Category Archives: Sky Watching

The Harvest Moon

Full moon
Full Moon (NASA Photo)

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

  • October 1, 2020
  • September 20, 2021
  • September 10, 2022
  • September 29, 2023
  • September 17, 2024
  • October 6, 2025
  • September 26, 2026
  • September 15, 2027
  • October 3, 2028
  • September 22, 2029 (11:29 a.m. CDT); Autumnal Equinox (12:38 p.m. CDT)
  • September 11, 2030

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:

  1. The moon’s is full when it is precisely 180° from the sun.  On nights before the “official” full moon, it may look like it’s that phase; it is missing 1-2% of its full moon light.
  2. 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.
  3. 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).
  4. The celestial equator is the extension of the earth’s equator into the sky.
  5. 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.
  6. Seeming to travel along the ecliptic, the sun crosses the celestial equator at the equinoxes – those points in the sky where the imaginary ecliptic crosses the imaginary celestial equator.  When the sun is farthest from the equator (23.5° north or south), the solstices occur.
  7. 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.

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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.

Orion Rising, September 4, 2020

2020, October 24: Morning Star Venus, Evening Planets Mars, Jupiter, Saturn

Bright Morning Star Venus continues to sparkle in the eastern sky before sunrise. It shines from in front of the stars of Virgo. Evening planet Mars appears in the eastern sky while Jupiter and Saturn are in the south-southwest. The bright gibbous moon shines from the stars of Capricornus.

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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, September 2: Jupiter and Saturn Shine in Evening Sky

Jupiter and Saturn in Sagittarius, September 2, 2020
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.

Chart for Jupiter and Saturn, September 2020
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.

Venus is low in the eastern sky before sunrise.

Here is a daily summary about the planets during August and September.

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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 in morning sky, August 12, 2020

2020, October 22: Morning Star Venus in Leo, Evening Planets and Moon

Bright Mars is visible in the western sky before sunrise. Brilliant Venus makes its last appearance in Leo for this morning apparition. In the evening sky, the crescent moon is near Jupiter and Saturn, while bright Mars begins the night in the east-southeast.

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.

2020, September 5-6: Bright Mars, Moon

Moon and Mars, September 6, 2020
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.

Moon and Mars, September 5, 2020
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.)

Mars in Pisces, September 5, 2020
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.
Mars and Moon, September 6, 2020
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.

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Jupiter and Saturn in Sagittarius, October 4, 2020.

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 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, 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.

2020, August 30: Morning Sky Ablaze

Venus and the stars during morning twilight, August 30, 2020
2020, August 30: Venus and a bright contingent of bright stars – Castor, Pollux, Procyon, Sirius, Rigel and Betelgeuse appear in the morning sky.

During morning twilight, the sky is ablaze with Venus, Mars, Sirius, and bright stars.

by Jeffrey L. Hunt

The late August morning sky is on fire with Venus, Mars, and several bright stars.  In the image above, Venus appears in the eastern sky with Castor, Pollux, Procyon, Sirius, Betelgeuse, and Castor.  Now two weeks after its first appearance in the morning sky, Sirius is easy to locate in the east-southeast.

Mars in Pisces, August 30, 2020
2020, August 30: Mars continues to march eastward in Pisces. This morning the Red Planet is 1.6° to the upper left of Nu Piscium (ν Psc) and 2.7° below Omicron Piscium (ο Psc).

The Red Planet is high in the southern sky among the dim stars of Pisces.  The planet continues to brighten as Earth approaches it.  Mars is less than 47 million miles away this morning.

Mars continues its eastward march among the stars.  On September 9, Mars seems to end its eastward direction and appears to move westward compared to the stars, in what is known as retrograde motion.  This is an illusion from our faster moving world overtaking a slower moving Mars and passing between the Red Planet and the sun, known as opposition (October 13, 2020).

Additionally, Mars orbit is not a perfect circle. A week before opposition, Earth and Mars are closest when they are about 39 million miles apart.  Even at this distance, Mars looks like an overly bright star in the sky.

In the photo above, Mars is 1.6° to the upper left of Nu Piscium (ν Psc) and 2.7° below Omicron Piscium (ο Psc).  East is to the left in the image, Mars continues to move eastward past ν Psc before it begins to retrograde.  When Earth and Mars are closest, the Red Planet appears near μ Psc.

Venus in Gemini, August 30
2020, August 30: Venus is is to the lower right of Pollux. The planet is 4.2° below Delta Geminorum (δ Gem) and 5.0° to the lower left of Lambda Geminorum (λ Gem).

Farther east, Venus sparkles from in front of the stars of Gemini.  It continues stepping eastward compared to the starry background.  This morning it is to the lower right of Pollux.  On the photo, the planet is 4.2° below Delta Geminorum (δ Gem) and 5.0° to the lower left of Lambda Geminorum (λ Gem).

Tomorrow morning, Venus makes a wide pass (8.6°) of Pollux.  Early next month, the planet moves into Cancer and a nice grouping with the moon and the Beehive star cluster on September 14.  It’s another camera-ready morning to see.

Here is a daily summary about the planets during August and September.

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Full moon

2020, October 17: Moon Returns to Evening Sky

A New moon is visible low in the western sky after sunset. Venus, Mars, Jupiter, and Saturn are visible during the night. Jupiter continues to close the gap to Saturn before the Great Conjunction of 2020.

Venus and Jupiter, August 18, 2012

2020, October 16: Winter Triangle in South

The Winter Triangle is in the south before sunrise. During the nighttime hours four bright planets are visible: Venus, Mars, Jupiter, and Saturn.

Venus from Galileo (NASA photo)

2020, October 15: Skies for Ides of October

Four planets are visible on October 15. Venus and Mars are in the morning sky. Mars returns to the sky during the early evening along with Jupiter and Saturn.

2020, September: Venus Sparkles in Eastern Morning Sky

Venus during September 2020
Venus during September: Venus moves from Gemini, through Cancer, and into Leo. Spot the brilliant planet near the Beehive cluster at mid-month.

 

Venus continues to shine as a Morning Star in the eastern sky during September.

by Jeffrey L. Hunt.

  • Venus in Leo, September 25, 2020
  • Venus with bright stars, September 18, 2020
  • Venus in Cancer, September 18, 2020
  • Venus and Moon, September 14, 2020
  • Venus and Moon, September 14, 2020
  • Venus and the stars during morning twilight, September 5, 2020
  • Venus moves into Cancer, September 4, 2020
  • Venus in Cancer, September 5, 2020
  • Venus moves into Cancer, September 4, 2020
  • 2020, September 4: Venus, Sirius, Procyon, and Orion

Click an image to see a slideshow of Venus images for September 2020.

As the days noticeably shorten, Venus continues its spectacular appearance in the eastern morning sky.

See our feature about Venus in the morning sky.

The chart above shows the motion of the planet compared to the starry background.

On September 1, Venus rise nearly 3.75 hours before sunrise, and it is high above the skyline as morning twilight brightens the eastern sky.  By month’s end it rises nearly 3.5 hours before sunrise.  So, it remains “that bright star” in the eastern sky.

During September the planet is in eastern Gemini and it continues to work its way eastward through the zodiacal constellations.  During the month, the planet moves into Cancer with its dimmer stars.  Near month’s end it moves into Leo.

As Earth revolves around the sun, the stars rise about 4 minutes earlier each morning.  During the course of a month, they rise two hours earlier by month’s end.  This slow westward march of the constellations helps us mark the seasons in the sky.

As the stars rise earlier, Venus steps eastward each morning.  Consequently, it is nicely placed in the sky to be easily noticed.

In the sky, Venus keeps nearly a constant spot and the stars seem to move past it when observed at the same time each morning.

