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2020: Daylight Saving Time Commentary

sunset over ocean
Sunset over the ocean

In this commentary is a different idea about year-round daylight time, based on astronomical concepts for the mid-northern latitudes. Year-round or not, a different approach may yield better results.

by Jeffrey L. Hunt

From the beginning, here’s the conclusion, there’s no daylight to save during the months with the least daylight. Also note that “DST (Daylight Saving Time) is simply a work-time arrangement,” from a paper from the European Union published at the National Institutes of Health (nih.org).  We change our clocks to have more daylight during the evening hours, when there’s daylight available to shift.  The arrangement would work better if the clocks returned to year-round standard time to allow companies, schools, and families determine their own schedules.

The authors of the above study cite myths around DST, including one that shifting the clock one hour ahead creates an extra hour of daylight. Rather, it moves time one time zone eastward.  The authors conclude, that countries should consider “Obliterating DST (in favor of permanent Standard Time) and reassigning countries and regions to their actual sun-clock based time zones. Under such adjustment, social (local) clock time will match sun clock time and therefore body clock time most closely.”

Companies and other organizations can provide flexible work times or change their shifts if their employees want “longer evenings” at particular times of the year.  The authors advocate for year-round standard time.

Around the equinoxes, the popular press focuses on daylight and nighttime; this is followed by a twice-yearly rant about changing the clocks.  When I consider my notes and articles about the sky, I look farther into daylight and nighttime. I break the latter into twilight and darkness.  Twilight, after sunset or before sunrise, has three phases.  Civil Twilight occurs when the sun is 6° below the horizon. Nautical Twilight occurs when the sky is 12° below the horizon, and Astronomical Twilight occurs at the −18° mark.  When the sun is 18° below the horizon, throughout the night and until it reaches −18° altitude in the east, the sky is as dark as it gets naturally.  Statements like, “Dark as midnight,” “darkest before the dawn,” and other similar metaphors have nothing to do with the reality of darkness of the night, and they are inaccurate statements of nature’s light and dark cycles.  

I break the 24 hour cycle into daylight, twilight, and darkness – the time after evening twilight ends and morning twilight begins. Daylight and darkness are equal during late October and then again during early February.

Recently Steve Chapman penned an article  in the Chicago Tribune about the need to keep daylight time throughout the year.  The main focus was about evening driving versus morning driving. Chapman referenced a study about the subject:  Time Well Spent: An Economic Analysis of Daylight Saving Time Legislation.

The study reviews the history of the topic, an analysis of energy consumption, a discussion of effective drive times, and an analysis of daylight during January.  The final conclusion of the article is to keep daylight time during the colder months to mitigate evening driving difficulties.

 Chapman discounts claims about children safety with, “If morning darkness is perceived to pose a danger to kids in some places, schools could push back their start times an hour.”  Anybody with children in high school activities know their children already arrive home as late as 10 p.m. from practices and performances.  Adding another hour to their arrival time is not acceptable to parents, even when school starts an hour later the next morning.

The issue of daylight is not only with January, but starts earlier. By mid-October, the shortening daytime length is noticeable. I have looked at three analyses. One looks from the time of equal daylight and darkness – the time beginning at the end of evening twilight and ending at the beginning of morning twilight – that occurs during late October and recurs during early February. The winter solstice is the mid-point of the time interval.  The second looks at centering the study on the date of Earth’s perihelion (January 2).  The third considers the time around when the sun is truly in the south, at the meridian, at noon on the clock. Here’s what I found:

For the first analysis, I looked at the length of daylight from about the time of equal day – equal darkness, centering on the winter solstice about 50 days later and ending a few days after the equal daylight – equal darkness day, 50 days later, for a total time interval for 101 days, used for all three reviews.  I used sunrise, sunset, and twilight data from the U.S. Naval Observatory for Chicago, Illinois.

