Category: Feature

Astronomy, Feature, Sky Watching

2020, June: Solstice and Bright Morning Planets
Day Lilly
June 20: The flowers celebrate the beginning of summer.

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Link to the summary of the moon and planets in the morning sky.

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June’s Planet Images

by Jeffrey L. Hunt

(Important Note:  These daily notes are written for Chicago, Illinois.  Observers should make any necessary adjustments for longitude differences, time zone corrections, and latitude differences.)

At the beginning of twilight (3:10 a.m. CDT), the Scorpius and Sagittarius section of the sky is at its full glory at the sky’s meridian. From the Scorpion’s classic pincers (Libra) in the southwest, and back to the heart (Antares) that leads us to the stinger that is at the imaginary celestial divider that separates the rising stars from the setting stars. Sagittarius is just east of the meridian. Its famous Teapot shape is in full view with the nebulae of the Milky Way above its spout. At this hour, bright Jupiter and Saturn are in the southeast to the east of the Teapot. The splendor of the Milky Way is muted by the gibbous moon’s light that is low in the west in Virgo. Spica is in the west-southwest with Arcturus high in the west. The Big Dipper is low in the northwest with its Pointers reliably aiming northward. Leo leans toward the western horizon. Its Sickle is punctuated by regal Regulus. Facing east, we see that the Summer Triangle – Vega, Deneb, and Altair – is high in the sky. If it were not for the moon’s interfering light, we could trace the Milky Way from the south past Cygnus and Deneb to the north-northeast horizon with Perseus and Cassiopeia. Below the Summer Triangle, Pegasus and Andromeda come into view. If you’re impatient to see the Great Andromeda Spiral, then you can find it about 20° up in the northeast. You’ll need to fight the light of the bright moon. On June 1st, the sun’s arc carries it across the sky in a few minutes longer than 15 hours. Twilight totals about 4.25 hours that is divided between morning and evening. Darkness, the interval of time when the sky is completely dark, lasts only 4.75 hours. At the end of twilight (10:30 p.m. CDT), golden-orange Arcturus is over two-thirds of the way up in the sky at the meridian. On June 1st, the moon is above Spica, about 10° west of the meridian. Back in the eastern sky, Antares is low in the southeast. The Summer Triangle is above the horizon in the east, signaling that summer’s start is near. Along the horizon toward the north, Cassiopeia is low in the sky, east of the meridian. The three remaining stars of winter are in the northwest – Capella, Castor and Pollux. They disappear from the evening sky this month, but Capella is back in the sky before sunrise.

Three bright planets – Mars, Jupiter, and Saturn – are scattered across the sky from southeast to south before sunrise. Jupiter and Saturn continue to retrograde as Jupiter slowly backs away from Saturn. Brilliant Venus begins its morning show before mid-month. Don’t miss the close grouping of Venus and the crescent moon on June 19. After sunset, Mercury is completing its evening apparition, where it appeared with Venus, the moon, and Elnath during May.

