the chart above, the moon is visible with Jupiter and Aldebaran again as the trio are visible in the eastern sky at 6:30 p.m. CST. As the moon and Jupiter rise, the moon is about 1 degree away from the planet.

Throughout the month Jupiter appears to be moving westward (retrograde) as compared to the stars.  The chart above shows Jupiter on November 1, 10, 20, and 30, 2012 as it appears to move backwards.  This retrograde motion is due to the faster moving Earth catching up to and passing Jupiter.  This occurs with all the planets that lie outside Earth’s orbit.  This illusion is most pronounced in the planets closest to Earth (Mars and Jupiter).  When Earth moves between a planet and the sun, we call this “opposition,” as the sun and planet are opposite in the sky.  When the sun sets in the west, Jupiter rises in the east.  Jupiter appears in the sky all night as our planet rotates.  Jupiter reaches opposition on December 3.

Mars is visible low in the southwest, setting before twilight ends throughout the month. On the evenings of November 15 and November 16, the waxing crescent is nearby.  The chart above shows the moon and Mars at 5:15 p.m. CST.  Locate a clear horizon to see the moon and Mars.

Morning Sky

Venus remains the bright starlike object in the eastern sky before sunrise.  This brilliant planet has been in the eastern sky for the last several months.  (See our outlook for Venus as a Morning Star.)  Venus is now rising south of east and continues to rise farther south of east each day.  At the month’s beginning, Venus rises about 3 hours before sunrise and decreases to 2 hours, 24 minutes by month’s end.

The faster moving Moon passes Venus on the morning of November 11.  On this morning Venus and the earth’s nearest celestial neighbor are about 6 degrees apart.  The star Spica is below the pair.

Venus continues its rapid eastward movement, passing Spica, the brightest star in Virgothe morning of November 16. They are separated by about 4 degrees.   Planet Saturn is re-entering the morning sky, after its conjunction with the sun in October, appears below.

Late in the month Saturn re-enters the morning sky and joins Venus .  On November 27, Venus passes Saturn.  Look in the eastern sky during early morning twilight.  Brilliant Venus appears below dimmer Saturn.  The pair are separated by less than 1 degree.  Spica appears above the planetary pair.

Mercury is at inferior conjunction on November 17 and rapidly moves into the morning sky.  The chart above shows Mercury, Venus and Saturn in the eastern sky at 6 a.m. on November 30, 2012.  Locate a view with a clear horizon to locate the planets and the nearby stars.

From the solar system view in the above chart (click the image to make it larger) shown for November 15, 2012, Mercury is nearly between the sun and Earth.  Earth is nearly between Jupiter and the sun.

As the fall season prevails, the diurnal cycle is now dominated by darkness, brilliant Venus dominates the morning sky and joins Mercury and Saturn late in the month.  Bright Jupiter enters the evening sky with an assortment of other bright stars.

Solar Eclipse Adventure 2012

The May 20, 2012 solar eclipse pulled together four individuals who had studied as planetarium interns at Abrams Planetarium in East Lansing, Michigan.  The quartet is dispersed around the Midwest and we decided to travel to Page, AZ to see the eclipse.  My co-traveler was Carl W, a retired college professor.  We met Tim S, a practicing college professor from Michigan, and his daughter Sara.  Mike B, a magazine editor, rounded out our conjunction.  In addition, Mike organized a group of fellow eclipse chasers who travelled with him to Page.  The photo above shows our group as we waited for the event to begin.

In the photo above during the eclipse, Tim poses with a Sun Spotter, that projects the sun for group viewing.

Mike B. also poses with the Sun Spotter.

Before the eclipse, Carl asked that I take him on a tour of my favorite places in Utah.  During the past two decades, I had explored the canyons and arches near Moab with my wife and daughter.   Carl and I met at the Denver airport and headed west.  We paused in Dillon, Colorado as I was scheduled to deliver an online session for a class I was teaching.  Then we glided down the west side of the Continental Divide, headed for Glenwood Springs where we decided to bike Glenwood Canyon, downhill of course.  A service in town rents bikes as well as hauls the bikes and bikers to a drop off near Dotsero, at the eastern canyon portal.