For this purpose, the first day is Halloween (10 hours, 24 minutes of daylight).  On the winter solstice, daylight lasts 9 hours, 8 minutes.  The interval ends on February 10, 2021 (10 hours, 25 minutes).  During that 101 days the average day length is 9 hours, 35 minutes.  Because averages “are affected by the extremes,” the median (middle) value is 9 hours, 33 minutes.  So, there’s no extreme value to affect the average, indicating that the change across the interval is slow and consistent without wild variations.  For 38 days (December 2 – January 9) daylight is less than or equal to 9 hours, 20 minutes.

In the second review, I looked at 101 days centering on the perihelion date (January 2), when Earth is closest to the sun. The average day is 9 hours, 38 minutes, while the median value is 9 hours, 29 minutes.

This might be a surprise that the sun is not precisely south every day when our clocks read noon.  Sometimes the sun reaches the south point before clock noon and sometimes later.  This is from the earth’s non-circular revolution around the sun and the planet’s 23.5° tilt.      

In the third review, the 101 days are centered on the date when the sun is precisely south at noon in Chicago, Illinois (January 14).  The average day is 9 hours, 48 minutes, while the median in 9 hours, 28 minutes.

While the mid-point days span 24 days, the average range difference is only 13 minutes, hardly any time to save.  The longer interval gives a larger indication of the daylight available during the colder months at the mid-latitudes, rather than a single month after the winter solstice.

Again, regardless of the time interval that is studied across many days with short daylight, there is no daylight to save during the cold months, when 8.5 hours of work (including a meal break) and an hour of commuting time, 30 minutes each way, are factored in.  Recall that DST is simply a work-time arrangement.

Health experts have weighed in on changing the clock.  The CDC (cdc.gov) described communication that companies should use with their employees to mitigate time change.  The National Institutes of Health (nih.gov) has a paper that describes health risks of changing the clock twice a year. Cardiac risk is documented to be higher in the spring when the clocks are advanced an hour.  Further, this is elevated for individuals who sleep less than 6 hours each night. The article’s authors further note that cardiac incidents could be related to the colder temperatures of March, when the time change is implemented in the US.  The authors conclude: “The following is an easy strategy: (a) move bedtime 1 hour a few days prior to the spring shift, to limit sleep deprivation effects; and (b) take care in exposing oneself to abrupt changes of temperature in the immediate post-shift days.”

The authors ask, “Could such an easy combination of sleep strategies, scarves, hats, and gloves effectively reduce the Cardiovascular effects of DST?”

Consider this conclusion in that year-round daylight time was in effect only one year, 1974.  Critics of year-round daylight time often cite the deaths of eight children as a reason to turn back the clocks in autumn.  Often public policy is driven by such dramatic events. Even private lives are guided by profound personal events that families might say that “we’re not doing that again.” 

Admittingly, it’s a challenge making the hour jump forward each spring and it has documented health effects. Time change for travel outside the home time zone has its individual consequences.  That does not prevent local or world travel, even knowing the minimal or maximum effects of jet lag.

Certainly, the recommendations of Ronnenberg, Winnebeck, and Klerman – the authors of the first study referenced – are worth considering.  Keeping standard time and allowing organizations to modify their own work calendars gives immediate and local control to those the decision affects.  Further a relook at the time zone dimensions to connect them to regional and local work and social patterns is worth a consideration.  What works in Boston is not necessarily effective in Grand Rapids.  Both are in the same time zone, but nearly an hour apart according to the sun’s travel.  The same for North Platte, Nebraska and Ogallala, Nebraska. They are about 50 miles and a time zone apart.

So, in conclusion: There’s no daylight to save during the cold months.  DST is simply a work-time arrangement.  This issue might be better resolved with a return to year-round standard time, allowing local schools, businesses, and families decide their own summertime and wintertime schedules, with the guidance of the health concerns of the CDC.  In the long-term, a national study of how time zones better fit solar time and personal time would help policy makers decide whether time zone realignment is necessary, rather than considering year-round daylight time.  Let’s just delete the idea of year-round daylight time.  We can have more daylight in the evening through year-round standard time with localities and organizations determining their own schedules.