  • June 1: Jupiter (m = −2.6) and Saturn (m = 0.4) rise before midnight and they are very low in the east-southeast as the new day begins. Both planets are retrograding. Mars (m = 0.0) rises at 1:40 a.m. CDT. Jupiter is in eastern Sagittarius, and Saturn appears in front of the stars of western Capricornus. One hour before sunrise, the Bright Outer Planets – Mars, Saturn, and Jupiter – span nearly 47°. Jupiter, over 27° up in the south, is 4.8° to the lower right of Saturn. Jupiter appears west of the meridian at this time interval. Saturn appears west of that line in a few mornings. Among the stars, Jupiter is 2.2° to the lower left of 56 Sagittarii (56 Sgr, m = 4.8). Saturn is 1.4° to the lower right of Sigma Capricorni (σ Cap, m = 5.2). Farther east, Mars is over 25° in altitude in the southeast. Among the stars, Mars is 2.2° to the lower left of Lambda Aqaurii (λ Aqr, m = 4.8). Watch the movement of Jupiter, Saturn, and Mars in their starry backgrounds with a binocular. The sun is in the sky for a few minutes longer than 15 hours. Darkness – the time between the end of evening twilight and the start of morning twilight – is 30 minutes longer than the sum of the length of morning twilight and evening twilight. Forty-five minutes after sunset, Mercury (m = 0.3) is nearly 11° in altitude in the west-northwest. Mercury dims as its appearance continues. Use a binocular to find and follow the speedy planet during the next several evenings. As the sky darkens further, the moon (10.4 days past the New phase and 82% illuminated), nearly halfway up in the sky in the south, is 6.6° above Spica (α Vir, m = 2.0).
  • June 2: One hour before sunrise, Jupiter is over 27° up in the south and west of the meridian. Saturn is 4.8° to the upper left of Jupiter. Both planets are retrograding. In particular, note Jupiter’s movement relative to 56 Sgr. Jupiter is 2.2° to the lower left of that star. Farther east, Mars is nearly 26° up in the southeast, 2.6° to the lower left of λ Aqr and 4.0° to the lower right of Phi Aquarii (φ Aqr, m =4.2). Use a binocular to see the planets among the stars. Forty-five minutes after sunset, Mercury (m = 0.4) is nearly 11° in altitude in the west-northwest. Fifteen minutes later, the bright moon (11.4d, 90%) is 9.2° to the upper right of Zubenelgenubi (α Lib, m = 2.8). The moon is at perigee at 10:38 p.m. CDT. It is 226,406 miles away.
  • June 3: Mars (m = −0.1) is 26° up in the southeast, one hour before sunrise. In the starfield, it is 3.1° to the lower left of λ Aqr and 3.4° to the lower right of φ Aqr. Farther west, bright Jupiter is over 27° up in the south, west of the meridian. Saturn is 4.9° to the upper left of Jupiter. Tomorrow morning, Saturn is west of the meridian at this time interval. Venus is at inferior conjunction at 12:44 p.m. CDT. Forty-five minutes after sunset, Mercury (m = 0.5) is less than 11° up in the west-northwest. Use a binocular to track Mercury during this apparition as it is dimmer each evening. As the sky darkens further, the nearly Full Moon (12.4d, 96%) is 6.2° below Zubeneschamali (β Lib, m = 2.6). You may have to block the moon’s light or use a binocular to see the starfield.
  • June 4: One hour before sunrise, Jupiter is 27.0° up in the south, west of the meridian. It is 4.9° to the lower right of Saturn, now west of the meridian at this time interval before sunrise. Jupiter is 2.1° to the lower left of 56 Sgr. Farther east, Mars is over 26° up in the southeast, 2.8° to the lower right of φ Aqr. Mercury is at its greatest eastern elongation (23.6°) at 8:07 a.m. CDT. Forty-five minutes after sunset, find Mercury (m = 0.6) over 10° up in the west-northwest. Use a binocular. As the sky darkens further, the moon (13.4d, 99%), over 16° up in the southeast, is 7.1° above Antares (α Sco, m = 1.0).
  • June 5: One hour before sunrise, the moon (13.6d, 100%) – 8.0° up in the southwest – is to the upper right of Antares. The star is near the horizon, less than 4° in altitude. Locate a clear horizon to see it. Farther east in the southern sky, bright Jupiter is 4.9° to the lower right of Saturn. In the starfield, Jupiter is 2.0° to the lower left of 56 Sgr, while Saturn is 1.6° to the lower right of σ Cap. In the southeast, Mars is nearly 27° up in the sky. It has a higher altitude than Jupiter, but lower than Saturn, at this time interval. In the starfield, the Red Planet is 2.3° to the lower right of φ Aqr. Fomalhaut (α PsA, m = 1.2) – 10° up in the south-southeast – is becoming easier to see at this time interval. The star is nearly 22° to the lower right of Mars. The moon reaches its Full phase at 2:12 p.m. CDT. A penumbral lunar eclipse is visible in parts of Australia, southern Asia, eastern Europe, and eastern Africa. Clearly nothing for us to observe at our longitude. Forty-five minutes after sunset, Mercury (m = 0.7) is over 10° up in the west-northwest. Two hours after sunset (approximately 10:30 p.m. CDT), the moon (14.4d, 100%) is over 14° up in the southeast.
  • June 6: One hour before sunrise, the bright moon (14.6d, 100%) is over 13° up in the southwest. Farther east, Jupiter is less than 27° up in the south. It is 4.9° to the lower right of Saturn and 2.0° to the lower left of 56 Sgr. Use a binocular to see the starfield. Farther east, Mars – over 27° up in the southeast – is 1.8° to the lower right of φ Aqr and 1.1° to the upper right of Chi Aquarii (χ Aqr, m = 4.9). A binocular helps see the dimmer stars with Mars, especially with the bright moon in the sky. In the evening, one hour after sunset, Mercury (m = 0.8) is less than 10° up in the west-northwest. Three hours after sunset (about 11:30 p.m. CDT), the moon (15.4d, 97%) is nearly 13° up in the southeast, 1.4° to the upper right of Kaus Borealis (λ Sgr, m = 2.8), the star at the top of the lid of the Teapot of Sagittarius. Block the moon’s glare or use a binocular to see the star.
  • June 7: One hour before sunrise, the moon (15.6d, 97%) – over 18° up in the south-southwest – is 0.9° to the upper left of Kaus Borealis. In the south, Jupiter is over 26° in altitude. Saturn is 5.0° to the upper left of Jupiter, as both planets continue to retrograde. Farther eastward along the ecliptic, Mars is nearly 28° up in the southeast, nearly midway from φ Aqr to χ Aqr. It is about 1.5° from each star. After sunset, Mercury (m = 0.9) is nearly 10° up in the west-northwest. Use a binocular to see it.
Jupiter, Saturn, Moon, June 8, 2020.
2020, June 8: The moon is 5.8° to the lower right of Jupiter. The Jupiter – Saturn gap is 5.0°.
  • June 8: One hour before sunrise, the moon (16.6d, 92%) – about 22° up in the south-southwest – is 5.8° to the lower right of bright Jupiter. The Jupiter – Saturn gap is 5.0°. In the starfield, Jupiter is 1.9° to the lower left of 56 Sgr. Farther east, Mars – over 28° up in the southeast – is 1.5° below φ Aqr and 0.3° to the upper left of χ Aqr. Forty-five minutes after sunset, dimming Mercury (m = 1.0) is over 9° up in the west-northwest. Procyon (α CMi, m = 0.4) is over 5° up in the west. It is making its last appearance at this time interval. Can you find it without optical assistance? This month let’s look for my favorite five double stars rather than deep sky objects. All the stars on the list are brighter stars and can be used to introduce new observers to the sky’s wonders. First, Mizar (ζ UMa, m = 2.2) and Alcor (80 UMa, m = 4.0) are located at the bend of the Big Dipper. The group is high in the northwest at the end of evening twilight. The two stars are not connected, but they appear along the same line of sight. While the Big Dipper never sets at our latitude, the group is high in the sky at this season; so, I list it with my warmer weather double stars to observe. For some civilizations (cited in Burnham’s Celestial Handbook), the pair was used as a test of eyesight. Those persons with sharp eyes could easily see both stars. They are separated by nearly 0.2°. That is twice the separation of the upcoming Jupiter – Saturn Great Conjunction in December. Alone, Mizar is a double star. The 4th magnitude component is only 14” away from the brighter star. Burnham reports that Mizar was the first double star observed. Star color of doubles provides an opportunity to test our visual acuity. Burnham writes that the dimmer companion is sometimes reported as “pale emerald” (p. 1953) in color. What do you see? Alcor by itself is a double, but the second star is not easily observed. The 8th magnitude red dwarf is only 1” away from the brighter star. The second star on my list is Gamma Virginis (γ Vir, m = 3.4). The star is over 14° west of Spica. Only about 3° north of the ecliptic, the moon frequently appears near the star. The companion is nearly the same brightness and about 4” from the main star, and the pair has nearly the same color. The companion revolves around the main star in about 170 years. The third star is Beta Scorpius (β Sco, m = 2.5). The companion is 5th magnitude and is nearly 14” away. Like Mizar’s companion, β Sco’s companion has been reported to be green. My experience is that most observers do not see the color. It’s a good conversation starter at a telescope session. The fourth star is Epsilon Lyrae (ε Lyr, m = 4.6). This famous double makes a triangle with Vega and Zeta Lyrae (ζ Lyr, m = 4.3). The “Double-double” is unimpressive to many beginners. Through a binocular or a finder, the first double appears. These stars are 3.5’ apart. Each of these stars resolves into double stars. Depending on the sky’s clarity and the collimation of my telescope, I may be able to resolve each brighter star. The final star on the list is Alberio (β Cyg, m = 3.0). It marks the nose of Cygnus. It is nearly midway from Vega to Altair. On my list this is the finest double in the sky. The pair has a breath-taking color difference, described as topaz and sapphire. The separation is over 30”. This is an exemplary double star to show to a beginning observer or just to revisit!
Moon to the lower left of Saturn, June 9, 2020
2020, June 9: One hour before sunrise the gibbous moon is 4.8° to the lower left of Saturn.
  • June 9: One hour before sunrise, Mars – over 28° up in the southeast – has a higher altitude than Saturn at this time interval. Saturn is in the south about 5° west of the meridian and 5.0° to the upper left of bright Jupiter. The moon (17.6d, 85%) is 4.8° to the lower left of Saturn. In the starfield, Mars is 1.7° to the lower left of φ Aqr and 0.9° to the left of χ Aqr. Jupiter is 1.9° to the lower left of 56 Sgr. Forty-five minutes after sunset, Mercury (m = 1.1) is over 8° up in the west-northwest.
  • June 10: Mars rises at 1:20 a.m. CDT. One hour before sunrise, the moon (18.6d, 77%) is over 27° up in the south-southeast. Bright Jupiter is at about the same altitude in the south-southwest, 5.1° to the lower right of Saturn (m = 0.3). In the starfield, Jupiter is 1.8° to the lower left of 56 Sgr, and Saturn is 1.7° to the lower right of σ Cap. Farther east, Mars is nearly 29° up in the southeast. Among the stars, the Red Planet is 2.1° to the lower left of φ Aqr and 1.5° to the left of χ Aqr. A binocular helps locate the three planets in their star fields. Mars is heading into a much dimmer starfield with 6th and 7th magnitude stars that has Neptune (m = 7.9). Venus rises at Civil Twilight, 32 minutes before sunrise. Forty-five minutes after sunset, Mercury (m = 1.2) is over 8° in altitude in the west-northwest. Jupiter rises at 10:40 p.m. CDT; Saturn follows about 20 minutes later.
  • June 11: In ecliptic longitude, the Jupiter – Mars gap is about 54°. One hour before sunrise, the gibbous moon (19.6d, 68%), in western Aquarius, is nearly 28° up in the south-southeast. Mars – about 20° to the left of the moon – is over 29° up in the southeast, 2.1° to the lower right of Neptune. Farther west along the ecliptic, bright Jupiter is 26.0° up in the south-southwest, 5.1° to the lower right of Saturn. In the starfield, Jupiter is 1.8° to the lower left of 56 Sgr. Forty-five minutes after sunset, use a binocular to locate Mercury (m = 1.3), over 7° up in the west-northwest.
  • June 12: One hour before sunrise, the moon (20.6d, 58%) – about 27° in altitude in the southeast – is 8.5° to the lower right of Mars. The Red Planet is 1.7° to the lower right of Neptune. Farther west, Jupiter is nearly 26° up in the south-southwest, 5.1° to the lower right of Saturn. Begin looking for the Pleiades, about 5° up in the east-northeast. Use a binocular to initially locate them. Can you see them without optical help? Continue to look during the next several clear mornings. What is the first date that you see the star cluster. Forty-five minutes after sunset, dim Mercury (m = 1.5) is nearly 7° up in the west-northwest. Jupiter rises at 10:30 p.m. CDT, about 130 minutes after sunset.
The moon and Mars, June 13, 2020
2020, June 13: The Last Quarter moon is 4.9° to the lower left of Mars.
  • June 13: The moon reaches its Last Quarter phase at 1:24 a.m. CDT. One hour before sunrise, the moon (21.6d, 49%) is 4.9° to the lower left of Mars. This morning Mars is 1.6° below Neptune. Farther west, bright Jupiter – nearly 26° in altitude in the south-southwest – is 5.2° to the lower right of Saturn. Both planets continue to retrograde as the gap between the two bright giants opens slowly. In the starfield, Jupiter is 1.7° to the lower left of 56 Sgr. Forty-five minutes after sunset, fading Mercury (m = 1.6) is over 6° up in the west-northwest.
  • June 14: One hour before sunrise, Jupiter is over 25° up in the south-southwest, 5.2° to the lower right of Saturn and 1.7° to the lower left of 56 Sgr. Farther east, Mars is over 30° in altitude in the southeast, 1.7° to the lower left of Neptune. The moon (22.6d, 39%), in Cetus, is over 20° up in the east-southeast. The moon is at apogee at 7:57 p.m. CDT. It is 251,261 miles away. Forty-five minutes after sunset, Mercury (m = 1.7), far below Castor and Pollux, is 5.5° up in the west-northwest.
  • June 15: Mars rises a few minutes after 1 a.m. CDT. The moon (23.6d, 30%) is over 20° up in the east-southeast. It is in Cetus for a second morning. Mars – nearly 31° up in the southeast – is to the upper right of the thick lunar crescent. The Red Planet is 2.0° to the lower left of Neptune. Farther west along the ecliptic, Saturn is over 27° in altitude in the south-southwest. It is 5.3° to the upper left of bright Jupiter. Among the stars, Jupiter is 1.7° to the lower left of 56 Sgr, and Saturn is 2.0° to the lower right of σ Cap. Thirty minutes later, Venus (m = −4.3) is over 3° up in the east-northeast. Through a telescope, Venus is 5% illuminated – a morning crescent – that is 54” across. Forty-five minutes after sunset, Mercury (m = 1.9) is less than 5° in altitude in the west-northwest. Good-bye, Mercury! It moves toward its inferior conjunction and morning appearance next month with the moon and four other naked eye planets. Saturn rises at nearly 10:40 p.m. CDT. As midnight approaches it is about 10° up in the southeast, to the lower left of Jupiter.

