Update:  January 20, Lunar Eclipse Photo

On January 20, observers across North America see a total lunar eclipse.  Unlike a total solar eclipse that is only visible for a few minutes from a narrow strip of ground, a lunar eclipse is visible everywhere the moon is above the horizon.  That’s from half the planet.  Another difference is that the light of a lunar eclipse is safe to view.

A lunar eclipse occurs when the moon is near its full phase and it moves through our planet’s shadow.  The entire eclipse occurs over several hours.  The best part of this eclipse occurs for about an hour.  So if there’s cloudy weather, the eclipsed moon might be visible through a break in the clouds.

Our planet’s shadow is composed of a dark inner core where the moon is totally eclipsed.  This is called the umbra. Ringing the umbra is a shadow where sunlight still somewhat shines.  When the moon is in this penumbra, the moon dims only slightly.  Without special equipment to measure the moon’s brightness, most of us will not likely see much change.

The eclipse begins on the evening of January 20 and concludes early the next morning.  Here are the events of the eclipse as seen from Chicago:

• Jan. 20, 8:35 p.m. CST:  The nearly full moon begins to move into the penumbra.  The lunar sphere is about halfway up in the eastern sky.  There’s not much change when the moon is in this part of the shadow.
• 9:33 p.m.: The moon continues to climb into the eastern sky.  The moon begins to move into the umbra.  During the next several minutes, the lower left portion of the moon begins to darken as the moon moves into the umbra.  This partial eclipse continues for over an hour as the moon moves farther into the shadow.  Interestingly, the moon appears to be moving higher in the sky as the eclipse progresses from Earth’s rotation.  The moon is slowly revolving eastward into our shadow.
• 10:40 p.m. – 11:43 p.m. CST: The moon is high in southeast when totality begins.  It is totally immersed in the earth’s shadow, appearing as the image shows at the top of of this article.  The moon appears a deep ruddy orange color.  Depending on the amount of dust in the atmosphere, the moon could be dimly illuminated, nearly disappearing.  The orange color is from some of the sun’s light streaming through Earth’s thin atmosphere into the shadow.  Without the atmosphere, the moon would be completely dark.  In today’s popular press, this is known as a “blood moon.”  This is the time to see eclipse.  The moon is high in the south when totality ends.
• 11:12 p.m. CST: The moon is midway through the total eclipse.  The moon is near its perigee — closest point to earth.  This distance qualifies it as a “super moon” if the moon where full.  So this eclipse will be known popularly as a “super blood moon” or a “blood super moon.”  This is a total lunar eclipse, an elegant name without the popular descriptions.
• Jan. 21, 12:51 a.m. CST, The moon, high in the south-southwest exits the umbra.  It is partially eclipsed.
• 1:49 a.m. CST, The eclipse is finished with the moon high in the southwest.

The next lunar eclipse visible from mid-America is on July 5, 2020 when the moon only passes through Earth’s penumbra.  Another similar penumbral eclipse occurs on November 30, 2020.  Chicago sees part of a total eclipse on the morning of May 26, 2021, but the moon sets before totality sets in.

A lunar eclipse occurs on the morning of January 31 during the second full moon of the month and the new year.  All the events of the lunar eclipse are visible from Asia, Australia, the Pacific Ocean Basin and western North America.

In the Chicago area, the moon sets in the western sky during the maximum phase.

Here are the events of the eclipse for Chicago area observers:

January 31, 4:51 a.m. CST — The moon is low in the western sky (altitude 23 degrees), just about two hours before it sets.  At this time, the moon enters the outer section of the lunar shadow — the penumbra.  For most observers not much change occurs in the moon’s brightness.

5:28 a.m. CST (Moon’s altitude, 16 degrees) — The moon appears lower in the western sky as the earth is rotating.  Morning twilight begins at this time.

5:48 a.m. CST (Moon’s altitude, 12 degrees) — The moon’s descent toward the horizon continues.  At this time the moon begins to move into the darker umbra and the partial eclipse begins.

6:01 a.m. CST (Moon’s altitude, 10 degrees) — The partial eclipse continues and the sky brightens.  Nautical twilight occurs at this time.  The sky is bright enough to distinguish the horizon — the line the separates the sky from the ground.

