2017, July 21: Venus and Moon

That brilliant star above the moon this morning is Venus.  The moon is nearly 8 degrees to the lower left of the Morning Star.  They were slight closer yesterday morning.

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2017, June 20: Venus and Moon

Brilliant Venus and the waning crescent moon sparkle in the eastern morning sky this morning.  The two are about 7.5 degrees apart.

Notice the night portion of the moon,  It is gently illuminated by sunlight reflected from planet Earth:  Earthshine!


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2017, June 20: Summer Solstice

Summer Solstice, June 20, 2017, 11:24 p.m. CDT.  This video explains more about the summer solstice:


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2017, June: Saturn at Opposition

The Ringed Wonder reaches opposition on the morning of June 15.  At this time our planet is between Saturn and the sun.  On the evenings around opposition, Saturn rises in the opposite direction from the sunset point.  As Earth rotates, it rises higher in the sky each hour.  At midnight it is in the southern sky.  From that time, the planet begins to appear lower in the sky, setting in the southwest as the sun rises in the northeastern sky.

On the evening of June 8, the waning gibbous (just past full) moon appears nearly 3 degrees to the upper left of Saturn.  The reddish star Antares is nearly 16 degrees to the upper right of Saturn.

This is the last opposition of naked eye planets this year.

The three outer planets, which includes Pluto, have oppositions this year, but they are only observed with optical assistance:

  • Pluto,  July 10
  • Neptune, September 5
  • Uranus, October 19

Observers are interested in oppositions because at this time, the planet at opposition is closest to Earth and so the planet’s observable features are easiest to see through telescopes.  The planet is in the sky all night and highest in the sky at midnight.

Photo credit:  Lowell Observatory

During an 1894 Mars opposition, Percival Lowell first began to document his later disproved discovery of “canals.”  While remote satellites give close-up images of the distant worlds, there are few more memorable events than seeing Jupiter, Saturn or Mars through a telescope.

In 2018, the three naked eye outer planets appear at opposition within an 80-day period:

  • Jupiter, May 8
  • Saturn, June 27
  • Mars, July 27

As they emerge from their solar conjunctions later in the year, they appear with Venus in the morning sky, including another Venus-Jupiter Epoch Conjunction.  More about these events as they approach.

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2017, June: Jupiter in Evening Sky

Jupiter is the bright “star” in the southern sky during the early evening hours this month. On June 3, the waning gibbous moon appears about 2 degrees to the upper left of the giant planet.  Spica appears 11 degrees to the lower left of Jupiter.  The constellation Corvus the Crow is nearby.

Jupiter ends its retrograde motion on June 8th and begins to move eastward again as compared to the sidereal background.  It slowly appears to move toward Spica, passing on September 5.

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2017, June: Venus in the Morning Sky


Venus is the “bright star” in the eastern predawn sky during June 2017.

On June 3, Venus reaches its greatest angular separation from the sun, rising about 2 hours before sunrise.  During its appearance so far, Venus has been rising during morning twilight.  On June 10, this bright planet begins rising before morning twilight starts.  By month’s end, it rises over 2 hours, 30 minutes before the sun and over twenty minutes before the beginning of morning twilight.

On the mornings of  June 20 and June 21, the waning crescent moon appears near Venus.  On June 20, the moon is nearly 7.5 degrees to the upper right of Venus.  On the next morning our lunar neighbor is about the same angular distance to the lower left of Venus.


Update:  Here’s the view this morning, June 20.


Update 2:  Here’s the view this morning, June 21.

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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.