On November 1, 2020, the clock returns to Standard Time. Let’s keep the clock there.

Recent Articles

Mars

2020, Mars During November

The Red Planet’s retrograde motion ends during mid-November. The planet slowly resumes its eastward direction among the dim stars of Pisces. Bright Mars is visible in the east-southeastern sky after sunset during November.

Moon in the Bull's Horns. October 8, 2020

2020, November 3: Morning Star Venus, Mercury and Moon, Bull’s Horns

Mercury begins to join Morning Star Venus in the eastern sky before sunrise. The moon is in the morning sky in the west. Three evening planets are found after sunset, Mars, Jupiter, and Saturn. Mars is in the east-southeast and the Jupiter – Saturn pair is in the south-southwest after sunset. Four hours after sunset, look for the moon between the bull’s horns.

Crescent Moon, Venus, and Aldebaran, July 17, 2020

2020, November 2: Morning Star Venus, Mercury and Evening Planets

Mercury begins to join Morning Star Venus in the eastern sky before sunrise. The moon is in the morning sky in the west. Three evening planets are found after sunset, Mars, Jupiter, and Saturn. Mars is in the east-southeast and the Jupiter – Saturn pair is in the south-southwest after sunset. Today is a heliocentric conjunction for Jupiter and Saturn.

Summer’s Celestial Scorpion

The Celestial Scorpion glides across the southern sky during summer.

by Jeffrey L. Hunt

Scorpius crawls across the southern sky during July from the mid-northern latitudes.  Look low in the southern sky for rosy Antares, the Scorpion’s heart.  The body, tail and stinger resemble a fishhook or letter “J” as they curve toward the horizon and back up into the sky.

Antares is classified as a supergiant star.  It is very larger than our sun, but it is not as hot as our central star’s 10,000°F surface temperature. 

Unlike the artist’s conception of color and temperature, bluer stars are hotter than redder stars.  Our sun is yellow-white and considered an average star in size and temperature.

The classic pincers of the celestial arachnid are marked by Zubenelgenubi (the southern claw) and Zubeneschamali (the northern claw).  They are part of Libra in today’s division of constellations.

When looking toward this region of the sky, we are generally looking in the direction of the galaxy’s center.  Star clouds, gas clouds, and dusty regions are visible here.  Scan across the southern sky and higher in the sky.  Many fascinating features are here.

On the chart above, the spot labelled M4 is a star cluster to the right (west) of Antares. Through a binocular or small telescope, the cluster looks like a small cotton ball.  In a dark location, the cluster is visible to the unaided eye.

 The catalog of celestial objects was first assembled by Charles Messier, an 18th century French astronomer who cataloged star clusters and gas clouds as he searched for comets.  Today, many amateur astronomers seek out the over 100 objects in Messier’s list. The Astronomical League awards star gazers an award for observing the entire register of interesting celestial objects.

Two additional “M objects, “ M6 and M7, are visible.  This star cluster pair is unlike the globular cluster of M4. They resemble tiny jewels scattered across the dark velvet of the sky.

This region of the sky is best viewed when the moon is in a crescent phase or absent from the sky.

On the next clear, moonless evening, take a look southward for the Celestial Scorpion and is wonders.

2020, July 20: One Morning, Five Planets

Mercury and Venus, July 20, 2020
2020, July 20: Venus and Mercury shines from the eastern sky. Mercury is over 23° to the lower left of the brilliant planet.

The five bright planets – Mercury, Venus, Mars, Saturn, and Jupiter – are strung across the plane of the solar system from the east-northeast horizon to the southwest skyline.  Simultaneously, five planets are visible.

Update:  The planets on July 23, click here.

by Jeffrey L. Hunt

This morning the five bright planets appear as beads on a necklace that is stretched across the morning sky.

Mercury, July 20, 2020
2020, July 20: Without the moon this morning, Mercury shines from low in the east-northeast during morning twilight. It is over 23° to the lower left of brilliant Venus.

