Tag: moon

2018, December 26: Morning Star Venus and Jupiter

With a waning gibbous moon high in the southwest, brilliant morning star Venus shines during morning twilight from the southeast.  Jupiter is emerging from its solar conjunction.  Find a clear horizon to see Jupiter.

This morning the Venus-Jupiter gap is nearly 23 degrees.  Venus passes Jupiter on January 22.  The conjunction gap is about 2.4 degrees.  Watch the separation close during the opening days of the new year.

More about Venus and Jupiter


2018, December 24: Morning Star Venus and Jupiter

With a bright waning gibbous moon in the west, Jupiter joins brilliant Morning Star Venus in the southeastern sky.  Venus passes Jupiter in a widely-spaced conjunction on January 22.  Watch Venus close the gap during the next month.

More about Venus and Jupiter

2019, January 20: Chicago’s View of A Lunar Eclipse



Lunar Eclipse (NASA Photo)

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.

2018, December 18: Mars and the Moon

With the planetary dance occurring in the southeastern sky during early morning twilight, Mars is the lone bright planet in the evening sky.  It starts in the south near the end of evening twilight.  During the next several weeks, it climbs higher in the southern sky as it moves among the stars.  Here’s our summary of Mars in 2019 until it reaches its solar conjunction.

The waning gibbous moon, 11.7 days past its new phase and 83% illuminated, brightens the sky high in the east this evening.

More about Venus, Jupiter, and Mercury in the morning sky:

2019, February 18: A Venus-Saturn Conjunction

In early February 2019, Venus continues to dominate the pre-sunrise sky.  Saturn emerges from its solar conjunction in January.  Venus passes 1.1° to the upper left of Saturn on the morning of February 18, less than 4 weeks after its Jupiter conjunction.  Here are the events leading up to the Saturn conjunction:

  • February 1: Saturn (m = 0.6) rises just before the beginning of twilight. At 45 minutes before sunrise, Venus (m = −4.3), 18° up in the southeast, is 18° to the upper right of Saturn, 7° up in the southeast.  Jupiter (m = −1.9) is nearly 10° to the upper right of Venus.  The waning crescent moon (26.5 days old, 10% illuminated) is about midway between Venus and Saturn. ( The magnitude, m, of a star is a numerical value assigned to its brightness.  The brightest stars have a magnitude of 1.  However, the planets and exceptionally bright stars, like Sirius, are brighter.  So in order to rank really bright celestial objects, the magnitudes become negative.  The sun is so bright (m=-26) it makes daytime on our planet!  So looking at the magnitudes here, Venus is brighter than Jupiter; Jupiter is brighter than Saturn.  Even when the moon displays a thin crescent it is brighter than Venus.)

  • February 2: The waning crescent moon (27.5 days old, 5% illuminated) is 3.1° to the lower left of Saturn. The Venus-Saturn gap is 16.7°.
  • The gap continues to close: Feb. 9, 9.3°; Feb. 10, 8.6°; Feb. 11, 7.3°; Feb. 12, 6.1°; Feb. 13, 5.1°; Feb. 14, 4°; Feb. 15, 3.3°; Feb. 16; 2.2°; Feb. 17, 1.5°.  As we look at the moon, it is about 0.5° across.  That’s about equal to the size of your pointer finger when you stretch out your arm.  Two full moon diameters is 1.0°.

  • Feb. 18, Conjunction morning!  The separation is 1.1°. Venus is to the upper left of Saturn.  The planets look close, but they are about 900 million miles apart.  Traveling at the speed of our fastest spacecraft (25,000 miles per hour), the distance between them could be traversed in over 4 years! After the conjunction the gap widens: 19, 1.4°; Feb. 20, 2.4°; Venus is to the left of Saturn.

A second Venus-Saturn conjunction occurs during Saturn’s 2019 apparition.  It occurs in the southwest in mid-December.

Here is our feature article about Venus and its 2018-2019 appearance:

Here is a summary of the next six Venus-Saturn conjunctions:

                                      Venus-Saturn Conjunctions, 2019-2025

Date Location Separation Description
December 10, 2019 Southwest after sunset. 1.8° Look for the pair in the southwest after sunset.    Venus is to the lower left of Saturn.
February 6, 2021 Southeast before sunrise. 0.5° This is a very difficult conjunction to see.  Venus is only 2° up 10 minutes before sunrise.
March 29, 2022 East-southeast before sunrise. 2.1° About an hour before sunrise, the pair is easy to see. Venus is to the upper left of Saturn.  Mars is nearby, 4.4° to the upper right of Saturn.  On the morning before the conjunction, the waning crescent moon joins the scene.
January 22, 2023 West-southwest after sunset. 0.3° The pair is 8° up one hour after sunset.  Venus is left of Saturn.  The waxing crescent moon is about 8° to the upper left of Venus on the evening before the conjunction
March 21, 2024 East before sunrise. 0.6° This is another difficult conjunction to view.  The pair is less than 5° up 10 minutes before sunrise.  Venus is to the upper right of Saturn.
January 20, 2025 Southwest after sunset. 2.2° This is an easily viewed conjunction.  Venus is to the upper left of Saturn.  The pair is over 20° up in the southwest 2 hours after sunset.


2018: Morning Star Venus and Moon During Early December Mornings

Brilliant Morning Star Venus shines in the southeastern sky in early December.  Look for a photogenic grouping of  Venus, Spica, and the Moon early in the month:  Here’s what to look for:

  • December 2: One hour before sunrise, the waning crescent moon is 13° above Spica. The Venus-Spica gap is 6.8°.  Mercury, is 7° up in the southeast, 30 minutes before sunrise.

  • December 3: One hour before sunrise, there is a spectacular grouping of the waning crescent moon Venus, and Spica.  They make a triangle, with the moon at the upper left corner.  The moon is 5° above Venus and 7° to the left of Spica. Venus is 7.4° to the lower left of the star.

  • December 4: One hour before sunrise the waning crescent moon (26.8d, 8%) is 9° to the lower left of Venus.  The Venus-Spica gap is nearly 8°.  The trio (Venus, Moon, and Spica) is nearly in a line.

Our feature article about the morning appearance of Venus: