Jeffrey L. Hunt is an educational technologist living in suburban Chicago. When he's not learning about and implementing technology in classes, he's running or looking at the stars.
2020, November 2: Jupiter passes Saturn in a heliocentric conjunction, as viewed from outside the solar system.
As the Great Conjunction of Jupiter and Saturn nears, Jupiter passes Saturn if viewed from the sun.
by Jeffrey L. Hunt
As Jupiter edges closer to Saturn in the evening sky of Earth, Jupiter passes Saturn as viewed from outside the solar system on November 2, 2020. This is known as a heliocentric conjunction. The next one for these two planets is on December 7, 2040.
If we were on Jupiter on November 2, we would say that Saturn is at opposition. Saturn is in the opposite direction in the sky from the sun. If we were Saturnians, then we would say that Jupiter is at inferior conjunction, between Saturn and the sun. Notice on the chart above that Earth is not close to the line of the heliocentric conjunction.
From these two planets in alignment, a question may develop about more planets appearing in a line from the sun. Astronomer Jean Meeus (Mathematical Astronomy Morsels, pp. 186-191) addresses the question. Without reciting his reasons, the answer: “Never!” The dynamics of fast – moving Mercury to slow-moving Pluto (Yes, Pluto is one of the “Classic Nine” planets.), there is never a moment when all nine are in a line stretching from the sun. He further notes that it’s impossible for even three to be in a line. Reasonably they can be within a 60° angle of each other, 50° if Pluto is not included.
2020, November 2: Jupiter is 5.0° to the lower right of Saturn, about one hour after sunset. Look toward the south-southwest.
In our sky, the planets are 5.0° apart. They can be found in the south-southwest about an hour after sunset on November 2. Saturn is to the upper left of bright Jupiter. The planets are in front of the stars of eastern Sagittarius. The famous “Teapot” shape is to the lower right of the planets.
During October 2020, Mars appears as a very bright star in the eastern evening sky and western morning sky. Mars is closest to Earth on October 6, and at opposition a week later. The moon passes the planet twice, October 3 and October 29.
2020: Halloween Full moon first since 1955 in Central Time Zone and since 1944 for North America. Photo Credit (https://www.publicdomainpictures.net/)
A rare Halloween Full Moon, 76 years in the making, is visible across most of the planet in 2020.
by Jeffrey L. Hunt
No, it’s not Comet Halley, but it’s been 76 years in the making, a Halloween Full Moon that is visible nearly across the entire globe.
During Halloween in 1944, a Full Moon occurred for nearly all the globe. This was the last time a Halloween Full Moon was globally visible.
Many images of the season display cats with curved backs, leafless trees, ghosts, goblins, ravens, bats, and full moons (such as those on the accompanying graphic), but a Halloween Full Moon is a rare occurrence.
As the moon revolves through space, we view its sunlit surface in various shapes — the moon’s phases. We give them interesting names such as waxing gibbous or waning crescent.
Observers from half the globe can see the moon simultaneously. As Earth rotates and the moon rises higher into the sky. As it sets in one part of the globe, the moon rises in another part of the world.
No special equipment is needed to view this Full Moon. It is no different from any other full phase, except for the sentimentality of the date.
Because October has 31 days and a lunar cycle occurs every 29.5 days, a Halloween Full Moon means that the month’s first full moon occurs on October 1 or 2, depending on the time of the full phase. It also marks the year’s Harvest Moon (October 1, 2020).
Because of the varied uses of the term “blue moon,” the Halloween Full Moon is the second of the month, and might be named a “Blue Halloween Full Moon.”
Many casual observers that see a bright moon might think that it’s full. The moon might be gibbous or nearly full. Astronomically, the moon is full for an instant of time when it is opposite the sun from Earth. During that night when the moon appears as a complete globe of light, we frequently use the “full moon” term. Even a day before or after the actual date, the term is used.
For a reasonable discussion, let’s dig into the astronomical definition. Further it is important to consider the observer’s location and time system (standard or daylight) that is used there. Every place on Earth does not have the same clock time or even display the same date. For example, during daylight time 1 p.m. in New York is 2 a.m. the next calendar day in Tokyo. Because of the use of time zones, the fact that the earth is round, and not all places have daytime and nighttime simultaneously, tells us to make this distinction. A full moon may not occur on the same day for all earthly locations. To determine whether a Halloween Full Moon occurs, the local calendar must read October 31 and the full moon time must be from 12:00:01 a.m. to 11:59:59 p.m. local time.
Surveying U.S. Naval Observatory data from 1930 to 2050, the window occurs nearly every 19 years. Here are the Halloween Full Moons. Here is when recent Halloween Full Moons occurred:
1944, October 31, 7:35 a.m. CST. This was before Daylight Saving Time was used. The entire planet had a Halloween Full Moon
1955, October 31, 12:04 a.m. CST. There was no Halloween Full Moon for western North America and the Western Pacific to the International Date Line. All locations eastward to to the International Date Line had the Halloween Full Moon.
2020, October 31, 9:49 a.m. CDT. All locations eastward to GMT+8 time zone with daylight time or GMT+9 hours with out daylight time.
2039, October 31 (5:36 p.m. CST). With the current public dislike for daylight time, the future of it is unpredictable. Standard time is used in this note.
In the Western Hemisphere, the year 2001 was a near miss for a Halloween Full Moon for North and South American time zones east of Mountain Time, and was the consequence of daylight time. It occurred November 1 (12:41 a.m. CDT). One cycle earlier, in 1982, the potential Halloween Full moon occurred nearly eight hours too late (November 1, 7:57 a.m. CDT) for North America and South America. In 1974, another near miss occurred when the full moon occurred at 8:19 p.m. CDT on October 30.
The 2020 Halloween Full Moon is visible in North America and South America, and most of the globe, except for regions west of the International Date Line, such as Eastern and Central Australia, New Zealand, Papua New Guinea, Guam, and eastern Russia. The Halloween Full Moon occurs in all time zones eastward from the Prime Meridian through Europe, Africa, Asia, India, Indonesia, Korea, and Japan to western Australia. It occurs eastward to GMT+8 hours, with daylight time and GMT+9 hours for countires without daylight time. For regions to the east of these time zones, the Full Moon occurs there during the early morning hours of November 1.
The next Halloween Full moon is during 2039 in North America and South America. Depending on the regional status of the use of daylight time, possibly two time zones east of the Greenwich, England meridian can witness a Halloween Full Moon. It’ll occur before Comet Halley’s return in 2061. So “celebrate” this year’s Halloween Full Moon!
2020, September 14: Ninety minutes before sunrise, look for the moon and Venus near the Beehive star cluster. The moon is 5.0° to the lower left of Venus.
The crescent moon and Morning Star Venus pass close to the Beehive star cluster.
by Jeffrey L. Hunt
Moving among the dim stars of Cancer, brilliant Morning Star Venus passes the Beehive star cluster during mid-September.
2020, September 14: Through a hazy sky, the moon is 5.0° to the lower left of Venus.
Venus has appeared in the morning sky since mid-June, and it is there into the new year. It continues to step eastward compared to the starry background in its morning sojourn.
The planet continues to rise over 3.5 hours before sunrise. By the beginning of morning twilight that starts about 100 minutes before sunrise, Venus sparkles above the skyline in the eastern sky. Like the other easily visible planets, Venus appears as an overly bright star, the brightest “star” in the sky. It even outshines Sirius, nighttime’s brightest star.
2020, September 14: The moon is 5.0° to the lower left of Venus.
All the planets appear to move along the ecliptic, an imaginary line that is the plane of the solar system. The ecliptic makes a great circle around the sky through the familiar zodiacal constellations. Mars, shining in the southern sky during morning twilight, is among the stars of Pisces, while evening planets Jupiter and Saturn are in eastern Sagittarius.
Cancer is a dim constellation between the Gemini Twins and Leo, where Venus moves at month’s end.
The Beehive star cluster is a distant clump of stars that are similar to the famous Pleiades (Seven Sisters), but they are farther away, appearing dimmer to our eyes. The cluster is also known as the Praesepe (Manger).
The Beehive star cluster looks like a fuzzy cloud to the unaided eye. Its best view is through a binocular, as it spills outside a telescope’s eyepiece.
The cluster is a phase of the life of a star where astronomical theory predicts that stars are formed in bunches. This cluster has about 200 stars; about a dozen appear through a binocular.
On the morning of September 14, look about 90 minutes before sunrise for brilliant Venus and the lunar crescent that is 12% illuminated. They are 5.0° apart. The star cluster is 2.7° to the upper left of Venus; that’s about half the Venus – Moon gap. The lunar crescent is 4.6° to the lower left of the cluster. The star Delta Cancri (δ Cnc on the chart above) is 0.9° to the upper left of Venus.
Venus is slightly closer to the Beehive on the morning of September 13 and the moon is above the scene. See the detailed notes below for more specific directions.
Photographers can catch the scene with a camera that has time exposure settings and a tripod mount or another means of holding a steady camera. Exposures from 1 to 5 seconds yield satisfactory results. Exposures that are longer reveal Earthshine on the moon, sunlight reflected from Earth’s clouds, continents, and oceans that gently illuminate the nighttime moonscape.
The detailed notes that follow provide more specifics:
September 13: Venus passes 2.3° to the lower right of the Beehive cluster. The planet is also 1.5° to the upper right of (Delta Cancri (δ Cnc). One hour before sunrise, find the brilliant planet about 28° up in the east. The waning crescent moon (25.3 days past the New Moon phase, 20% illuminated) is over 10° above Venus. The moon is also 6.1° to the lower right of Pollux.
September 14: Venus is 5.0° to the right of the crescent moon (26.3d, 12%) and 0.9° to the lower right of δ Cnc. With a binocular observe that the Beehive cluster is 2.7° to the upper left of Venus and 4.6° to the upper right of the lunar crescent. One hour before sunrise, find Venus about 28° up in the east.
2020, September 15: The crescent moon and Venus in the morning sky.
September 15: One hour before sunrise, Venus is nearly 28° up in the east. It is 1.4° to the lower right of δ Cnc and 3.3° to the lower right of M44. All three of these objects are nearly along a line that starts with the star cluster and ends with Venus. The moon (27.2d, 6%) is about 15° up in the east. It is 5.4° to the upper left of Regulus
2020, September 15: The moon is in the east before sunrise. The thin crescent moon is 6% illuminated.
Here is a daily summary about the planets during September.
After the sky cleared today, the International Space Station made a bright pass across the mid-northern latitude states this evening near Jupiter and Saturn in the sky. The ISS was brighter than the planet Jupiter.
2020, September 5: Morning Star Venus appears during twilight with Sirius, Procyon, Orion, and Gemini.
The bright stars of September’s morning shine from the east before sunrise.
by Jeffrey L. Hunt
Venus and Sirius shine from a spectacularly clear sky this morning during twilight. Venus is making its way through the dim stars of Cancer. It is to the lower right of the Gemini Twins – Castor and Pollux.
Sirius, the brightest nighttime star, is beneath Orion and its bright stars Betelgeuse and Rigel.
Three stars – Betelgeuse, Procyon, and Sirius – make the Winter Triangle. These stars are prominent in the evening sky during the winter months in the northern hemisphere.
2020, September 6: Mars and Moon. (Composite image)
Update for Mars and Moon, September 5/6.See more here.
2020, September 5: Mars is 9.6° to the upper left of the lunar orb. Among the stars of Pisces, the Red Planet is 2.2° to the upper left of Nu Piscium (ν Psc) and 2.6° to the lower left of Omicron Piscium (ο Psc).
The bright gibbous moon appears near the Mars this morning as a prelude to tonight’s celestial encounter.
by Jeffrey L. Hunt
The bright gibbous moon – overexposed in the image above – that is over 90% illuminated this morning appears near the planet Mars.
This evening the moon appears close to the Red Planet as they rise into the sky around 10:30 p.m.
They appear together throughout the night as the lunar orb slowly moves away from Mars.
2020, September 5: Venus – among Cancer’s dim stars – is 9.9° to the lower right of Pollux.
Farther east, Venus sparkles among the dim stars of Cancer. The Gemini Twins – Castor and Pollux – are to the upper left of Earth’s Twin Planet.
Here is a daily summary about the planets during September.
2020, September 4: Venus, Sirius, Procyon, and Orion shine from the eastern sky during early morning twilight.
Morning Star Venus and Sirius shine from the eastern sky during morning twilight during September.
by Jeffrey L. Hunt
Brilliant Venus shines from the eastern sky during early morning twilight. The planet gleams in our sky from reflected sunlight. This morning the planet is nearly 82 million miles away.
Sometimes Venus is called the “Earth’s Twin” planet because the two planets are similar in size. Venus is completely veiled in clouds that are highly reflective. They return to space nearly 70% of the sunlight that falls on them. The clouds, oceans, and continents of Earth reflect about 40% of the sunlight that reaches them.
Sirius is visible low in the east-southeast during morning twilight. Sirius, the brightest star in Canis Major (Great Dog), is 8.6 light years away. The star is over 20 times brighter than our sun.
For the next several weeks, the brightest star and the brightest planet shine in the morning sky.
While brighter than our central star, Betelgeuse and Rigel in Orion to the upper right of Sirius, are considerably farther away.
Betelgeuse shines with the energy of over 13,000 suns.
Betelgeuse is a red supergiant – meaning that it is unusually large and intrinsically bright. At a distance of about 500 light years, this enormous red star would cover several planets’ orbits if it were in our solar system.
Rigel, a topaz blaze in the morning sky, is even brighter. It shines with the power of over 40,000 suns.
The spacing of Betelgeuse, Sirius, and Procyon in the sky make the Winter Triangle. This trio is prominently placed in the sky during the evenings of the winter months.
Sirius, a few weeks past its first morning appearance, now shines with other bright stars in the morning. Step outside and look the next clear morning for the brightest planet and the brightest star.
Here is a daily summary about the planets during September.
2020, September 4: Mars is 2.1° to the upper left of Nu Piscium (ν Psc) and 2.6° to the lower left of Omicron Piscium (ο Psc).
Morning Star Venus, bright Mars, and the constellation Orion shine from the skies this morning.
by Jeffrey L. Hunt
With the bright moon in the sky, outside the frame of the image, Mars shines brightly from the dim stars of Pisces. The planet is slowly stepping eastward in the constellation, to the left in the photo.
Tomorrow evening (September 5) and the following morning, the bright moon appears near Mars
On September 9, the planet seems to reverse its direction and begins to move westward compared to the stars. This retrograde motion is an illusion as our faster moving planet approaches the Red Planet.
Mars Begins Retrograde: During September, Mars begins its retrograde motion east of Nu Piscium (ν Psc). It reverses its direction and ends the month near Mu Piscium (μ Psc).
The chart above shows the motion of Mars compared to the stars during September.
Earth and Mars are closest on October 6. Earth passes between the sun and Mars on October 13. During the next month the planet continues to grow in brightness and apparent size through a telescope, although unlike what is shown in the social media memes.
2020, September 4: Venus moves into Cancer to the lower right of Castor and Pollux, the Gemini Twins.
Farther east, brilliant Morning Star Venus shines brightly from below Castor and Pollux, the Gemini Twins. This morning it moves into the dimmer stars of Cancer. In 10 days, the crescent moon joins Venus as it moves near the Beehive star cluster.
2020, September 4: Orion, with its bright stars Betelgeuse and Rigel, rise into the late-summer morning sky.
Orion rises in the southeast this morning. Its bright stars, Betelgeuse and Rigel, mark opposite corners of the famous star pattern. In the clear skies this morning, the Orion Nebula (M42 on the photo) stands out. (The short time exposure reveals some color that is not visible, even with a binocular.)
Here is a daily summary about the planets during September.
The Harvest Moon is the full moon that occurs nearest to the autumnal equinox in the northern hemisphere.
by Jeffrey L. Hunt
The Harvest Moon is the moon that occurs nearest the first day of autumn in the northern hemisphere.
In the Central Time Zone, the equinox occurs on September 22 from 2020 – 2030, except for 2027 when it occurs September 23. Here are the Harvest Moon dates for the same time interval:
Harvest Moons 2020-2030 (CDT) – Full Moons nearest the autumnal equinox
Notice that a nearly “pure” Harvest Moon occurs when the full moon and the equinox occurs on the same date in 2029.
Traditionally, the full moon’s light at this season aided the fall harvest that occurred at this time of year at mid-northern latitudes. In times before Daylight Saving Time, the sun set around 6 p.m. (standard time), when clocks became important.
During the harvest time work could run longer than the 12 hours of daylight. So any extra illumination would help during the long work days of the season.
The full moon is bright enough to illuminate the ground so that the human eyes can easily maneuver outside and continue to work without artificial light.
As daylight wanes after late September, the moon’s reflected sunlight was important to help harvesters reap the summer’s bounty.
There’s an astronomical reason for added moonlight at this time of year. Other astronomical concepts are important:
The moon’s is full when it is precisely 180° from the sun. On nights before the “official” full moon, it may look like its that phase; it is missing 1-2% of its full moon light.
The vernal equinox is the location of the sun in the sky on the first day of spring. The equinox is the origin (0,0) for at least two coordinate systems.
The autumnal equinox is the location of the sun on the first day of autumn. Its coordinates are 180° from the vernal equinox (180,0).
The celestial equator is the extension of the earth’s equator into the sky.
The ecliptic is the plane of the solar system. The sun seems to move along this great circle in the sky. The planets and moon appear to move near the ecliptic. The moon’s orbit is inclined 5° to the ecliptic.
Seeming to travel along the ecliptic, the sun crosses the celestial equator at the equinoxes. When the sun is farthest from the equator (23.5° north or south), the solstices occur.
The moon crosses the ecliptic twice a month. If the sun is located at the spot where the moon crosses, a solar eclipse occurs. If it crosses 180° from the sun’s location (full moon), a lunar eclipse occurs.
As the autumnal equinox approaches, the sun moves toward its namesake point in the sky. As the sun sets, the vernal equinox point rises. If the moon is approaching its full phase simultaneously – a rare occurrence – it is approaching the vernal equinox coordinates.
As the list above shows, the nearest full moon to the beginning of the fall season can occur several days before or after the equinox date.
The vernal equinox lacks bright stars nearby to indicate its location. (The north pole in the sky has Polaris nearby. Several bright stars – Regulus, Spica, Antares, Aldebaran, and Pollux – are near the ecliptic.) The equinox point is among the faint stars of Pisces, southeast of the “circlet” of dim stars that outlines the Western Fish of the constellation. The bright planets are sometimes nearby to provide cues for the invisible point’s location. During the evenings of harvest time in 2020, Mars is over 25° east of the equinox. During the 2022 Harvest Moon, Jupiter is about 5° east of the point. During 2024, Saturn is about 15° west of the equinox at harvest time; 2° west in 2025; and 12° east in 2026.
When the vernal equinox is near the eastern horizon, the plane of the solar system (ecliptic) makes a minimum angle with the eastern horizon. As the moon moves eastward, it covers the 13° segment of its orbit compared to the starry background. Compared to the horizon, the moon does not lose much altitude.
The moon revolves about 13° to the east each day. It rises later – about 50 minutes each day – and sets later. During the full moon at harvest time, the moon rises only about 30 minutes later on successive afternoons and evenings. This effect occurs for a few evenings after the full phase as well. Consequently, the Harvest Moon illuminates the landscape after sunset around this traditional harvest time.
As the gibbous phase occurs around the time of the autumnal equinox, begin to spot the nightly change of the moon compared to the horizon. The moon is slightly lower, not as much as the average nightly change, and seemingly a little farther north along the horizon.
This Harvest Moon effect can be observed anytime the vernal equinox is near the horizon and the moon is moving toward that important coordinate, even if the moon is at a waning crescent phase, such as near the time of the vernal equinox in March.
The Harvest Moon gets more notice because of its traditional agrarian role and the publicity the moon receives in the popular press, such as blue moon, supermoon, and such.
2020, September 2: Jupiter is 2.7°to the right of 50 Sagittarii (50 Sgr) and 2.2° to the lower left of Pi Sagittarii (π Sgr).
Jupiter and Saturn are easy to spot in September’s evening sky.
by Jeffrey L. Hunt
Bright Jupiter and Saturn shine from the south-southeast sky this evening. The two giant planets are well-placed for viewing during the early evening.
The planets are 8.3° apart in eastern Sagittarius. Both are retrograding – moving westward compared to the starry background.