At the beginning of morning twilight at midmonth, bright Jupiter and Saturn are at the meridian. The Teapot of Sagittarius is to the lower right of the planets. Antares is near the horizon in the southwest. Looking along the western horizon, Arcturus is low in the west, and the Big Dipper is low in the northwest. Back at the meridian, the Summer Triangle is high in the south. Vega and Altair are west of the meridian, while that imaginary line cuts through Cygnus. Deneb is east, while Alberio is west of the meridian. The body of the Swan – from Deneb to Alberio – points toward the southwest. Farther east, Fomalhaut is low in the southeast, while brightening Mars is higher in the east-southeast. On June 15th, the crescent moon is low in the east. Farther northward along the horizon, Capella peaks above the north-northeast horizon, with Perseus and Cassiopeia standing above it. With the solstice nearing, daylight has increased about 10 minutes since June 1. Together daylight and twilight span over 19.5 hours. In the evening after twilight ends, Arcturus and Spica, west of the meridian, gleam from the south-southwest. Golden-orange Arcturus is high in the sky. The trapezium shape of Corvus is tilted toward the southwest horizon, to the lower right of Spica. Leo, with Regulus, is tilted toward the western horizon. The Big Dipper is high in the northwest above the Lion. East of the meridian, Antares is about an hour away from its high point. The classic pincers of the arachnid – Zubenelgenubi and Zubeneschamali – are west of the meridian. The Summer Triangle reigns in the east. Try to locate it as the sky darkens – before the end of evening twilight – on solstice evening. It’s lower in the sky, but the large reach of the three stars, with their individual constellations, dominates the eastern sky. Farther northward along the horizon, Cassiopeia is east of the north cardinal point and low in the sky. If you have a good view toward the northwest, you may still catch Capella, Castor, and Pollux, although they are quite low.

