2021, May 26: Lunar Eclipse, Morning Worlds

May 26, 2021:  This morning a lunar eclipse occurs.  Your view of event depends on your location.  Better views are farther west in the US and Canada.  Australia, New Zealand, and the Pacific Ocean experience the entire eclipse.  Bright morning planets Jupiter and Saturn are in the southeastern sky.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 5:21 a.m. CDT; Sunset, 8:15 p.m. CDT.  Check local sources for sunrise and sunset times for your location.

Morning Sky

A lunar eclipse occurs this morning, although the moon sets before the complete cycle of the eclipse occurs for most of the Americas. In the detailed notes, this is summarized as a disappointing miss for most of the Americas.

For the eastern US, the moon is low in the western sky during the eclipse’s early stages, setting before the best part of the eclipse begins.  From the western US, the total eclipse phase is visible, but the lunar orb is low in the sky.  The scene is picturesque with mountains, cacti, or cities on the horizon near the moon, but not the best location in the sky for eclipse observing.  Additionally, twilight begins during the eclipse so the sky is brightening while the moon is dimming.

In the description below, Hawaii has a nice view of the entire eclipse while the moon is higher in the sky and it ends before morning twilight commences.

A lunar eclipse occurs when the moon moves through Earth’s shadow.  Nighttime is from Earth’s shadow, although the shade is projected into space.

A shadow of a nearly spherical object is circular with two regions.  An outer circle is still somewhat illuminated, but slightly darker.  This is known as the penumbra.  The inner shadow, umbra, is dark. 

When the moon enters the penumbra, not much darkening is noticed without an apparatus to measure the change in the moon’s reflected sunlight.

The umbra is not completely dark.  Red and orange sunlight stream through the earth’s atmosphere, that filters out the bluer colors, and gently illuminates the moon when it is here.

From the chart above, the moon can move along a multitude of paths through the shadow.  It can only move through the penumbra – a penumbral eclipse.  The lunar sphere can move in such a way that only part of the moon moves into the umbra, a partial eclipse.  When the moon is completely immersed in the umbra, that is a total lunar eclipse.  That is what occurs this morning, in places where the moon is in the sky.

The lunar eclipse occurs for observers where the moon is above the horizon, for half the earth’s surface.  The moon’s track through the shadow is at the same time for everybody observing, only distinguished by the time zone designations, as demonstrated in the local descriptions that are below.  Locations farther west see the moon higher in the sky and for a longer period during the eclipse.

Looking at the historical records , some observers report that the moon disappeared during a lunar eclipse, although this was before telescopes were used to look at the sky.

The moon moving from right to left (west to east) as it orbits Earth, first moves into the penumbra, although Earth’s rotation is faster and the moon appears farther west in sky.  At the next stage the edge of the moon, known as the limb, moves into the umbra and a partial phase begins.  When the entire moon moves into the umbra, the total phase begins where the red-orange colors are vividly displayed.

The darkness or redness of the eclipse is difficult to predict and it is affected by the amount of dust in the atmosphere that blocks the bluer colors and potentially even the red and orange light, making the moon disappear completely.

Depending on the geographic location, as the moon darkens, stars become visible that are normally washed away by the bright light from the full moon.

This eclipse when the moon is at perigee, closest to Earth.  This full moon is the Flower moon.  The total phases of the eclipse are sometimes very red-orange, and the term “blood moon” is added to the description.

Whatever the media calls this event, it is a perigee lunar eclipse.

Here are notes for specific American cities:

Boston:  The moon sets 36 minutes after the moon enters the penumbra.

Chicago:  Morning twilight begins at 3:18 p.m. CDT. The moon enters the penumbra at 3:47 a.m. when the moon is less than 14° up in the southwest. The sky is brightening with mid-twilight at 4:19 a.m. CDT.  The partial eclipse begins at 4:44 a.m. when the moon is less than 6° up in the sky.  Sunrise is at 5:21 a.m. CDT. The moon sets at 5:27 a.m. CDT.

Albuquerque:  The penumbral phases of the eclipse begin at 2:47 a.m. MDT.  The moon is less than 30° up in the south-southwest. Morning twilight starts about 20 minutes before the total eclipse begins.  The total phase begins at 5:11 a.m. MDT and finishes 14 minutes later when the moon is only 5° up in the west-southwest. This occurs after mid-twilight when the sky is brightening.  The moon sets at 6:03 a.m. MDT.