As the planets revolve around the sun, they move eastward compared to the starry background. While they rise in the east and set in the west from Earth’s rotation, each night they appear farther eastward compared to the stars.
As Earth catches up to and passes between the planets and the sun, they appear to move backward compared to the stars. This illusion is similar to the classic train impression where the passenger cannot at first determine which train is moving, the one they are occupying or the one adjacent to them. One seems to be moving compared to the other and the background through the windows.
Both planets end their retrograde this month. Jupiter ends its apparent backward motion on September 12, followed by Saturn, September 28.
Then Jupiter somewhat quickly closes the gap between them until the Great Conjunction of the two planets on December 21, 2020. This is the closest conjunction since the meeting in 1623. While other Jupiter – Saturn conjunctions have occurred during the following centuries, this year’s promises to be spectacular in its closeness.
Follow the progress of the planets in the starfield with a binocular. Jupiter is near Pi Sagittarii (π Sgr on the photo) and 50 Sagittarii (50 Sgr). Saturn is near 56 Sagittarii (56 Sgr).
If held steadily, up to four of Jupiter’s satellites are visible. In the photo at least two are captured. They appear as dim stars to each side of the planet.
2020, September: Jupiter and Saturn: This chart displays the positions of Jupiter and Saturn among the stars of eastern Sagittarius on September 15. Jupiter is near Pi Sagittarii (π Sgr) and 50 Sagittarii (50 Sgr). Saturn is below 56 Sagittarii (56 Sgr).
This chart shows the positions of the planets compared to the stars mentioned above on September 15, 2020.
Mars is well-up in the eastern sky by 11 p.m. If you are outside during morning twilight, spot it high in the south. It’s the brightest “star” in the southern sky. On the evening of September 5 and the morning of September 6, the moon and Mars are close together in the sky.
2020, September 6: In the morning sky, the moon is 2.3° to the upper left of Mars.
On the night of September 5/6, the gibbous moon appears to guide the bright planet Mars.
2020, September 5: The moon and Mars, (Composite of two images)
Update: Photo from September 5, 2020.
by Jeffrey L. Hunt
On the night of September 5 – September 6, the gibbous moon appears near Mars, a very bright planet in the southern sky before sunrise. Currently, Mars is the fourth brightest “star” in the sky. Only, the moon, Venus, and Jupiter are brighter.
As Earth approaches Mars, the Red Planet brightens – during the next six weeks – although it is not much larger in appearance to the human eye. Even with a closest approach pending, the planet only resembles an overly bright star. While it can double in its apparent size through a telescope, the increase is imperceptible to the human eye (unlike what is shown in the social media memes.)
2020, September 5: Mars is 9.6° to the upper left of the lunar orb. Among the stars of Pisces, the Red Planet is 2.2° to the upper left of Nu Piscium (ν Psc) and 2.6° to the lower left of Omicron Piscium (ο Psc).
On the evening of September 5 and morning of September 6, the bright gibbous moon is near the Red Planet. Here’s what to look for on the night before and after the grouping:
September 5: One hour before sunrise, the bright gibbous moon is over 40° up in the southwest. The moon is over 91% illuminated. Mars is 9.6° to the upper left of the lunar orb. The separation is about the distance across your fist at arm’s length. In the evening, about three hours after sunset (10:15 p.m. CDT, in Chicago), the moon – about 86% illuminated – is to the lower right of Mars, about 0.8° away. That’s about the distance across two fingertips at arm’s length. Find them in the east. On these evenings find bright Jupiter and Saturn – to Jupiter’s upper left – in the south-southwest sky.
2020, September 6: Mars and Moon. (Composite image)
Update: Photo from September 6, 2020.
September 6: One hour before sunrise, the moon is over halfway up in the southwest. Mars is 2.3° to the lower right of the lunar orb. Three hours after sunset in the eastern sky, bright Mars is over 11° to the upper right of the moon that is 79% illuminated. The moon is near the eastern horizon.
September 7: One hour before sunrise, the bright moon – 77% illuminated – is less than 60° in altitude in the south-southwest. Mars is about 15° to the lower right of the moon.
Each night, the moon is farther east of Mars and it begins to approach Venus in the east in the morning sky. Look for the crescent moon and Venus on September 14.
Here is a daily summary about the planets during September.