As for the planets, four naked eye planets are now in the morning sky. The Bright Outer Planets – Jupiter, Mars, and Saturn – are scattered across the southern sky. Mars and Jupiter are separated by nearly 57° of ecliptic longitude. Brilliant Venus pops into the morning sky during the second half of the month. The moon joins Venus on June 19 for a close grouping. Mercury joins them next month.

  • June 16: One hour before sunrise, the crescent moon (25.0d, 22%), 16.0° up in the east, is 3.8° above Alpha Piscium (α Psc, m = 3.8). Mars (m = −0.3) is over 31° up in the southeast, among faint stars in eastern Aquarius. Farther west along the ecliptic, Jupiter is nearly 25° up in the south-southwest, 5.3° to the lower right of Saturn. In the starfield, Jupiter is 1.7° to the lower left of 56 Sgr. Thirty minutes before sunrise, Venus is over 4° up in the east-northeast.
  • June 17: One hour before sunrise, Jupiter is nearly 25° up in the south-southwest. It is 5.3° to the lower right of Saturn. In the starfield, Jupiter is 1.6° to the lower left of 56 Sgr. Mars is 31° up in the southeast. Farther to the north along the horizon, the moon (25.8d, 14%), about 11° up in the east, is in southern Aries. The lunar crescent is over 15° below Hamal (α Ari, m = 2.0). Note that the Pleiades are at about the same altitude as the moon, nearly 20° to the left of the moon’s crescent. Thirty minutes before sunrise, Venus (m = −4.4) is nearly 5° in altitude in the east-northeast, 24° to the lower left of the lunar crescent. Saturn rises at 10:30 p.m. CDT, about 120 minutes after sunset.
  • June 18: One hour before sunrise, bright Jupiter is over 24° in altitude in the southwest, and 5.4° to the lower right of Saturn. Use a binocular to observe that Jupiter is 1.6° to the lower left of 56 Sgr. Farther east, Mars is nearly 32° up in the southeast. Notice that Mars is about 20° to the upper right of Beta Ceti (β Cet, m = 2.0). Notice that Mars, β Cet, and Fomalhaut – over 26° to β Cet’s right – make a large triangle in the southeast. Not many bright stars are found in this region, making the figure easy to locate. The crescent moon (26.8d, 8%), over 6° up in the east-northeast, is over 9° to the lower right of the Pleiades (M45). Thirty minutes before sunrise, Venus is nearly 6° in altitude in the east-northeast. Venus is nearly 12° to the lower left of the moon. You may need a binocular to see the moon in the growing twilight as sunrise approaches.
Venus and the moon, June 19, 2020
2020, June 19: Before sunrise the old moon is 1.0° to the lower left of brilliant Venus.
  • June 19: One hour before sunrise, Jupiter is nearly 24° up in the south-southwest. It is 5.4° to the lower right of Saturn. The planets continue to retrograde. Note their slow movement relative to the starry background. Saturn is 2.2° to the lower right of σ Cap while Jupiter inches past 56 Sgr. This morning the gap is 1.6°. Jupiter is to the lower left of the dimmer star. Farther east along the ecliptic, Mars is over 32° up in the southeast. Forty-five minutes before sunrise, the old moon (27.8d, 4%), about 4° up in the east-northeast, is 1.0° to the lower left of Venus (m = −4.4). Find a clear horizon to view the pair. This is the closest grouping of the moon and Venus during this Venusian apparition! Through a telescope, Venus is only 8% illuminated but a large 51” across. Betelgeuse (α Ori, m = 0.4) is at its solar conjunction. While it is about 15° south of the ecliptic, it crosses the meridian with the sun.
Venus moves through Taurus, June and July 2020
2020, June 20: Venus is in Taurus and begins to move toward Aldebaran and the Hyades. Use optical assistance to locate the star during growing twilight.
  • June 20: One hour before sunrise, look for Jupiter, 23° up in the south-southwest. It passes 1.6° to the lower left of 56 Sagittarii. Saturn is 5.5° to the upper left of Jupiter. Farther east, Mars is nearly 33° up in the southeast. As measured along the ecliptic, the Jupiter – Mars gap is over 60°. Begin looking for Venus (m = −4.5), low in the east-northeast at this time interval. By 45 minutes before sunrise, the brilliant planet is nearly 5° in altitude. During the next few mornings begin looking for Aldebaran (α Tau, m = 0.8) with binoculars. The summer solstice occurs at 4:44 p.m. CDT. Daylight has stretched 11 minutes since June 1st.
  • June 21: The moon reaches its New phase at 1:41 a.m. CDT. An annular solar eclipse tracks across Africa, the Arabian Peninsula, South Asia, and the western Pacific Ocean. Venus rises at Nautical Twilight, when the sun is 12° below the horizon. One hour before sunrise, bright Jupiter is over 23° up in the south-southwest, 5.5° to the lower right of Saturn. In the starfield Jupiter is 1.6° to the lower left of 56 Sgr, while Saturn is 2.3° to the lower right of σ Cap. Forty-five minutes before sunrise, Venus is about 4° up in the east-northeast.
  • June 22: One hour before sunrise, Jupiter is about 23° up in the south-southwest. Saturn is 5.6° to the upper left of Jupiter. In the starfield, Jupiter is 1.6° to the lower left of 56 Sgr. Farther east along the ecliptic, Mars – in the sparsely populated area of eastern Aquarius – is nearly 34° up in the southeast. Forty-five minutes before sunrise, brilliant Venus is nearly 6° up in the east-northeast. Have you observed it yet? In the evening – one hour after sunset – the moon (1.8d, 4%) is nearly 5° up in the west-northwest and 5.2° to the lower left of Pollux (β Gem, m = 1.2).
  • June 23: One hour before sunrise, Jupiter is 23.0° up in the south-southwest. It is 5.6° to the lower right of Saturn and 1.7° to the lower left of 56 Sgr. Farther east on the ecliptic, Mars is 34.0° up in the southeast. During the next few mornings watch it pass dimmer stars in Pisces as it moves into that constellation. This morning Mars is 1.4° to the upper right of 27 Piscium (27 Psc, m = 4.9). Use a binocular to see the starfield. Capella (α Aur, m = 0.1) is less than 15° up in the northeast. Forty-five minutes before sunrise, Venus (m = −4.6) is nearly 7° up in the east-northeast. One hour after sunset, the crescent moon (2.8d, 9%) – over 12° in altitude in the west-northwest – is over 14° to the upper left of Pollux. With a binocular note that the lunar crescent is 1.4° to the upper right of the Beehive Cluster (M44, NGC 2632). At this time of the year, the twilight is quite bright at this time interval after sunset. Nautical Twilight does not occur until 78 minutes after sunset. Follow the moon as the early evening progresses. Can you find the Beehive? The bright stars in the northwest – Pollux, Castor (α Gem, m = 1.6), and Capella are making their last stands in the evening sky.
  • June 24: One hour before sunrise, Jupiter – 22.0° up in the south-southwest – is 5.7° to the lower right of Saturn as both planets retrograde. Jupiter appears to move westward faster than Saturn. In the starfield, Jupiter is 1.7° below 56 Sgr. Farther east, Mars is nearly 35° up in the southeast. It is 0.7° to the right of 27 Psc. Forty-five minutes before sunrise, Venus is over 7° up in the east-northeast. One hour after sunset, the moon (3.8d, 16%) – over 20° up in the west – is 9.2° to the lower right of Regulus (α Leo, m = 1.3).
  • June 25: One hour before sunrise, Jupiter, over 21° up in the south-southwest, is 5.7° to the lower right of Saturn (m = 0.2). In the starfield, Jupiter is 1.7° below 56 Sgr, while Saturn is 2.6° to the lower right of σ Cap. Farther east, Mars has moved into Pisces, 0.2° to the upper right of 27 Psc. Jupiter and Mars are separated by nearly 64° of ecliptic longitude. Forty-five minutes before sunrise, Venus is nearly 8° up in the east-northeast. Through a telescope, the brilliant planet is in its morning crescent phase, 13.5% illuminated and 47” across. One hour after sunset, the moon (4.8d, 25%) is 6.1° to the upper left of Regulus in the western sky.
  • June 26: One hour before sunrise, Mars – nearly 36° in altitude in the southeast – is between 27 Psc and 29 Piscium (29 Psc, m = 5.1). While not midway between them, Mars is above a line that connects the stars. It is 0.4° to the upper left of 27 Psc and 0.5° to the right of 29 Psc. Use a binocular to see Mars with the starfield. Farther west along the ecliptic, bright Jupiter – about 21° up in the south-southwest – is 5.8° to the lower right of Saturn and 1.8° below 56 Sgr. Forty-five minutes before sunrise, Venus is about 8° up in the east-northeast. This brilliant planet is 9.2° below Alcyone (η Tau, m = 2.8), the brightest star in the Pleiades star cluster. A binocular helps you see the star cluster. One hour after sunset, the moon (5.8d, 36%), over 30° up in the west-southwest, is 8.2° below Denebola (β Leo, m = 2.1).
Four bright planets in the morning sky
2020, June 27: Four bright morning planets span 131° of ecliptic longitude, from Venus in the east-northeast to Jupiter in the southwest.
  • June 27: One hour before sunrise, brilliant Venus, nearly 7° up in the east-northeast, is 9.3° below M45. The planet is 4.9° to the upper right of Aldebaran. At this time interval, the star is very low in the sky. What is the first date you see Aldebaran without optical aid? Look for it with a binocular as it rises higher in the sky as twilight brightens. Farther westward along the ecliptic, Mars is nearly 36° up in the southeast. It is 0.1° to the lower left of 29 Psc. Jupiter is nearly 21° up in the south-southwest, 5.8° to the lower right of Saturn. In the starfield, Jupiter is 1.8° below 56 Sgr. In the evening, one hour after sunset, the moon (6.8d, 47%), over 36° in altitude in the southwest, is 3.5° to the upper right of Eta Virginis (η Vir, m = 3.9) Jupiter rises at 9:30 p.m. CDT, about one hour after sunset. An hour later, Jupiter is nearly 9° up in the southeast with Saturn to its lower left.
  • June 28: The moon reaches its First Quarter phase at 3:16 a.m. CDT. Sixty minutes before sunrise, Venus is over 7° up in the east-northeast. It is 4.8° to the upper right of Aldebaran. Use a binocular to see the star as it rises higher in the sky later during twilight. Mars (m = −0.5) is over 36° up in the southeast, 0.7° to the lower left of 29 Psc. Jupiter is about 20° up in the south-southwest. Saturn is 5.9° to its upper left. In the starfield, Jupiter is 1.9° below 56 Sgr. One hour after sunset, the moon (7.8d, 59%), over 38° up in the southwest, is 8.8° to the upper right of Spica.
  • June 29: One hour before sunrise, Jupiter is over 20° up in the south-southwest and 5.9° to the lower right of Saturn and 1.9° below 56 Sgr. Farther east, Mars is nearly 37° up in the southeast, 1.3° to the lower left of 29 Psc. Brilliant Venus (m = −4.7) is nearly 8° up in the east-northeast, 4.6° to the upper right of Aldebaran. During the next 18 mornings, Venus displays its greatest visual brightness. While the photometric brightness increases, your eye likely does not see any difference in the visual intensity of the planet.  The moon is at perigee at 9:13 p.m. CDT, 229,260 miles away. One hour after sunset, the moon (8.8d, 70%) is over 37° in altitude in the south-southwest, 9.9° to the upper left of Spica. As midnight approaches, Jupiter is over 19° up in the south-southeast. Jupiter passes 0.6° to the upper left of Pluto (m = 14.3). At this hour, Jupiter is 5.9° to the upper right of Saturn as the planetary trio (Jupiter, Saturn, and Pluto) retrogrades.
The moon in the Scorpion's pincers, June 30, 2020
2020, June 30: Moon in the classic Scorpion’s pincers. Use a binocular or block the moon to see the dimmer stars.
  • June 30: Mars rises a few minutes before 12:30 a.m. CDT. One hour before sunrise, brilliant Venus is over 8° up in the east-northeast. It is 9.8° below the Pleiades. While Aldebaran is lower in the sky at this time interval, Venus is 4.4° to the upper right of the star. Look with a binocular as twilight progresses and the star is higher in the sky. Through a telescope, Venus is 18% illuminated – a morning crescent – that is 43” across. Farther west along the ecliptic, Mars is over 38° in altitude in the southeast. It is 1.8° to the lower left of 29 Psc. Use a binocular to see the planet in the starfield. Jupiter is over 19° in altitude in the southwest, 6.0° to the lower right of Saturn. In the starfield, Jupiter is 2.0° below 56 Sgr while Saturn is 2.9° to the lower right of σ Cap. As measured along the ecliptic, Venus is nearly 132° away from Jupiter and 64.0° from Mars in ecliptic longitude. One hour after sunset, the moon (9.8d, 80%), 34° up in the south is between the Scorpions classic pincers Zubenelgenubi (α Lib, m = 2.8) and Zubeneschamali (β Lib, m =2.6). The gibbous shape is 2.7° to the upper left of the southern pincer and 6.4° to the lower right of the northern pincer. The moon is at perigee at 9:13 p.m. CDT, 229,260 miles away. Mercury is at inferior conjunction at 9:53 p.m. CDT and moves toward the morning sky.

