Astronomy 2023 highlights include two fine solar eclipses, the Sun heading towards solar maximum, a series of spectacular lunar occultations and much more.
Been out enjoying the sky in 2022? The past year saw two fine total lunar eclipses, a surprise meteor outburst from the Tau Herculids, a fine occultation of Mars by the Moon and more. Astronomy 2023 promises more of the same, plus much more. We’ve been doing this yearly roundup of things to look for in the sky now for well over a decade in one form or another, and the cosmos never disappoints. So, without further fanfare, here are the very best of the best events for astronomy 2023, coming to a sky near you:
Top events in 2023
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First, up let’s distill things down to the very ‘best of the best…’ If I had to choose a ‘top ten’ list of events for the coming year, here are our picks for astronomy 2023:
-Mars is fine early just off opposition in late 2022 into early 2023
-Comet 96P Machholz reaches perihelion on January 31st
-A rare hybrid solar eclipse
-A fine annular eclipse
-A good year for the Perseids and Geminids
-The Moon resumes occulting Antares
-Moon occults Mars and Jupiter (on separate dates) for North America
-Solar Cycle 25 ramps up
-Venus vs. Jupiter on March 1st, just 30’ apart
-A possible outburst from the Andromedid meteors in early December
2023: An Astronomical Primer
As with any year, there’s what is known… and unknown. Eclipses, Moon phases, and conjunctions are always sure to happen in a clockwork Universe… what’s less known are how intense the solar cycle or a given meteor shower will be, or when the next great ‘Comet of the Century’ will turn up. Even less certain are when we can expect the next naked eye nova (we get about a dozen per century) or when the next galactic supernovae will grace our skies. We haven’t seen such a spectacle since Kepler’s supernova in 1604, though we did see one in our nearby satellite galaxy the Large Magellanic Cloud in 1987. You could say we’re due…
Still, we can expect our host star to put on a good show in 2023 as we head towards the peak of the 11-year solar cycle in 2025. This is solar cycle Number 25 since we’ve started keeping records in 1755. Expect lots of sunspots, solar flares and prominences, and aurora.
2023 kicks off with all five naked eye planets visible at dusk in one visual sweep, a spectacle broken up once Mercury leaves the evening scene on January 5th.
Looking father afield in the solar system, 2023 is a ‘miss’ year for Jupiter’s outermost moon Callisto, the only major Galilean moon that can pass above or below Jove from our perspective. The moons move back towards edge-on in 2026, when a season of mutual transits and eclipses resume.
Saturn’s rings were also widest in 2017 from our perspective, and in 2023, narrow from 10 to 6 degrees wide and head towards edge-on once again in 2025.
In 2023, the very best dates to complete a ‘Messier Marathon’ and see all of the classic deep sky objects from the classic catalog in one night are the weekends of March 18th (primary) and March 25th (Secondary).
The white dwarf star Sirius B also reaches its maximum apparent separation 11.3” from its brilliant primary in 2023, offering a good opportunity to check the elusive companion off of your life-list.
Eclipses in 2023
Eclipses occur when the Moon either passes between the Sun and Earth (a solar eclipse), or the Moon passes into the Earth’s shadow (a lunar eclipse). The Moon’s orbit is inclined 5 degrees relative to the ecliptic plane, assuring that 2-3 eclipse seasons occur per year.
There are four eclipses in 2023: two solar and two lunar. This is the minimum that can occur in a given year. These span two eclipse seasons, to include:
-A hybrid annular solar eclipse for southeast Asia and Indonesia on April 20th
-A penumbral lunar eclipse for Australia and East Asia on May 5th
-An annular solar eclipse for the US southwest and Central/South America on October 14th
-A 12% partial lunar eclipse for Africa, Asia and Europe on October 28th
The Sun, Moon and Seasons in 2023
In 2023, the astronomical seasons and phenomena for the Earth unfold as follows:
Earth at perihelion: January 4th at 0.98 AU distant
Northward Equinox: March 20th
Northward Solstice: June 21st
Earth at aphelion: July 6th at 1.02 AU distant
Southward Equinox: September 23rd
Southward Solstice: December21st
In 2023, the Moon orbit versus the ecliptic is ‘hilly’ as we head towards Major Lunar Standstill in March 2025. This cycle of shallow versus steep follows an 18.6-year span. Expect higher tide fluctuations, as the Full Moon rides high in the sky for northern hemisphere observers in the winter, and low to the south in the summer. This culminates with the ‘Long Night’s Moon’ nearest the December southward solstice. In 2023, this high-riding Full Moon falls on December 26th, the day after Christmas.