6:35 a.m. CST (Moon’s altitude, 4 degrees) — The moon’s descent continues as it is now only about 30 minutes before moonset.  Sometimes the moon and sun seem orange when they rise,  This is from the atmosphere erasing the yellow and blue light from  sunlight — atmospheric extinction. (This can also diminish the brightness of celestial objects.)  The moon appears orange during a lunar eclipse when red and orange light are bent through our atmosphere  While the moon is not in total eclipse, yet, the moon appears orange from the eclipse as well as the atmospheric extinction.  At this time Civil Twilight occurs; the sky is bright.  Street lights begin turning off.  It’s easy to distinguish details in terrestrial features.

6:51 a.m. CST (Moon’s altitude, 2 degrees) — The moon is very low in the western sky.  The moon is now completely inside the earth’s shadow — total eclipse.

7:04 a.m. CST — Sunrise

7:06 a.m. CST — Moonset

While all the stages of the eclipse are not visible from the Chicago area, the events leading up to the total eclipse are easily visible.

The articles that follow provide details about the planets visible without optical assistance (binoculars or telescope):

• Chart and Image Collection
• 2018:  The Morning Sky
• 2018:  The Evening Sky
• 2018, January 7:  Jupiter-Mars Conjunction
• 2018, February 10:  Mars-Antares Conjunction
• 2018, March 18: Venus, Mercury and the Moon
• 2018, April 2:  Saturn-Mars Conjunction
• 2018:  Mercury in the Morning Sky
• 2018:  Mercury in the Evening Sky
• 2018:  Five Planets Visible at Once
• 2018:  Venus the Evening Star
• 2017-2019: Mars Observing Year with a Perihelic Opposition, July 27, 2018
• 2018:  Mars Perihelic Opposition
• 2017-2018:  Jupiter’s Year in the Claws of the Scorpion, A Triple Conjunction
• 2018:  Three Planets at Opposition in 79 days
• 2018:  Saturn with the Teapot

One of my astro associates posted this image in another venue and asked whether we could tell the difference between the two images: “Which is 14% bigger than the other?” This is the difference between the size of a typical full moon and a #supermoon  (source)

On the night of September 27, the moon moves into the Earth’s shadow. Observers across the western hemisphere see a total lunar eclipse with the best part occurring from 9:11 p.m. through 10:23 p.m. No special equipment is necessary the eclipse.

The October 8, 2014 Total Lunar Eclipse.  The third eclipse in the current tetrad of total lunar eclipses.  See the text below.

Every planet and moon casts a two-leveled, round shadow into space. From the darker center of the shadow (umbra), the sun is completely blocked. From the outer shadow (penumbra), the sun is partly blocked. Because the moon shines from reflected sunlight, the moon loses its brightness when in passes into the umbra. Sunlight from the earth’s atmosphere gets bent into the shadow causing the moon to gently glow in a coppery color as in the image at the top of this posting.

Here are the events of the evening  (Times are for the Central Time zone, add or subtract time depending on your location)

Moon rise (Chicago): 6:34 p.m. (CDT) — The moon rises in the eastern sky.
Penumbral Eclipse:  7:11 p.m. (P1) — The moon begins moving into the outer shadow of Earth.  Casual observing will see not much difference between a full moon and this phase of the eclipse.
Partial Eclipse: 8:07 p.m. (U1) — The moon is within the lighter penumbral shadow and begins to move into the darker umbra.
Total Eclipse Begins: 9:11 p.m. (U2) — The moon is within the earth’s shadow and for the next 72 minutes the total eclipse occurs
Mid-Eclipse: 9:47 p.m. (Greatest) — The moon is midway through the shadow and midway through the eclipse.  This could be when the moon is at its darkest.
Total Eclipse Ends: 10:23 p.m. (U3) — The moon begins moving from the dark umbra.
Penumbral Eclipse: 11:27 p.m. (U4) — The moon is back into the penumbral shadow.  As earlier in the evening, not much difference is visible between the full moon and this part of the eclipse.
Eclipse Ends:  12:22 a.m. (September 28)
Moon set (Chicago): 7:16 a.m.

The 2016 Observers Handbook reports that this eclipse is the fourth consecutive total lunar eclipse in a series known as a tetrad.  This series of eclipse is rare.  The last tetrad occurred in 2003-2004.  The next tetrad series of consecutive total lunar eclipses is in 2032-2033.  There will be lunar eclipses during the intervening time, even total eclipses.  The tetrad is a series of four total eclipses with no other type in between.  Eight tetrads occur during the 21st century, according to the article.  Two of the images shown above are from this lunar eclipse tetrad.