At the end of the month when morning twilight begins, the bright outer planet duo – Jupiter and Saturn – is west of the meridian. Brightening Mars, the third planet visible at this hour, is in the east-southeast. Higher in the south, the Summer Triangle is west of the meridian. At this hour, Arcturus is low in the west-northwest. Find a spot with a clear horizon to see it. The Big Dipper is low in the north-northwest. Moving eastward along the horizon is Capella, low in the north-northeast. The Pleiades, low in the east-northeast, appears at about the same altitude as Capella. Daylight has lost only two minutes in the 10 days since the solstice. At the end of evening twilight, red-orange Antares is slightly east of the meridian, less than one-third of the way up in the sky. The bright gibbous moon seems to be captured in the classic pincers of Scorpius. It is a few degrees above Zubenelgenubi. You may need a binocular or shield your eyes from the moon’s brightness to see the dimmer pincer stars. Farther east, Jupiter and Saturn are low in the southeastern sky. Golden-orange Arcturus appears high in the southwest while sapphire-white Vega is high in the east. Draw a line from Arcturus to Vega. About two-thirds of the way from the former to the latter is the Keystone of Hercules. The globular cluster M13 is found on the west side of this shape. Arcturus is high above Spica. Farther west, Leo is near the horizon. The Big Dipper is higher in the northwest, above the Lion. Back in the eastern sky, the Summer Triangle is about halfway up in the sky. Summer is here!