The May 19th New Moon is also a ‘Black Moon’ in the old timey sense of the third in an astronomical season with four, and the August 31st Full Moon is ‘blue’ in the modern definition of the second full Moon in a calendar month.
Lunar Occultations in 2023
Lunar occultations occur when the Moon passes in front of a planet or bright star. These can be especially dramatic when the Moon is waxing, and the dark limb of our natural satellite leads the way.
There are 10 occultations of naked eye planets by the Moon in 2023:
-Venus (March 24th) for SE Asia, by a 9% illuminated, waxing crescent Moon
-Venus (November 9th) for Greenland, by a -15% illuminated, waning crescent Moon
-Mars (January 3rd) for southern Africa, by a +92% illuminated, waxing gibbous Moon
–Mars (January 31st) for the southern U.S. and Mexico, by a +74% illuminated, waxing gibbous Moon
-Mars (February 28) for Iceland and northern Scandinavia, by a +59% illuminated, waxing gibbous Moon
-Mars (September 16) for northeastern South America (North America in the daytime) by a +3% illuminated, waxing crescent Moon
-Mars (October 15) for Antarctica, by a slim +1% illuminated Moon near New
-Jupiter (February 22) for the southern tip of South America, by a +10% illuminated, waxing crescent Moon
-Jupiter (March 22) for the eastern Caribbean, by a +2% illuminated, waxing crescent Moon
-Jupiter (May 17th) for North America, by a +5% illuminated, waxing crescent Moon
In the current era, the Moon can also occult four bright +1st magnitude stars (Antares, Spica, Regulus and Aldebaran). The good news is, the Moon starts a series of occultations of Antares (Alpha Scorpii) this year, and blots out the star 5 times in 2023:
-August 25th for North America by a +58% illuminated, waxing gibbous Moon
-September 21st for the western Pacific, by a +35% illuminated, waxing crescent Moon
-October 18th for the Middle East by a +15% illuminated, waxing crescent Moon
-November 14th for eastern North America by a +3% illuminated, waxing crescent Moon
-December 12th for southeast Asia (in the daytime) by a slim -1% illuminated Moon near new
This cycle runs out until one last final occultation of Antares on August 27th, 2028.
Other stars brighter than +3rd magnitude in the synodic path of the Moon in 2023 include Gamma Virginis, Alpha Librae, Sigma Scorpii and Delta Scorpii.
Best Asteroid Occultation for 2023: Rarer still is to see an asteroid pass in front of a distant bright star. Steve Preston maintains a list for the very best asteroid occultation events for the year. Our top pick for 2023 is the occultation of the naked eye star Betelgeuse by asteroid 319 Leona across southern Europe and the southern tip of Florida on December 12th.
Astronomy 2023: The Planets
The planets continue their celestial clockwork dance in 2023 as well. The very best time to observe the inner planets (Mercury and Venus) is when they’re near greatest elongation and farthest from the Sun in the dawn or dusk sky, while outer planets are best near opposition, when they rise in the east as the Sun sets in the west, dominating the sky for the entire night.
NASA’s solar observing SOHO spacecraft also spies the planetary action as planets transit the field of view of its LASCO C3 and C2 imager. Hopefully, the list of 2023 events and transits will go live here soon.
Astronomy 2023: The Inner Planets
-Mercury reaches greatest elongation 6 times in 2023:
-January 30th, 25 degrees west of the Sun at dawn
-April 11th, 19 degrees east of the Sun at dusk
-May 29th, 25 degrees west of the Sun at dawn
-August 9th, 27 degrees east of the Sun at dusk
-September 22nd, 18 degrees west of the Sun at dawn
-December 4th, 21 degrees east of the Sun at dusk
-Venus reaches greatest (dusk) elongation 45 degrees east of the Sun on June 4th, crosses solar conjunction on August 13th at 5 degrees south of the Sun, then heads back into the dawn sky and reaches greatest elongation 46 degrees west of the Sun again on October 24th.
Astronomy 2023: The Outer Planets
Opposition rollcall for planets in 2023 is as follows:
-Jupiter (November 3rd)
-Saturn (August 27th)
-Uranus (November 13th)
-Neptune (September 19th)
-Pluto (July 22nd)
Astronomy 2023: Conjunctions
Conjunctions occur when the Moon, a star or planets appear near each other in the sky from our Earthly point of view. In keeping with our ‘best-of-the-best’ doctrine,’ here are the closest (less than one degree, or two Full Moon widths apart) conjunctions for 2023:
-Best (naked eye) planet vs. planet: Venus-Saturn (January 22nd) 20’ apart, 22 degrees east of the Sun.