Early in the month, Saturn departs the sky as Venus rises, leaving Venus and Mars in the morning sky.

On the morning of September 14, the crescent moon and Venus appear near the Beehive star cluster.  While not as bright as the famous Pleiades star cluster, the Beehive appears as a fuzzy cloud.  A binocular provides a good view of the cluster.

The bright planet then continues to glide eastward toward Leo, stepping into the constellation on September 23.

Even with the planet’s brilliance, use a binocular to track it through the starfield.

In the notes that follow the “m” numbers indicate the brightness of Venus and the stars.  The smaller the number, the brighter the star or planet.  Venus has a negative number to show its brilliance. The stars with magnitude 1 are among the brightest in our sky.  As the number increases toward 4 and 5, they are among the dimmer stars visible to the unaided eye.  Some of the stars have Greek letters designating their names. When the letter of the star and its genitive name are used, a star like Pollux is also known as Beta Geminorum (β Gem) to indicate that its Beta in the constellation Gemini. Additionally, with the Greek letter, the constellation is abbreviated, Gemini (Gem), Cancer (Cnc).

Numbers are used to name stars when the Greek alphabet is exhausted, like 81 Geminorum or 20 Cancri.

Detailed daily notes for observing planets are found here. In the notes that follow, the observations are for one hour before sunrise, when Venus is about 30° up in the sky; that’s about one-third of the way from the natural horizon to overhead.

Venus, Moon, Beehive, September 14, 2020
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.
  • September 1: One hour before sunrise brilliant Venus (m = −4.3) is less than 30° up in the east in Gemini.  It is 8.6° to the lower right of Pollux (m = 1.2).  With a binocular notice that it is below a line that connects Pollux and Kapa Geminorum (κ Gem, m = 3.6) and extends downward to Procyon (α CMi, m = 0.4).
  • September 2:  Venus (V) rises as Saturn sets.  The morning sky now has two bright planets – Venus and Mars.
  • September 3: V is 0.9° to the right of 85 Geminorum (85 Gem, m = 5.4).
  • September 4: V moves into Cancer, over 9° to the lower right of Pollux and over 11° to the upper right of Delta Cancri (δ Cnc, m = 3.9). 
  • September 7:  V is 0.9° to the upper left of Zeta Cancri (ζ Cnc, m = 5.2). Use a binocular.
  • September 10:  V is 0.5° below 20 Cancri (20 Cnc, m = 5.9).
  • September 11: V is 0.5° to the upper right of Theta Cancri (θ Cnc, m = 5.3).  Use a binocular to spot the Beehive cluster to the lower left of Venus.  The cluster appears as a patch of stars, like sparkling jewels on the velvet of the sky.
  • September 12: Through a binocular, V is 2.5° to the right of the Beehive cluster. The moon (24.3 days past the New Moon phase, 30% illuminated), nearly 50° up in the east and over 20° above V.  The lunar orb is over 10° to the upper right of Castor (α Gem, m =1.6).
  • September 13:  V passes 2.3° to the lower right of the Beehive cluster. The planet is also 1.5° to the upper right of δ Cnc. The waning crescent moon (25.3d, 20%) is over 10° above V.
  • September 14: V 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 V and 4.6° to the upper right of the lunar crescent.
  • September 15: V 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 V.  The moon (27.2d, 6%) is about 15° up in the east.
  • September 16: V is 4.2° below the Beehive cluster, 2.3° below δ Cnc, and 1.8° to the upper left of Omicron Cancri (ο Cnc, m =5.2).
  • September 21: V is 0.5° to the upper left of Pi Cancri (π Cnc, m = 5.3).
  • September 23: V moves into Leo, 11.0° to the upper right of Regulus (α Leo, m = 1.3).
  • September 25: V passes 3.1° to the upper left of Xi Leonis (ξ Leo, m = 5.0).
  • September 28: V passes 3.8° to the upper left of Omicron Leonis (ο Leo, m = 3.5).
  • September 30: V ends the month 0.4° above Nu Leonis (ν Leo, m = 5.2) and 2.9° to the upper right of Regulus.