I70 shares the canyon with the bike path, the Colorado River and the train.

At Hanging Lake, we declined the climb to the lake and posed for photographs.  That’s Carl on the left and your scribe on the right.

In Canyon Country, I planned to show Carl three large arches and other easier features in the area.  I explained that I had planned an easy hike, a medium difficulty hike, and a difficult one to the three arches.

One of the easy features is a series of petroglyph panels in the Colorado gorge near Moab, Utah.  They are along the road and marked by obvious signs.  One of the more interesting images is one that looks like a bear.

Corona Arch was the medium difficulty walk, three miles roundtrip.  The arch is up a canyon adjacent to the railroad tracks.  The hardest part of the walk is the first 50 yards and three short climbs near the arch that are assisted by cables and a ladder.

The arch has been the subject of extreme sports folks.  A group was preparing to swing from the arch during the visit.  This video will show you the scale of the arch.

The above video is one of many appearing on the Internet as “extremeis” rush to replicate the swing.

We moved into Arches National Park where we paused for photos at easy pullouts, such as this one where we can see the Three Gossips, Sheep Rock, Court House Towers and other features.  We began to experiment with the panoramic features on our phones with some of the results included here.

The Windows section offered opportunities to view several classic arches that are easily reached through short walks.  The North Window and South Window are shown above.

When the sun is low, the South Window offers a colorful view of Turret Arch.  This image was made on a return visit just after sunrise.

Double Arch is a large arch pair in the Windows section.  It is an easy walk from the parking lot.  This is my daughter’s favorite arch. 

The easy hike was scheduled for Landscape Arch, a 3.2 mile round trip into the Devil’s Garden section of Arches N.P.  The arch is one of the longest anywhere, stretching over 300 feet.  This arch will topple one day.  It measures about six feet at its thinnest.  About 20 years ago, a section was observed falling from the arch’s center.  Not far away, Wall Arch fell August 4, 2008.  Many features in the park show the curves of fallen arches, now without their upper frames.

The challenging hike was to Delicate Arch.  This is a three-mile round trip hike, with a challenging uphill section that lasts about one-third of the trail.  Depending on the position of the sun, the arch shows a multitude of color, especially against the background of canyons and mountains.

Easy views followed.  The above view is from Dead Horse State Park, where the Colorado River makes a sharp turn as it heads into Canyonlands N.P.  The view has been included in many television advertisements.

Next we moved into Canyonlands to the Grand View Point.  The vertical structures in the center of the canyon stand about 300 feet.  One of the visual challenges is landscape fatigue.  All views are spectacular.   The views are so incredible that the next one does not have the impact as the last. 

Next we headed south and paused at the Goose Necks of the San Juan State Park.  Before reaching the Colorado River, the San Juan River makes sharp meanders.

On the road to meet Tim and his daughter at Monument Valley, we stopped to capture some classic views of the region.

Moving to Page, AZ we visited the Glen Canyon Dam that holds back the strength of the Colorado River.  The dam is immediately upstream from the Grand Canyon.  Notice Lake Powell’s color compared to the river photos above.  As the river reaches the lake, the silt it carries is dropped into the lake’s depths and the lake appears deep blue.  I won’t review the environmentalists’ arguments against the dam.  There are many that are counterbalanced by the reality that the mass of concrete blocks the river’s passage.

While at Page, we searched for grassy areas where we could set up out telescopes for eclipse viewing.  Being in the desert, green spaces were difficult to locate.  School grounds and their associated athletic fields were fenced, gated and locked.  We located a small park near a sports facility.  It served us well as can be seen in the photograph at the top of this posting.