Without the moon, Mercury shines low in the east-northeast, to the lower left of brilliant Venus.  Mercury is in the sky for several more mornings until it disappears back into the sun’s glare.  In two mornings it reaches its greatest separation (elongation) from the sun.  It never strays far from the sun’s glare, making it a challenge to view.

Venus in Taurus, July 20, 2020.
2020, July 20: In the east, brilliant Venus shines from among the stars of Taurus, 5.1° to the lower left of the star Aldebaran. The Hyades star cluster and Pleiades star cluster are nearby.

Brilliant Venus is to the upper right of Mercury.  Before later twilight brightened the sky, Venus is visible 5.1° to the lower left of Aldebaran.  This star along with the Hyades star cluster form the face of Taurus the Bull.  The Pleiades star cluster is above the scene.

Mars in Cetus, July 20, 2020
2020, July 20: Mars shines from the stars of Cetus in the southeastern sky during early morning twilight. It is 2.7° to the upper left of 20 Ceti (20 Cet).

Meanwhile, Mars is the lone bright “star” in the southeast among the dim stars of Cetus.  This morning it is 2.7° to the upper left of 20 Ceti (20 Cet on the photo). A binocular is needed to see the starfield.

Mars is marching eastward.  It begins the illusion of retrograde motion in early September as Earth approaches and passes the planet.  Earth is between the sun and Mars on October 13, 2020.  On this date, the sun and planet are in opposite directions from Earth.  Near opposition the outer planets are closest to Earth and brightest in the sky.

Jupiter and Saturn in the southwest, July 20, 2020
2020, July 20: Saturn and brighter Jupiter appear in the southwest among the stars of Sagittarius. Jupiter is 4.0° to the lower right 56 Sagittarii (56 Sgr), while Saturn is 4.3° to the lower right of Sigma Capricorni (σ Cap).

Saturn and Jupiter are farther west in eastern Sagittarius.  The planets are retrograding – moving westward compared to the background stars. With a binocular check the planets’ positions compared to the starry background.  This morning Saturn is 4.3° to the lower right of Sigma Capricorni (σ Cap), while Jupiter is 4.0° to the lower right 56 Sagittarii (56 Sgr).

Jupiter was at opposition last week and Saturn is at opposition today.  Jupiter and Saturn appear to reverse their directions in September.  Then Jupiter inches toward Saturn and passes it on December 21, 2020 for a Great Conjunction.

Continue to look for the five planets for the next several days.

Here’s more about the planets during July.

 

2020, July 17: Spectacular Crescent Moon in Morning Planet Parade

The crescent moon, Venus, Aldebaran and the Pleiades, July 17, 2020.
2020, July 17: The crescent moon is in a group with Venus and Aldebaran as the Pleiades appear above the scene during early morning twilight.

This morning’s crescent moon joins Venus in the eastern sky.  Four planets arch across the morning sky.

by Jeffrey L. Hunt

Venus, the crescent moon, and Aldebaran, July 17, 2020.
2020, July 17: The crescent moon is 3.2° to the left of Venus and the brilliant planet is the same distance to the lower left of Aldebaran.

A thin crescent moon joins brilliant Venus this morning in the eastern sky.  The star Aldebaran, in Taurus the Bull, appears nearby.  The moon is 3.2° from Venus, and the sparkling planet is the same distance from Aldebaran.

Mars in Cetus, July 17, 2020.
2020, July 17: Mars, in the southeast, is 2.9° to the upper right of 20 Ceti (20 Cet).

Higher in the southeast, bright Mars shines from the dim stars of Cetus.  It continues to march eastward compared to the starry background.  This morning it is 2.9° to the upper right of 20 Ceti (20 Cet on the photo).

Earth passes between Mars and the sun on October 13.  This is known as opposition.

Jupiter and Saturn in eastern Sagittarius, july 17, 2020.
2020, July 17: Jupiter is 3.7° to the lower right of 56 Sagittarii (56 Sgr) and 1.6° to the upper left of 50 Sagittarii (50 Sgr). Saturn is 4.1° to the lower right of Sigma Capricorni (σ Cap).