-Closest planet versus bright star: Mercury-Regulus (July 29th) 6’ apart, 25 degrees east of the Sun
Other close conjunctions of planets and bright stars in 2023 include:
January 22nd: Venus 18’ from Saturn (22 degrees east of the Sun).
February 15th: Venus less than 1’ (!) from Neptune (28 degrees east of the Sun)
March 1st: Venus 30’ from Jupiter (31 degrees east of the Sun)
March 2nd: Mercury 54’ from Saturn (13 degrees west of the Sun)
July 10th: Mars 36’ from Regulus (42 degrees east of the Sun)
July 29th: Mercury 6’ from Regulus (25 degrees east of the Sun)
October 29th: Mercury 18’ from Mars (6 degrees east of the Sun)
Astronomy 2023: Meteor Showers
There are about a dozen major dependable meteor showers per year, with dozens more minor ones… Of course, the Moon’s phase always plays a role, as a near-Full Moon will obscure fainter meteors. From this perspective, favorable showers in 2023 include:
-The Lyrids (April 23nd) Zenithal Hourly Rate (ZHR) ~18 (variable up to 90) with the Moon a +16% illuminated, waxing crescent.
-The Perseids (August 13th) ZHR ~100 with the Moon a -16% illuminated, waning crescent.
-The Taurids (October 10th) ZHR ~5-15 with the Moon a -15% illuminated, waning crescent. Note that 2023 is also a perihelion year for source comet 2/P Encke.
-The Orionids (October 22nd) ZHR ~20, with the Moon a +56% illuminated, waxing gibbous.
-The Leonids (November 18th) ZHR 10-15, with the Moon a +31% illuminated, waxing crescent.
-The Geminids (December 14th) ZHR 150, with the Moon a +4% illuminated, waxing crescent.
-Could an Andromedid meteor outburst be on tap for early December 2023? This normally defunct shower was the source of several great meteor outbursts in the 19th century. Fast-forward to the early 21st century, and this shower seems to be making a comeback. Astronomers predict that 2023 may be a storm year for the enigmatic Andromedids. Also, Earth ‘may’ encounter a debris stream from periodic comet 46P/Wirtanen around December 10th-12th radiating from two possible radiants: one in the southern constellation of Sculptor, and another in the northern constellation of Pegasus.
Astronomy 2023: Comets to Watch For
As noted previously, comets come and go. What makes our ‘is interesting’ radar when it comes to comets is an expected peak magnitude of +10 or brighter. Under this rule, a handful of interesting comets have cropped up in 2023:
-C/2022 E3 ZTF (named after the Zwicky Transient Facility) may reach +5th magnitude in early February 1st as it glides through Camelopardalis into Auriga.
-Comet C/2017 K2 PanSTARRS comes off of perihelion in December 2022, and may still shine at magnitude +8 in the southern constellation of Pavo the Peacock.
–96P Machholz 1 may top out at +2nd magnitude in February 2023. The comet reaches perihelion on January 31st. Unfortunately, the comet will also pass very close to the Sun at its brightest, and will be visible low to the dawn afterwards.
-Comet 263P/Gibbs reaches perihelion on February 2nd in the constellation Capricornus, and may reach +8 magnitude.
-Comet 237P/LINEAR reaches perihelion on May 15th in the constellation Sagittarius, and may reach +9th magnitude.
-Comet T4 (Lemmon) reaches perihelion on July 31st, in the constellation Cetus passing into Telescopium and may reach +6th magnitude.
-Comet 103P/Hartley reaches perihelion on October 12th in the constellation Gemini, and may reach +8th magnitude.
-Comet 2P/Encke reaches perihelion on October 23rd in the constellation Virgo, and may reach +6th magnitude.
-Comet 62P/Tsuchinshan reaches perihelion on December 25th in the constellation Leo, and may reach +7th magnitude.
-Finally, Comet C/2021 S3 PanSTARRS may reach +8th magnitude by year’s end going in to 2024, crossing northern Centaurus during this apparition.
And waaaay out in the outer depths of the solar system out past the orbit of planet Neptune, famous Comet 1/P Halley reaches aphelion on December 9th, 2023, at 35.14 AU distant… it’s all downhill from there, as the comet begins its plunge towards the inner solar system for perihelion in the summer of 2061. Let’s see, by then I’ll be…
And of course, we have the next Great North American Total Eclipse to look forward to on April 8th, 2024, as the shadow of the Moon sweeps across Mexico, the U.S. and the Canadian Maritimes.
Isn’t it great that we get to share the sky together in 2023? Watch this space, as we expand on these fine celestial events and more in the coming year.
-Thanks to John Flannery for weighing in on his list of the best astronomical events for 2023, and congrats on the first Irish Astronomy Week, coming right up on March 19th, 2023!