Astronomy, Feature, Sky Watching

2020-2021: Brilliant Planet Venus as a Morning Star
Morning Star Venus and the Crescent Moon, January 29, 2014
2014, January 29: Brilliant Morning Star Venus appears with the crescent moon. The moon is 7.2° to the lower left of Venus.

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.

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 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.

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.

Astronomy, Feature, Sky Watching

2020, October 13: Mars at Opposition
Mars
The Red Planet from the Mars Global Surveyor shows the effects of a global dust storm (NASA)

Mars at opposition, October 13, 2020

by Jeffrey L. Hunt

Mars reaches opposition on October 13, 2020, among the dim stars of southeastern Pisces. At opposition, Mars is biggest and brightest. Unlike some Internet memes, it is not as big as the moon. It shines as a bright star in the sky all night long.

Mars has captured our attention. It’s reddish appearance in the sky has cast it as a warrior in several cultures. After the inventions of larger telescopes, Mars brought the attention of many observers. Public announcements of possible civilizations there likely spurred the growth of science fiction writing and storytelling.

While Mars is close to Earth, it appears small even through a telescope. Through a telescope’s eyepiece, it appears as a red-ochre globe. A polar cap and some darker equatorial markings might be visible. At times, Mars surface cannot be seen when dust storms engulf the planet. For those with a telescope, Sky & Telescope’s Mars profiler shows what is visible on the surface on any date and time.

Mars Retrograde 2020
This chart shows the apparent motion of Mars compared to the starry background, during a 168-day interval that includes the planet’s opposition.

The Mars opposition occurs at the end of a span of 91 days, with the three Bright Outer Planets (Jupiter, Saturn, and Mars) passing their oppositions. Jupiter and Saturn are at their oppositions during a span of 6 days in July 2020.

Mars’ opposition occurs 72 days after it passes its orbital point closest to the sun (August 2, 2020), known as a planet’s perihelion, while the previous opposition occurred 49 days before perihelion (September 15, 2018). The July 27, 2018, event was called a “perihelic” opposition.

 

Mars and Earth in their orbits near the opposition of Mars 2020
This chart views the motions of Earth and Mars from north of the ecliptic during the same time interval as the retrograde chart above.

 

The accompanying charts show two perspectives of the planet’s motion from July 21, 2020, to January 5, 2021. The first chart shows the apparent motions of Mars as seen against the starry background in southeastern Pisces. The second chart shows the view of a section of Earth’s orbital path and Mars’ orbit as viewed from above the solar system.

Celestial Brightness

In the notes in this article, the “m” numbers are measures of the planets’ and stars’ brightness. The lower the number, the brighter the celestial object. The sun has the lowest value (−26.5) on this scale. Afterall it is so bright it creates daytime on our planet and shines on the moon and other planets in its system. The planets’ brightness changes as their distances from Earth vary.

Each full digit numeric change on the magnitude scale equals a change of 2.5 times (2.512x). From the beginning of the sequence to its brightest, Mars brightness increases 25 times, a dramatic, but easily observed change of brightness. As we move away from Mars in start the new year, the planet’s brightness decreases about ten times from its brightest light. So, like an excellent golf score, the lower the number the brighter the “star.”

All Planets in Morning Sky

As the sequence opens, five naked eye planets are in the morning sky, along with Uranus, Neptune, and Pluto. At about 40 minutes before sunrise, the bright planets span nearly 168° of ecliptic longitude, stretching from horizon to horizon. Mercury (m = 0.4), a day before its greatest elongation, is quite low in the east-northeast. Use a binocular and find a clear horizon. Brilliant Venus (m = −4.6) is about 20° up in the east, to the lower left of Aldebaran. Mars (m = −0.9) is over 45° up in the south-southeast. Farther westward along the ecliptic, Saturn (m = 0.1) is about 10° up in the southwest. Bright Jupiter is 6.4° to Saturn’s lower right. Because Mercury is low in the sky, start looking for Jupiter about an hour before sunrise. Work your way eastward across the sky to find Mercury with a binocular 10-20 minutes later. I’ve seen Jupiter just a few degrees above the horizon without optical assistance. It might be possible to see all of them in the sky together.

Mars at Opposition

Here’s what to look for:

  • July 21, 2020: This is the first day displayed on the charts. See the text above for a description of the menagerie of morning planets. Bright Mars (m = −0.9) is moving eastward against the starry background. As midnight approaches, the Red Planet is 5° up in the east.
  • August 2: Mars (m = −1.1) is at perihelion, 1.38 AU from the sun, its closest point to the sun in its orbit. As midnight approaches, it is 10° up in the east.
  • August 4: Mars (m = −1.2) passes 0.4° to the upper left of a star with the catalog name 89 Piscium (89 Psc, m = 5.1). The star is dim. Use a binocular to see Mars with the starfield.
Mars and Moon, August 8, 2020
As midnight approaches the moon is 2.0° to the lower right of Mars that is about 13° in altitude in the east.
  • August 8: As midnight approaches the moon (19.5 days past the New phase, 73% illuminated) is 2.0° to the lower right of Mars (m = −1.3) that is about 13° in altitude in the east.
  • August 22: Mars (m = −1.6) passes 0.5° to the upper left of Nu Piscium (ν Psc, m = 4.4). Four hours after sunset, Mars is nearly 18° in altitude in the east.
  • September 5: Four hours after sunset, the moon (18.1d, 86%) – over 20° up in the east – is 0.7° below Mars (m = −1.9).
  • September 9: Mars (m = −2.0) begins to retrograde; four hours after sunset, it is nearly 25° up in the east-southeast. See the first chart above Retrograde motion is an illusion. To early astronomers, this was the cosmological problem of the time. Those who thought Earth was at the center of all motion used a series of circles needed to get the planets to move westward compared to the starry background. For observers who thought all the planets revolved around the sun, Mars seems to move backwards when our faster moving planet catches, overtakes, and moves past the Red Planet. Mars and all objects in the solar system beyond it seem to back up for a period of time, then resume their eastward motion compared to the starry background as we move past. This is more obvious for the bright planets, especially Mars. The issue of Earth’s place in the solar system was not finalized until after the invention of the telescope and precision instruments were developed to measure our planet’s revolution around the sun.