Sacramento:  The penumbral eclipse begins at 1:47 a.m. PDT, when the moon is 30° up in the sky.  The partial phases begin about an hour later, 2:44 a.m. PDT. Morning twilight begins at 3:54 a.m. PDT. The total eclipse begins at 4:11 a.m. PDT and leaves at 4:25 a.m. PDT, when the moon is about 13° above the west-southwest horizon. Mid-twilight occurs at 4:50 a.m. PDT. The moon sets at 5:46 a.m. PDT as the moon moves out of the umbra, displaying its partial phases.

Honolulu:  The city and state experience the entire eclipse.  Penumbral begins, May 25, 10:47 p.m. HST when the moon is less than halfway up in the south-southeast.  The partial eclipse begins when the moon is over halfway up in the sky at 11:44 p.m. HST (May 25).  The total eclipse begins at 1:11 a.m. HST (May 26), ending 14 minutes later when the moon is over halfway up in the south-southwest.  Partial phases end at 2:52 a.m. HST, and the eclipse ends completely at 3:49 a.m. HST when the moon is about 25° up in the southwest.  The eclipse is finished long before morning twilight begins at 4:29 a.m.

For the morning planets, Jupiter and Saturn are low in the southeastern sky before sunrise.

Articles and Summaries.

• Venus as an Evening Star
• Venus Evening Star (Summary)
• Mercury during May 2021
• Mars during 2021 (Summary)
• Mars during May 2021
• Planets during May 2021

Detailed Note: A total lunar eclipse occurs this morning, although North America and South America do not see the total eclipse cycle that is visible from the Pacific Ocean, Australia and New Zealand.  From the Chicago area and nearby locations, this is a disappointing miss. The eclipse begins at 3:47 a.m. CDT when the lunar orb enters Earth’s penumbra.  Most observers do not see much darkening when the moon is in the outer ring of the terrestrial shadow. By the time the moon begins to enter the darker umbra, the lunar orb is only 6° up in the southwest. By moonset at 5:27 a.m. CDT, the moon is partially eclipsed, although the sun appears above the horizon at 5:21 a.m. CDT.  The official Full phase (Flower moon) occurs during the eclipse, 6:14 a.m. CDT, after moonset in Chicago. Farther west in the US, more of the eclipse is visible.  From Sacramento, CA, the moon reaches its greatest eclipse at 4:18 a.m. PDT, when the lunar orb is 14° up in the southwest.  The moon begins to exit the umbra only 11 minutes later. At this location, by the time the moon leaves the darker umbra it is near the west-southwest horizon. The moon sets before the moon fully leaves the umbra. Depending on your location during the darker stages of the eclipse, the Milky Way may be visible and certainly dimmer stars in Scorpius region are visible.  Jupiter and Saturn are in the southeastern sky.  The dimmer stars nearby should be near their normal visibility when the moon is not present.  Jupiter is over 26° up in the southeast, while Saturn is about 18° to the Jovian Giant’s upper right. Saturn is retrograding in Capricornus, to the right of θ Cap.  It reversed its direction less than a week ago.  Aldebaran sets with the sun.  Its setting time is one minute different from sunset.  The planet trio – Venus, Mercury, and Mars – continues its display in the western sky after sunset.  Mercury is nearing the conclusion of its best evening appearance of the year. Begin looking 30 minutes after sunset.  Venus is nearly 8° up in the west-northwest.  Use a binocular to spot Mercury (m = 1.8), 2.3° to the upper left of the brilliant planet.  Fifteen minutes later, Venus is over 5° in altitude and Mercury is over 7° above the west-northwest horizon.  Mars is nearly 27° up in the west.  By one hour after sunset, Venus is about 3° in altitude and Mercury is nearly 5° up.  Mars is in Gemini, 2.3° above δ Gem and 6.1° to the lower left of Pollux.  Two hours after sunset (10:15 p.m. CDT), the moon (15.3d, 100%) is 10° up in the southeast, 7.0° to the lower left of Antares (α Sco, m =1.0).