Jupiter and Saturn are in the southwestern sky in front of the stars of eastern Sagittarius.  They are moving westward compared to the stars.  This illusion of backwards motion occurs when Earth passes worlds beyond our planet.

Jupiter is a few days past its opposition. Earth passes between the sun and Saturn on July 20.  Both planets continue to retrograde until September.  When they again resume their eastward motion compared to the stars, Jupiter approaches and passes Saturn in a Great Conjunction on December 21, 2020.

This morning, Jupiter is 3.7° to the lower right of 56 Sagittarii (56 Sgr) and 1.6° to the upper left of 50 Sagittarii (50 Sgr).  Saturn is 4.1° to the lower right of Sigma Capricorni (σ Cap).

Here’s more about the planets during July.

 

2020, June 30: The Classic Scorpion Catches the Moon

The moon and the pincers of the scorpion, June 30, 2020.
2020: June 30: The gibbous moon appears 2.7° above Zubenelgenubi in the early evening sky

by Jeffrey L. Hunt

As the moon moves toward its Full phase, the Classic Scorpion catches the lunar orb in its pincers. This evening the moon is 80% illuminated, as it is 9.8 days past the New phase.

One hour after sunset, the moon is caught in the classic pincers of Scorpius.  It is just above (2.7°) the southern claw – Zugenelgenubi. The name reflects that these stars – now part of Libra – were included with Scorpius.  The northern claw – Zubeneschamali – is above the moon.  Because of the moon’s brightness, it might be necessary to block the moon’s light with your hand to see the pincers or look for the stars with a binocular.

The head and body of the scorpion curves down to the left from the moon’s location.  The heart is red-orange Antares.  At this hour, the tail curls below the horizon and back up to the stinger.

2020-2021: Brilliant Planet Venus as a Morning Star

Venus in Virgo, October 24, 2020
2020, October 24: Brilliant Morning Star Venus shines from the morning sky in front of the stars of Virgo. It is 1.9° above Beta Virginis (β Vir) and 3.4° to the lower right of Nu Virginis (ν Vir).

Brilliant Morning Star Venus shines brightly in the morning sky during 2020 and early 2021.

by Jeffrey L. Hunt

Click here for our semi-technical article about the apparition of Venus during 2020-2021.

Bookmark this page and check back frequently for images and updates.

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Slideshow of Venus images

Articles:

Venus makes a grand entrance into the morning sky after its inferior conjunction on June 3, 2020, at 12:44 p.m. CDT. It races into the morning sky and a week after conjunction it rises at Civil Twilight, 32 minutes before sunrise. After mid-June, Venus gleams from low in the east-northeast sky during mid-twilight. By early July, Venus is at its greatest brightness, rises before the beginning of twilight, and appears higher in the sky as sunrise approaches.

During July, Venus moves through the Hyades, with an Aldebaran conjunction on July 12. Watch the planet move through the star cluster with a binocular, during several mornings leading up to the Venus – Aldebaran conjunction.

On July 19, the lunar crescent and five planets are simultaneously spread across the sky with Jupiter low in the western sky and Mercury low in the eastern sky. Venus, Mars, and Saturn are scattered between them.

During August, Venus leaves Taurus, passes through the club and arm area of Orion and into Gemini. On August 15, see the moon join Venus.

Other highlights of the Venus apparition include a grouping with the Beehive cluster in mid-September that includes the crescent moon on September 14; two mornings in October when Venus is about 0.5° from Regulus; a widely spaced Venus – Spica conjunction during mid-November; and an extremely close conjunction with Beta Scorpii in December. Mercury makes an appearance during November, but the gaps with Venus are very wide. At the end of the apparition, Venus passes Mercury, Saturn, and Jupiter. Although they are near the sun, attempt to view the Venus – Jupiter Epoch (close) Conjunction during the day.