For those with further interest, the variable star Mira (ο Cet) is predicted to reach its brightness. This paragraph describes more Mira’s brightness prediction and its location to Mars Predicted dates for the brightest phase range from mid-September to late in the month. The brightest magnitude is uncertain, ranging from 2.0 to 4.0. On September 15, Mira is about 12° to the lower left of Mars. For the latest observations of Mira’s brightness, check with the American Association of Variable Star Observers (https://www.aavso.org/).

Mars and Moon, October 2, 2020
Three hours after sunset, Mars is 24° up in the east-southeast. The bright gibbous moon is 1.3° to the lower right of the planet.
  • October 2: Three hours after sunset, Mars (m = −2.5) is 24° up in the east-southeast. The bright gibbous moon (15.7d, 98%) is 1.3° to the lower right of the planet.
  • October 6: Earth and Mars (m = −2.6) are at their closest. The planet passes 0.4° to the lower right of Mu Piscium (μ Psc, m = 4.8). Use a binocular to see the dimmer star with Mars. Three hours after sunset, the Red Planet is over 25° in altitude in the east-southeast.
  • October 13: Earth is between Mars and the sun. When the sun sets, Mars is rising in the eastern sky. Around midnight (about 1 a.m. during Daylight Saving Time), Mars is in the south. Mars sets in the western sky at sunrise. Mars and sun are opposite in the sky. Mars is at opposition, 1.43 AU from the sun and 0.419 AU from Earth. Three hours after sunset, the planet is over 30° up in the east-southeast.
  • October 23: Mars (m = −2.4) passes 0.6° to the lower right of 80 Piscium (80 Psc, m = 5.5). Use a binocular to see the star with Mars. Two hours after sunset, Mars is over 25° in altitude in the east-southeast.
Mars and the moon, October 29, 2020
Two hours after sunset, the bright moon is nearly 26° up in the east-southeast. Mars is 4.8° to the upper right of the gibbous moon.
  • October 29: Two hours after sunset, the bright moon (13.2d, 98%) is nearly 26° up in the east-southeast. Mars (m = −2.2) is 4.8° to the upper right of the gibbous moon.
  • November 13: Mars’ (m = −1.7) retrograde ends. Mars begins to move eastward compared to the starry background. Two hours after sunset, the planet is nearly 40° up in the southeast.
Mars and the moon, November 25, 2020
At the end of evening twilight, Mars is over 40° in altitude in the southeast. The moon is 5.1° to the lower left of Mars.
  • November 25: At the end of evening twilight, Mars (m = −1.3) is over 40° in altitude in the southeast. The moon (10.8d, 84%) is 5.1° to the lower left of Mars. (The end of twilight occurs about 100 minutes after sunset.)
  • December 4: Mars (m = −1.0) passes 1.0° below Epsilon Piscium (ε Psc, m = 4.2). Use a binocular to track Mars compared to the dimmer starry background. At the end of evening twilight, Mars is over 45° in altitude in the southeast.
  • December 12: Mars (m = −0.7) passes 0.6° above Zeta Piscium (ζ Psc, m = 5.2). Another dim star. You’ll likely need a binocular to see the star. At the end of evening twilight, find the Red Planet 50° up in the southeast.
  • December 21: Forty-five minutes after sunset, Mars (m = −0.5) is nearly 48° up in the southeast. The half-full moon (7.3d, 50%), over 40° up in the south-southeast, is about 24° to the lower right of Mars. This is the evening of the once-every-generation Great Conjunction of Jupiter (m = −2.0) and Saturn (m = 0.6). The conjunction is about 14° in altitude above the southwest horizon. Mar and Jupiter are nearly 83° apart.
Mars and the moon, December 23, 2020
At the end of evening twilight, Mars is 55° up in the south-southeast. The moon is 5.6° to the lower left of Mars.
  • December 23: At the end of evening twilight, Mars is 55° up in the south-southeast. The moon (9.3d, 69%) is 5.6° to the lower left of Mars.
  • December 31: Mars (m = −0.2) passes 1.0° to the lower left of Pi Piscium (π Psc, m = 5.5). A binocular is needed to see the dim star and the planet together. At the end of evening twilight, Mars is nearly 60° in altitude in the south-southeast.
  • January 5, 2021: This is the last day displayed on the charts. At the end of evening twilight, Mars (m = −0.1) is 60° in altitude in the south-southeast.

The sequence ends with Jupiter and Saturn approaching their solar conjunctions. The giant planetary pair is 15 days past the December 21, 2020, Great conjunction. Jupiter is 1.7° east of Saturn. During mid-twilight, Jupiter is about 6° up in the southwest. Along with Mercury, Jupiter and Saturn are less than 20° east of the sun. Mars is over 85° of ecliptic longitude from Jupiter. In the morning sky, Venus is about 5° up in the southeast during morning twilight. While the sun is between them, Venus is over 37° in ecliptic longitude from Jupiter.

What’s Next for Mars

Mars heads toward brighter starfields during 2021. During March, it passes the Pleiades and the Hyades, and moves between the Bull’s horns in mid-April. Mars strolls through the Beehive Cluster in late June, although the pair is low in the west-northwest during evening twilight. During mid-July, Venus passes Mars in the western evening sky. Later in the month, Mars passes Regulus with Venus higher in the sky, although the Mars – Regulus pair is very low in the sky during mid-twilight. Then, Mars makes a slow slide into evening twilight. It reaches its solar conjunction on October 7, 2021. The next opposition is December 7, 2022. Mars is farther away, 0.549 AU. This is followed by the January 15, 2025, opposition, when the Martian distance increases to 0.734 AU.

Astronomy, Feature, Sky Watching

1623: The Great Conjunction of Jupiter and Saturn

The Starry Sky
(NASA Photo)

The 2020 Great Conjunction of Jupiter and Saturn is the closest conjunction of these giant planets since the conjunction of them in 1623.

by Jeffrey L. Hunt

Was this conjunction observed?