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2020, October 7: Morning Star Venus, Mars, Moon

Brilliant Venus, bright Mars, and the gibbous moon shine brightly in the morning sky. Mars shines from Pisces in the western sky. Venus is “that bright star” in the east before sunrise.

The crescent moon, September 15, 2020

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2020, August 28-29: Jupiter, Saturn, Moon in Evening Sky

The moon and Mars, February 18, 2020
2020, February 18: The moon is near Mars before sunrise.

The bright moon appears near Jupiter and Saturn on the evenings of August 28 and August 29.

by Jeffrey L. Hunt

Four bright planets – Jupiter, Saturn, Mars, and Venus – are visible between sunset and sunrise.

The planets appear as overly bright stars in the sky.

Bright Jupiter appears in the southeastern sky after sunset.  Dimmer Saturn is to the Giant Planet’s lower left.

Of all the celestial objects, the moon moves fastest eastward compared to the stars.  It travels through one orbit in less than 30 days as it nearly displays all its phases.

Jupiter, Saturn, Moon, August 28, 2020
August 28: In the evening sky, Jupiter is 2.2° above the moon. Saturn, 8.3° to the left of Jupiter, is 8.8° to the upper left of the moon.

On the evening of August 28, the lunar orb, distinctly a gibbous shape (83% illuminated), is low in the south-southeast.  Bright Jupiter is 2.2° above the moon and Saturn is 8.3° to the left of Jupiter.

Jupiter, Saturn, Moon, August 29, 2020
August 29: One hour after sunset, Saturn is 5.7° to the upper right of the moon and 8.3° to the left of Jupiter that is over 13° to the upper right of the gibbous moon.

On the next evening (August 29), the moon is farther eastward and with a larger phase (90% illuminated).  Saturn is 5.7° to the upper right of the gibbous shape and 8.3° to the left of Jupiter.  The Giant Planet is over 13° to the upper right of the moon. 

Now over a month after our planet passed between Jupiter and Saturn (opposition), these planets are easily visible in the evening sky.

When held steadily, a binocular can reveal any number of Jupiter’s four largest moons.   A small telescope can show stripes in Jupiter’s clouds.  A careful inspection of Saturn with a small telescope reveals its ring and perhaps a cloud band or two in its atmosphere.

Because of the planets’ stellar appearance, the earliest astronomers recognized these special stars had the power of movement, compared to the multitude of “fixed” stars in the constellations.

Normally, the planets appear to move eastward compared to the starry background. As Earth approaches them in its celestial orbit; moves between them and the sun; and recedes from the worlds, the planets appear to move backwards or retrograde compared to the starry background.

Jupiter and Saturn are retrograding in front of the stars of Sagittarius.  Jupiter’s eastward direction resumes on September 12, while Saturn returns to its eastward direction on September 28.

Jupiter then approaches and passes Saturn on December 21, 2020, in a once-in-a generation Great Conjunction.  Of the large count of Great Conjunctions during the centuries, this is the closest conjunction since the grouping in 1623.

Mars rises later in the evening and it is well up in the east as midnight approaches.  At this time, Jupiter and Saturn are in the southwestern sky. 

Mars begins its retrograde direction on September 9.  Earth passes between the Red Planet and the sun on October 13, 2020.  Near opposition, Mars outshines everything in the night sky except for Venus and the Moon.

Venus rises before morning twilight begins and it is “that bright star” in the east before sunrise. Venus, Mars, and Saturn are in the sky together shortly after Venus rises, but the Ringed Wonder shortly disappears below the horizon.

Saturn is no longer visible in the sky with Venus after early September as Venus moves eastward more rapidly than Saturn, that is still retrograding at that time.