Eclipse Day was spectacular.  The eclipse began in late afternoon and the sun set before the eclipse finished.  The image above is a composite showing the eclipse just before the maximum, at maximum, and just after the maximum phase.  The eclipse was an annular eclipse.  For the most part, the sun and moon appear the same size in the sky.  At this eclipse, the moon was near its farthest point from earth (apogee).  So it appeared slightly smaller than the sun.  The result is a “ring eclipse,” with a ring of sunlight shining around the sun at the maximum eclipse.

For photo enthusiasts, the images were made with a 1,000mm focal length lens at f/11 through a solar filter with exposures ranging from 1/250 to 1/1000 of a second on print film.

A solar eclipse provides many unique photographic opportunities.  Above I hold a piece of solar filter so that Tim can photograph the eclipse through it.

The Sun Spotter provided projected images of the sun as can be seen above, when the eclipse was near its maximum.  This device was a big hit with all the participants and provided group observing as the event progressed.

Any small hole acts as a pinhole projector.  Here as the sun shines through the ventilation holes in my straw hat, small eclipses are visible on my shirt.

As the sun approached the horizon, it passed behind power towers that carry electrical lines from the dam.  The location provided unique images of the tower in silhouette behind the sun.

The sun set while it was in eclipse.  The image above shows the profile of the distant horizon, the eclipse and the silhouette of a powerline.

Heading for the Denver airport, we stopped at Mesa Verde where we went to the Cliff Palace overlook and visited Spruce Tree House.

The trip’s final leg was through southern Colorado and along the Front Range.  Above we pause at the overlook west of Wolf Creek Pass.

The result was great company, great weather, great scenic vistas, and an outstanding eclipse — successful on all accounts.

May 2012 Skywatching

Solar Eclipse, December 25, 2000
Photo by Patrick Kuras

 The sun is eclipsed by the moon on May 20.  The eclipse is best seen from the Pacific Ocean, south of Russia.  This eclipse is a ring event (annular eclipse).  When the moon moves between Earth and the sun, it is near its farthest point (apogee) from Earth.  Because of its distance, the moon does not completely cover the sun and a ring of sunlight shines around the moon.  From the Chicago area, we will not see much of the eclipse.  From the United States, the ring phases of the eclipse are best  from California, Nevada, Arizona, and New Mexico.

In the Chicago area the eclipse begins at 7:24 p.m. CDT as the sun approaches sunset.  The image above shows the eclipse at 7:50 p.m. CDT when it is only 2 degrees off the horizon.  Sunset follows at 7:50 p.m.  Never look at the solar eclipse without proper optical filters.  See NASA’s web site about how to observe a solar eclipse.

For observers in the western United States, the video above shows a simulation of what is visible from Page, Arizona.  Sunset occurs before the eclipse ends.  (Have fun with the “music.”)

5/15 — Full Moon
5/12 — Last Quarter
5/20 — New Moon (Solar Eclipse)
5/28 — First Quarter

Mercury is very difficult to see in the morning sky as it rises during bright twilight.  It moves behind the sun (superior conjunction) on May 27.

Venus remains an “Evening Star,” but it is rapidly moving between Earth and the sun.  At the beginning of the month, Venus sets about 5-1/2 hours after sunset.  By month’s end it sets only 70 minutes after the sun.  Each night at the same time, Venus appears lower in the western sky.  Venus is heading toward a transit, when it moves in front of the sun (transit) on June 5.

The moon appears near Venus late in the month. The chart above shows the pair along with the star Elnath on May 22.

Mars is well up in the south at sunset in front of the stars of Leo and its brightest star Regulus.  The moon is nearby twice this month.  On May 1st, the moon is lower left of Mars with Regulus nearby.  Later in the month, Mars moves toward the east compared to Regulus and the moon is to Mars’ lower right.

Jupiter is not visible in May.  It is behind the sun (conjunction) on May 13.  It reappears in the morning sky during June.

 Saturn is in the southeastern sky as the sky darkens.  It appears near the star Spica.  On May 4, the moon is nearby to assist with identification.  The constellation Corvus is nearby.  During the night, the group appears to move westward as our planet rotates.  At midnight the grouping is in the south and close to the southwest horizon around 3 a.m., setting shortly thereafter.

In the solar system view, Earth has passed Mars and Saturn. Venus moving faster will catch and pass Earth in early June. Mars, Saturn and Venus are in the evening sky.  Mercury is always near the sun.  This month it is in the morning sky.  Jupiter is on the far side of the sun (the small dot in the middle of the chart) and not visible.  Click the image to view it larger.

Observing the Sky in July 2011

 
 NASA Photo
This month:
 
There is a partial solar eclipse visible only from the ocean south-east of Africa. It is not visible from anywhere in North America.
 

Moon Phases

New 7/1 & 7/30
First Quarter 7/8
Full 7/15
Last 7/23

July has two new moons.  As infrequent as two full moons in a month, popularly known as a “blue moon,” the two-new-moon month has no official astronomical name.  The “blue moon” designation has no official astronomical name, but somewhat goes along with the “once in a blue moon” phrase.  Additionally, sometimes after volcanic eruptions, ash in the atmosphere gives the moon a bluish cast.  Since these eruptions are infrequent, the blue moon color effect related to these events is also very infrequent.  The second new moon in a month is sometimes called a “black moon” in some circles — though again this event has no official name.

 

Look for the Moon and elusive Mercury after sunset early in the month. This diagram and other B&W Diagrams from Sky Calendar. Used with permission.

 Early in the month, Mercury appears in the western sky during evening twilight.  This planet is difficult to see and it never appears in a dark sky.  As with the clustering of the planets in the morning sky in May, use binoculars to view the planet.  At around 9 p.m. in the Chicago area, locate a viewing spot with a good western horizon.  On Saturday, the moon appears to the lower left of Mercury appearing the West-NorthWest sky.   On Sunday, July 3, the moon appears at about the same altitude as Mercury but farther to the left.
 
Support the Sky Calendar:  Get a monthly calendar depicting daily astronomical events.  Subscribe to the Sky Calendar at any time for $11 per year at Sky Calendar, Abrams Planetarium, Michigan State University, East Lansing, Michigan 48824.
 
  
 
 As the moon approaches First Quarter, it appears near the star Spica and the planet Saturn.  Distinctly yellow, Saturn’s rings can be seen through a small telescope.  Close inspection will reveal shadows of the rings on the planet’s cloud tops and Saturn’s largest moon, Titan, in the same plane of the rings.   The chart above shows the waxing moon, Spica, and Saturn on July 7.
 
July 12, Happy Birthday Neptune!  The Royal Astronomical Society of Canada has declared this date as the anniversary of the discovery of Neptune based on Neptune’s orbit.  The planet was first observed on the night of September 23/24, 1846.  The planet takes nearly 165 earth-years to orbit the sun.  On July 12, the planet completes one solar orbit, and one Neptunian year since its first observation from Earth; that’s 6+ human generations!  So let’s go with RASC’s declaration!  Happy Discovery, Neptune! 
 
July 20, a special date1969 — Apollo 11 moon landing.  1976 — Viking 1 martian landing.
 

On July 24, the moon appears near Jupiter during early morning hours.

 
As the moon moves past its full phase and into its waxing phases, it passes Jupiter on  the mornings of July 23 and July 24.  Look for the moon near the Pleiades on the Morning of July 25.
 
 
 
 As the moon moves toward the new phase, it appears near Mars on the predawn hours of July 27.  A thin crescent moon appears to the upper right of a distinctly red-orange Mars.
 
Report here on what you are seeing in the sky in our comments section.  The section is there for questions so that we can include answers in future postings.
 
Happy Viewing!