Venus reaches its superior conjunction on March 26, 2021, then slowly moves into the evening sky.

Recent Venus Articles

Venus and Moon, October 13, 2020

2020, November: Brilliant Morning Star Venus and Mercury

Brilliant Venus continues to shine brightly in the morning sky. Venus is “that bright star” in the southeastern sky before sunrise. Venus steps eastward in Virgo as Mercury makes its best morning appearance for the year. The crescent moon joins the bright inner planets on November 12 and November 13.

Venus and Moon, October 13, 2020

2020, November 1: Speedy Mercury, Evening Planets

Speedy Mercury joins Morning Star Venus in the eastern sky before sunrise. The first rock from the sun is entering the morning sky for its best appearance of the year. In the evening, Mars shines in the eastern sky, while in the south-southwest Jupiter edges toward its Great Conjunction with Saturn on December 21, 2020.

Jupiter and Saturn, July 17, 2020

2020, October 26: Morning Star Venus, Evening Moon, Planets

Brilliant Morning Star Venus shines in the eastern sky among the stars of Pisces. Mars is visible earlier in the morning, but is low in the sky when Venus rises. In the evening, Mars shines from the east, while Jupiter and Saturn are in the south-southwest as a prelude to their Great Conjunction on December 21, 2020. The moon appears to the upper right of Mars.

Recent Articles

Venus and the moon, June 29, 2020.

2020, October 25: Morning Star Venus, Evening Moon, Planets

The brilliant Morning Star Venus continues to step through Virgo. It is that “bright star in the eastern sky” before sunrise. This morning Venus is near Beta Virginis. In the evening sky, the gibbous moon is between Mars and Jupiter, and near the star Fomalhaut. Mars is in the east-southeast. Jupiter and Saturn are in the east-southeast.

Astronomy

2020: Daylight Saving Time Commentary

In this commentary is a different idea about year-round daylight time, based on astronomical concepts for the mid-northern latitudes. Year-round or not, a different approach may yield better results.

2020: December 21: The Great Conjunction of Jupiter and Saturn

Jupiter, Saturn, Moon, October 22, 2020
2020, October 22: The nearly first quarter moon, overexposed in the image above, makes a nice triangle with Jupiter and Saturn. The planets are 5.9° apart. The moon is 4.4° to the lower left of Jupiter and 4.2° to the lower right of Saturn.

The Great Conjunction of Jupiter and Saturn occurs on December 21, 2020.  Jupiter passes Saturn in the southwestern evening sky.  This is the closest conjunction of the two planets since 1623.  Jupiter – Saturn conjunctions occur every 19.6 years.

by Jeffrey L. Hunt

On December 21, 2020,  in a close conjunction, Jupiter passes Saturn in the evening sky – known as a Great Conjunction.  Look toward the southwest about one hour after sunset.  The bright “star” is Jupiter.  Dimmer Saturn is immediately to the Giant Planet’s upper right.

Read more about the  planets during October 2020

Once a generation, Jupiter catches and passes Saturn. This is known as a Great Conjunction.  Both planets move slowly around the sun because of their distance from our central star.  A Jupiter year is nearly 12 Earth-years long while Saturn revolves around the sun in nearly 30 years.  A Jupiter-Saturn conjunction is rare enough for observers to take notice of this unique pairing.

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Click through the gallery of Jupiter and Saturn images.
(Bookmark this page to return to see updates in this gallery.)

See our detailed article about the Great Conjunction here(updated May 28, 2020)

Jupiter takes nearly 20 years to move past Saturn, travel around the sun, and pass Saturn again.  When Jupiter passes Saturn on December 21, 2020, they will be very close, only 0.1° apart!  This is the closest conjunction since the Great Conjunction of July 16, 1623!  The next Great Conjunction is October 31, 2040, when the two planets are 1.1° apart.  At the next conjunction the planets are low in the east-southeast before sunrise.