Then Venus and Mars are in the morning sky together until November when Mars sets as Venus rises.

Jupiter and Saturn, August 21, 2020
2020, August 21: Jupiter is 2.4° to the lower left of Pi Sagittarii (π Sgr) and 2.2° to the lower right of 50 Sagittarii (50 Sgr). On for the next few weeks, watch Jupiter move closer to π Sgr and farther from 50 Sgr.

The photo above shows Jupiter and Saturn on the evening of August 21, 2020.

Look at the starfield around Jupiter and Saturn with a binocular.  Jupiter is to the lower left of Pi Sagittarii (π Sgr on the photo) and to the lower right of dimmer 50 Sagittarii (50 Sgr).  Jupiter continues to move to the right (west) compared to the stars, moving closer to π Sgr and a little farther from 50 Sgr.

Meanwhile, Saturn is moving westward below 56 Sagittarii (56 Sgr).  By the end of September Saturn is nearly below the star.

Here is a daily summary about the planets during August and September.

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2020: August 22: Jupiter, Saturn, Bright Evening Planets

Jupiter and Saturn, August 21, 2020
2020, August 21: Jupiter is 2.4° to the lower left of Pi Sagittarii (π Sgr) and 2.2° to the lower right of 50 Sagittarii (50 Sgr). On for the next few weeks, watch Jupiter move closer to π Sgr and farther from 50 Sgr.

Jupiter and Saturn shine brightly in the southern skies before midnight.

by Jeffrey L. Hunt

Bright Jupiter and Saturn shine from the southern skies before midnight.  They appear low in the southeast as the sky darkens after sunset.

The brightest planets appear as overly bright stars in our sky.  They rise in the east and set in the west each day along with the other stars, sun, and moon.

As the planets revolve around the sun, they move slightly eastward as compared to the starry background.

There are times when our faster moving planet approaches, passes, and moves away from the planets outside Earth’s orbit.  These outer planets seem to move westward compared to the background of stars.  This retrograde motion is an illusion. 

The planets’ retrograde motions are displayed before and after the outer planets are at opposition, when Earth is between the sun and the planet. At this time, the planets are near their closest points to Earth.  The sun and planets are in opposite directions in the sky. The distant worlds shine brightly in our sky all night.

Jupiter was at opposition on July 13 and Saturn followed a week later.  Mars is approaching its opposition on October 13, 2020.  It is closest to Earth a week earlier.

Jupiter and Saturn are retrograding.  Jupiter’s retrograde ends September 12 and Saturn, September 28.  Mars begins to retrograde September 9.  It is the bright star high in the south before sunrise.  (Venus is “that brilliant star in the east” as the morning twilight brightens.)

Watch Jupiter and Saturn continue to retrograde.  On the image above, Jupiter is 2.4° to the lower left of Pi Sagittarii (π Sgr) and 2.2° to the lower right of 50 Sagittarii (50 Sgr). For the next few weeks, watch Jupiter move closer to π Sgr and farther from 50 Sgr.

Saturn is 2.0° to the lower left of 56 Sagittarii (56 Sgr).  Watch it move beneath the star before its retrograde ends at the end of September.

Look for Venus and Mars in the morning before sunrise.

Over a week after its first appearance (heliacal rising) in the morning sky, Sirius, the night’s brightest star, shines from the east-southeast nearly 45 minutes before sunrise.

Here is a daily summary about the planets during August.

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2020, August 21: Sirius Shines in Morning Twilight

Sirius, August 21, 2020
2020: August 21, 2020: Sirius shines from low in the east-southeast during morning twilight. Brilliant Venus is higher in the sky in the east.

Sirius, the night’s brightest star, shines from the east-southeast before sunrise.

by Jeffrey L. Hunt

About a week after its first appearance (heliacal rising) in the morning sky, Sirius, the night’s brightest star, shines from the east-southeast nearly 40 minutes before sunrise.