The Jupiter – Saturn conjunction of 1623 occurred in the wake of the invention of the telescope, so observing was in its infancy; yet, the sky was full of planetary activity. A partial lunar eclipse (April 15, 1623) was visible throughout the Americas and in Central Europe, where the moon was setting as the eclipse reached its 90% magnitude. Venus passed Jupiter and Saturn in late June and Mercury passed the planetary pair less than two weeks later, when the planets were about 22° east of the sun. With the inner planets in the vicinity of the impending Great Conjunction and Mars reaching opposition (July 4, 1623), surely sky watchers were observing the planets’ locations to test and revise their planetary motion equations.

By the time of the Great Conjunction on July 16, 1623, the planetary pair was less than 13° east of the sun. By Civil Twilight, the pair was near the horizon at mid-latitudes. Without optical help, the conjunction likely went unobserved, even for those with recently minted telescopes. Even then, the observer needed some luck to find the conjunction.

In later years, two British publications stated that the 1623 conjunction was not observed. In 1886, the Monthly Notices of the Royal Astronomical Society state that the February 8, 1683, Jupiter – Saturn conjunction was the first observed “since the invention of the telescope” and that the 1623 passing went unobserved. The same statement was written in the Journal of the British Astronomical Association in 1897. Perhaps the conjunction was observed without optical aid and recorded from more southerly latitudes, when the planets were higher in the sky.

Did the two British publications make the statements out of parochialism, rather than from factual observations made around Europe regarding the first Great Conjunction observed with a telescope, or was this the first time that the conjunction fit into an eyepiece since the telescope’s invention? The February 24, 1643, conjunction was visible in the western sky during mid-twilight as well as the October 16, 1663, conjunction. At the second conjunction the planets were about 10° up in the southwest at one hour after sunset. However, at both conjunctions, the planets were nearly 1° apart. At the 1683 conjunction, the planets were close, about 0.2° apart, twice the separation of the upcoming event. While the two previous conjunctions were visible to the naked eye and individually in a telescopic eyepiece, the 1683 conjunction was the first observed with both planets simultaneously in an eyepiece. With a separation of 0.1°, the 1623 conjunction would have fit into telescopes eyepieces of that generation, but certainly those early telescopes were unwieldy to steer and hold steady, and the telescope operator needed some persistence during the days preceding the conjunction to follow the converging planets into bright twilight while they had sufficient altitude to observe them. So, while the British publications are accurate about viewing the planets simultaneously through a telescope, the two preceding conjunctions were visible to the unaided eye and individually through a telescope, and this does not speak to the issue as whether the 1623 conjunction when unobserved across all of humanity.

In recent times, Great Conjunctions occurred February 18, 1961; followed by a triple conjunction of the two planets in 1980-81; and the last occurred May 30, 2000, although this was difficult to observe.

Read the Great Conjunction of 2020 Article.

Astronomy, Feature, Sky Watching

2020: The Evening Sky

2020 Setting Sky in west

by Jeffrey L. Hunt

This chart shows the summary of the setting of the naked-eye planets, moon, and bright stars near the ecliptic, the plane of the solar system, for 2020. The chart shows the setting of these celestial bodies compared to sunset for time intervals up to five hours after the sun’s disappearance. The three phases of twilight are displayed as well. On this chart, activity occurs in the western sky, except for the rising curves (circles) of Jupiter, Saturn and Mars. When they rise in the east at sunset, they are at opposition.

As 2020 opens, Venus is the bright Evening Star, appearing in the southwest. Mercury makes its best evening appearance, setting at the end of evening twilight during early February. Mercury’s June elongation is larger, but it sets several minutes before the end of twilight, making it difficult to observe in the brighter sky. After Venus moves past the Pleiades and Aldebaran, it moves toward Elnath (β Tauri), and then plunges toward its inferior conjunction. Jupiter and Saturn pass opposition during July. After Venus disappears from the evening sky, the slow procession of bright stars – Pollux, Regulus, Spica, and Antares – disappears into evening twilight. Jupiter and Saturn appear on the setting chart in late October, just after Mars reaches opposition. The moon has two interesting appearances with the planetary duo on November 19, 2020 and just days before the Jupiter- Saturn Great Conjunction on December 21, 2020.

The chart is calculated from data by the U.S. Naval Observatory, for Chicago, Illinois.

Key to symbols: White square, conjunction; yellow triangle, greatest elongation (GE); yellow diamond, greatest brightness (GB).

 

Astronomy, Feature, Sky Watching

2020: The Morning Sky

2020 Rising Chart

by Jeffrey L. Hunt

This chart shows the summary of the rising of the naked-eye planets, moon, and bright stars near the ecliptic, the plane of the solar system, for 2020. The chart shows the rising of these celestial bodies compared to sunrise for time intervals up to five hours before the sun’s appearance. The three phases of twilight are displayed as well. On this chart, activity occurs in the eastern sky, except for the setting curves (circles) of Jupiter, Saturn and Mars. When they set in the west at sunrise, they are at opposition.

Early in the year, the morning sky offers the three Bright Outer Planets – Jupiter, Saturn, and Mars – in the eastern predawn sky. As Mars moves eastward it passes Antares, Jupiter and Saturn. On several mornings, the moon passes the planetary trio. The highlight occurs on the morning of February 18 as the moon occults Mars as sunrise approaches in the Central U.S. Venus enters the morning sky at mid-year. The appearance of a lunar crescent with the brilliant planet is a beautiful sight. The moon appears with Mercury as the planet enters the morning sky in late July. On the morning of July 19, the moon and the five naked eye planets are in the sky. As the moon moves toward its evening appearance, Mercury appears higher in the sky, making it a little easier to see. Venus reaches its period of greatest brightness; the mid-brightness date is marked by the yellow diamond. Venus moves past Aldebaran, Pollux, Regulus, and Spica as it moves towards its superior conjunction in early 2021. Mercury’s best morning appearance occurs during November. While this is its smallest morning elongation, the angle of the ecliptic places it higher in the sky.

The chart is calculated from data by the U.S. Naval Observatory, for Chicago, Illinois.

Key to symbols: White square, conjunction; yellow triangle, greatest elongation (GE); yellow diamond, greatest brightness (GB).

Astronomy, Feature, Sky Watching

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

Jupiter, Saturn, and Mars, June 5, 2020
2020, June 5: Jupiter is 4.9° to the lower right of Saturn. Mars is over 49° to the east of Jupiter.

December 21, 2020: Jupiter passes Saturn in a close conjunction, a once-in-a-generation Great Conjunction. This Jupiter – Saturn conjunction is the closest Great Conjunction since 1623.

Read more about the June 2020 Planets

by Jeffrey L. Hunt

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.

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 catch Saturn again.  When Jupiter catches 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° when they are low in the east-southeast before sunrise.

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.

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.

Jupiter - Saturn 2020 Great Conjunction

Each night thereafter, Jupiter closes more 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 a close conjunction of Venus and Jupiter.  Notice the separation of the two planets.  At the 2020 Great Conjunction, Jupiter and Saturn are closer than this August 27, 2016 conjunction.

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.)