November 2020

As viewed from above the solar system, Jupiter passes Saturn in a heliocentric conjunction on November 2, 2020, 49 days before the great conjunction.  The two planets are in along a line that starts with the sun and connects both planets.  As viewed from Earth on this date, Jupiter and Saturn are 5 ° apart.  (See this article for further explanation.)

December 2020

To follow the planet throughout the year, download the daily notes that are linked at the top (current month) and bottom (cumulative index of notes) of this article.  Here’s what to look for during December 2020.

Look low in the southwest, one hour after sunset.  Bright Jupiter is easy to locate.  Dimmer Saturn is nearby, to Jupiter’s upper left.

The moon appears with Jupiter and Saturn on December 16, 2020
2020, December 16. The moon joins Jupiter and Saturn days before the Great Conjunction of 2020.

On December 16, the crescent moon enters the scene. One hour after sunset, the crescent moon (2.3 days past its New phase, 7% illuminated) joins the planets. It is over 6° up in the southwest, about 5° below Jupiter. The Jupiter – Saturn gap is 0.5°.  This is about the apparent diameter of the moon.  Find a clear horizon toward the southwestern sky to find the scene.

Jupiter - Saturn 2020 Great Conjunction
2020, December 21: The Great Conjunction of 2020. Jupiter appears 0.1° to the lower left of Saturn.

Each night thereafter, Jupiter closes on Saturn, until conjunction evening when they are 0.1° apart.  This is close enough to see them in through at a telescope’s low power. Here is the detailed note for conjunction evening:

  • December 21: Jupiter – Saturn Great Conjunction! One hour after sunset, Jupiter is about 12° up in the southwest, 0.1° to the lower left of Saturn. They are 30° east of the sun. Both fit into the eyepieces of modest telescopic powers. Jupiter’s Galilean Satellites are nicely lined up along the equatorial plane of the planet. Ganymede, Io, and Calisto are east of Jupiter, and Europa is west of the planet. Titan is nicely placed to the northwest of Saturn. After the conjunction, Jupiter moves eastward along the ecliptic, separating from Saturn. Each evening the planetary pair appears lower in the sky.
Telescope view of Jupiter and Saturn, December 21, 2020
Jupiter and Saturn are close enough to appear together through a telescope’s low power eyepiece. Saturn’s rings and Jupiter’s four brightest and largest moons are visible as well.

Through a telescope – with an eyepiece that is in the 50x-60x magnification range – Jupiter and Saturn are visible in the same field.  Saturn’s rings are easy to locate.  Jupiter’s four largest and brightest moons – Io, Europa, Callisto, and Ganymede – are evident as well.  On closer inspection, some of Jupiter’s cloud bands are visible.  Some telescopes invert the view compared to the diagram shown here.  Others flip the image left to right.  So the actual view through a telescope may look differently than what is shown here.

The half-full moon is higher in the south-southeast.  Mars is to the left of the moon, over halfway up in the sky in the southeast.  Four bright solar system objects are in the sky – moon, Jupiter, Mars, and Saturn.

Angular Sizes

Moon image by NASA

When viewing the sky, the actual sizes of objects are difficult to determine because there is no depth perception.  We measure objects by their apparent angular size.  Apparent is how large they seem to our eyes.  Angular size is measured in degrees, like the way a protractor measures angles.  The moon appears to be about 1/2° in diameter.  At the Great Conjunction, Jupiter and Saturn are 0.1° apart.  This seems to be close, but they are easily distinguished from each other.  The image above shows the angular size of the moon and 0.1° of angular size on the moon.  The large circular feature is the largest lunar feature, the Imbrium Basin, easily visible without a binocular or telescope.  So the planets are close together, but they do not appear as a “single star” at the conjunction.

Detailed Motion of Jupiter and Saturn

The image at the top of this article shows recent views of the two planets  Notice the separation of the two planets.  At the 2020 Great Conjunction, Jupiter and Saturn are closer than the Venus- Jupiter conjunction of  August 27, 2016 conjunction.

Jupiter and Saturn, their apparent motion in the sky 2020
2020: The apparent motions of Jupiter and Saturn compared to the background stars.