As seen in the image above, Sirius is low in the sky.  Find an observing spot reasonably free of obstacles to see the star. It is easily visible without a binocular or telescope.  As the star rises 4 minutes earlier each day, find in higher in the east-southeast at the same time in about a week.

Here is a daily summary about the planets during August.

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2020, August 21: Mars Gleams in Morning Sky

Astronomy
This self-portrait of NASA’s Curiosity Mars rover shows the vehicle on Vera Rubin Ridge, which it’s been investigating for the past several months. Poking up just behind Curiosity’s mast is Mount Sharp, photobombing the robot’s selfie. Image credit: NASA/JPL-Caltech/MSSS

Bright Mars shines from the southern sky before sunrise.

by Jeffrey L. Hunt

Mars is the bright “star” in the southern sky before sunrise.  It complements the brilliant Venus that shines in the east.  Mars has been part morning planet parade that has included Saturn and Jupiter.

Mars is approaching its opposition (October 13) and its closest approach to Earth (October 6). 

At opposition, the Red Planet rises in the east as the sun sets in the west.  The planet is in the southern sky around midnight, and it sets in the west as the sun rises in the east.  The sun and Mars are in opposite directions in the sky.

In history, astronomers have been attracted to the nearly biennial Martian opposition.  At these times the planet presents itself for excellent telescopic inspection.  The planet’s moons were first observed during the opposition of 1877.  At the same opposition Giovanni Schiaparelli sketched Martian features, including “canali.”   Robot spacecraft are launched toward Mars near opposition because the planets are close together, travel times are relatively short, and minimal rocket fuel is needed.  NASA’s Perseverance rover was launched July 30.  The craft’s planned arrival is mid-February 2021.

Because the Martian planetary orbit is not a perfect circle, the planet is closest to Earth a week before its opposition, shining brightly all night.  Currently, the planet rises at about 10 p.m. and is high enough to be easily seen about an hour later.

Early in September, Mars begins to retrograde – move westward compared to the starry background.  This is an illusion as our faster moving Earth catches and passes Mars and the other planets.  Every object in the solar system – except the sun – appears to retrograde from the combined orbital patterns of Earth and the other bodies.

Mars in Pisces, August 21, 2020
2020, August 21: The Red Planet is 0.5° to the upper right of Nu Piscium (ν Psc) and 2.3° to the left of Mu Piscium (μ Psc).

Mars is currently moving eastward compared to the dim stars of Pisces.  It is 0.5° to the upper right of Nu Piscium (ν Psc on the photo) and 2.3° to the left of Mu Piscium (μ Psc).

As an aside, the separation between Mars and ν Psc is about the diameter of the full moon.  If the moon were in the sky this morning, it could appear between the planet and the star, as seen in the sky.

This evening, locate Jupiter and Saturn in the southeastern sky after sunset.

Here is a daily summary about the planets during August.

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Mars at opposition, 2016 and 2018

2020, October: Look For Bright Mars

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. This is the closest distance to Mars until 2035. The moon passes the planet twice, October 2 and October 29.

2020, August 20: Venus and Orion, Morning Sky

Venus and Orion

Brilliant Venus and Orion shine from eastern morning sky

by Jeffrey L. Hunt

Brilliant Venus continues to put on a planetary display in the morning sky.  It appears in front of the stars of western Gemini.

As Venus rises above the tree line, Orion, with its bright stars Betelgeuse and Rigel, appears to the right of the sparkling planet.

Aldebaran appears above the scene.  Venus appeared near that star about a month ago.  The planet has moved farther eastward since then.

Venus in eastern Gemini

Among the stars, Venus is 4.8° to the left of Gamma Geminorum (γ Gem on the photo) and 3.0° to the upper right of Zeta Geminorum (ζ Gem).

This evening, locate Jupiter and Saturn in the southeastern sky after sunset.

Here is a daily summary about the planets during August.

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