In 1961, the Jupiter – Saturn conjunction occurred in the morning sky, about 2° below 56 Sagittarii. (Note the star’s location on the accompanying chart, nearly 5° west of the Capricornus – Sagittarius border.) The 2020 conjunction occurs about 6° farther eastward, just east of the constellations’ border.

The chart above shows the motions of the planets against the background stars.  Two apparent motions occur to the Bright Outer Planets – Mars, Jupiter, and Saturn.  As Jupiter and Saturn emerge from their solar conjunctions, early in 2020, they appear higher in the sky when weekly observations are made.  They somewhat match the annual westward march of the stars.  This is caused by the earth’s revolution around the sun.  The stars are a calendar.  Over several human lifetimes, the same star is in the same position at the same time and same date each year.

The second motion is a combination of the planets’ slow orbit around the sun, especially for Jupiter and Saturn, since they don’t appear to move far during a year and Earth.  Jupiter and Saturn appear to move eastward (direct motion) compared to the starry background.  During the next year they are among a faint starfield in eastern Sagittarius and western Capricornus.  As our planet catches up and passes between them and the sun (opposition), they appear to move westward (retrograde motion) compared to the stars — retrograde motion.  After Earth passes them, Jupiter and Saturn seem to resume their direct motion compared to the background that moves farther west and rise earlier as the seasons progress.

Jupiter finally catches Saturn in late December for this Great Conjunction. On the chart, notice that Mars passes Jupiter and Saturn during late March 2020.

Read about the 1623 Jupiter – Saturn Great Conjunction here.

Monthly Summaries of What to Watch

(Bookmark this page to return for monthly updates of the planets’ locations.)

Recent Jupiter and Saturn Articles

The crescent moon before sunrise, July 19, 2020.

2020, October 23: Last Call for Venus and Mars in Morning Sky

Mars and Morning Star Venus are nearing their opposition so that they do not appear together in the morning sky for the remainder of 2020. In the evening sky, three planets – Mars, Jupiter, and Saturn – along with the moon, are easy to locate.

Venus and Moon, October 13, 2020

2020, October 21: Morning Star Venus, Evening Crescent Moon

Morning Star Venus and Mars are approaching the date when they do not appear in the morning sky again for the remainder of the year. The lunar crescent appears among the stars of Sagittarius, near giant planets Jupiter and Saturn as they approach their Great Conjunction on December 21, 2020.

Recent Articles

Jupiter and Saturn in Sagittarius, October 4, 2020.
2020 October 4: Bright Jupiter is 7.1° to Saturn’s lower right. In the starfield, Saturn is 1.7° to the lower left of 56 Sagittarii (56 Sgr), while Jupiter is 2.6° to the lower left of Pi Sagittarii (π Sgr) and 2.1° to the lower right of 50 Sagittarii (50 Sgr).

2020, October 20: Morning Star Venus, Evening Lunar Crescent

Brilliant Morning Star Venus shines from the east-southeast before sunrise. It is in front of the stars of Leo. In the evening, the lunar crescent is in the southwest, not far from Jupiter and Saturn that are approaching their Great Conjunction on December 21, 2020. Bright Mars shines from the evening’s eastern sky.

Moon in Taurus, October 7, 2020
2020: October 7: Venus is 5.2° to the lower left of Regulus and 1.3° above Rho Leonis (ρ Leo on the photo).

2020, October 19: Arcturus Helical Rising, 4 Planets

Arcturus returns to the morning sky – its helical rising. Morning Star Venus and Mars are visible before sunrise. Evening planets Mars, Jupiter and Saturn are visible after sunset.

The crescent moon, September 15, 2020
2020, September 15: The moon is in the east before sunrise. The thin crescent moon is 6% illuminated.

2020, October 18: Crescent Moon in West

The crescent moon is low in the west about 30 minutes after sunset near the star Antares. Four bright planets – Venus, Mars, Jupiter, and Saturn – are visible during the night.