Star Almanack
Alexander Ferrari Miller

ISO 2027-W51

Week begins: Monday, December 20, 2027

Notation:

Calendar

DateZodiac dayEvents
Mon, Dec 20, 2027♐ 29
🌗 Last Quarter — 09:10:55 UTC
β For — Binoculars 4 — Southern Autumn
Tue, Dec 21, 2027♐ 30
Wed, Dec 22, 2027♑ 1
♑ Sun enters Capricorn · Winter solstice · Yule — 02:42:10 UTC
β Hor — Binoculars 5 — Southern Winter
Thu, Dec 23, 2027♑ 2
Menkar (α Cet) — Naked eye 3 — Tropical Winter
Fri, Dec 24, 2027♑ 3
Algol (β Per) / Algol (β Persei) — Naked eye Var 2 — Northern Winter
Finest NGC 21 / NGC 1232 · Arp 41 — Telescope 11 — Tropical Winter
Finest NGC 10 / IC 289 · PN G138.8+02.8 — Telescope 12 — Northern Winter
Sat, Dec 25, 2027♑ 4
Dalim (α For) — Binoculars 4 — Southern Winter
C87 / NGC 1261 — Telescope 8 — Southern Winter
Sun, Dec 26, 2027♑ 5

Weekly Solar-System Ephemeris

Snapshot: Week begins December 20, 2027, 00:00 UTC.

(-90° to +90°; defaults +45°, 21:00 LAT)

Notation:
Body☉︎☽︎☿︎♀︎♂︎♃︎♄︎
Ecliptic♐︎ 27°51′
β −0°00′		♍︎ 22°54′
β −4°00′		♑︎ 2°23′
β −1°48′		♒︎ 0°16′
β −1°51′		♑︎ 18°34′
β −1°05′		♍︎ 26°39′
β +1°13′		♈︎ 21°02′
β −2°36′
ObservingNightNaked eye -10.4☉︎Naked eye -3.9Naked eye 1.2Naked eye -2.0Naked eye 0.4
Rise07:3723:3708:0809:5209:0923:4613:05
Set16:2311:3816:3118:5017:5212:1301:57

Extended targets:

Body⚳︎♅︎♆︎♇︎
Ecliptic♏︎ 2°32′
β +8°21′		♊︎ 7°08′
β −0°05′		♈︎ 3°52′
β −1°26′		♒︎ 5°38′
β −4°44′
ObservingTelescope 8.8Binoculars 5.6Telescope 7.7TelescopeTelescope 14.6
Rise02:3714:5512:2310:26
Set14:0806:0600:3019:07

β = ecliptic latitude (+ north, − south).
Rise and set are Local Apparent Time for the selected latitude.
Naked-eye observing uses the Sun’s altitude at the selected Monday observer time: Daylight (Sun ≥ −0.833°), Civil twilight (−0.833° to −6°), Nautical twilight (−6° to −12°), Astronomical twilight (−12° to −18°), and Night (below −18°).
Solar Glare identifies a body too close to the Sun when the sky-state rule does not already supersede its naked-eye classification.
The Sun’s observing status uses this same five-state sky classification.

Notation:

Planet Finder

Planet Finder — Greek / Symbols
Greek / Symbols
Planet Finder — English
English
Planet Finder — Mixed Learner
Mixed Learner

Sky Notes

Kilroy: Sky Notes · generated 2026-10-23 01:09:03 UTC

View:

ISO 2027-W51 runs from December 20 through December 26. Uranus is about 2.7° in ecliptic longitude from Aldebaran in Taurus.

Naked eye: 🌗 Last Quarter — 09:10:55 UTC. Moderate moonlight makes timing and local sky position important for faint targets. Use Menkar, Algol as the week’s fixed-sky framework.

Menkar: The Prominent Star at Cetus' Head — A detailed overview of Menkar, its celestial significance, and its place in the night sky.

Algol: The Iconic Eclipsing Binary of Perseus — A steadfast beacon in the constellation Perseus, Algol has captured astronomers' attention for centuries with its unique variability.

Planets: Moon: Naked eye; magnitude -10.4; direct motion; 54.4% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Conjunction with Ceres in ecliptic longitude Dec 22 23:36 UTC. Conjunction with Jupiter in ecliptic longitude Dec 20 06:29 UTC. Mercury: In solar glare; magnitude -1.0; direct motion; 99.2% illuminated. Monday 00:00 UTC snapshot. Venus: Naked eye; magnitude -3.9; direct motion; 84.4% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Conjunction with Pluto in ecliptic longitude Dec 24 10:55 UTC. Mars: Naked eye; magnitude 1.2; direct motion; 98.4% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Ceres: Telescope; magnitude 8.8; direct motion; 97.5% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 22 23:36 UTC. Jupiter: Naked eye; magnitude -2.0; direct motion; 99.2% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 20 06:29 UTC. Saturn: Naked eye; magnitude 0.4; retrograde motion; 99.8% illuminated. Monday 00:00 UTC snapshot. Station Dec 24 02:46 UTC: turns direct. Uranus: Binoculars; magnitude 5.6; retrograde motion; 100.0% illuminated. Monday 00:00 UTC snapshot. Neptune: Telescope; magnitude 7.7; direct motion; 100.0% illuminated. Monday 00:00 UTC snapshot. Pluto: Substantial telescope; magnitude 14.6; direct motion; 100.0% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Conjunction with Venus in ecliptic longitude Dec 24 10:55 UTC.

Binoculars: Trace Fornax’s charted figure in the finder, then identify β For at its charted position. Trace Horologium’s charted figure in the finder, then identify β Hor at its charted position. Trace Fornax’s charted figure in the finder, then identify Fornacis at its charted position.

Beta For: A Bright Beacon in the Fornax Constellation — An overview of Beta For, a notable star in the constellation Fornax, highlighting its significance and characteristics.

Beta Hor: The Bright Star of the Hor Constellation — An overview of Beta Hor, a prominent star in the southern sky, its characteristics, and significance.

Dalim in Fornax: A Bright Anchor in the Night Sky — Exploring the characteristics and significance of the star known as Dalim, situated in the constellation Fornax.

Small telescope: Arp 41: consult its dedicated finder and observing story for equipment guidance; PN G138.8+02.8: consult its dedicated finder and observing story for equipment guidance; NGC 1261: consult its dedicated finder and observing story for equipment guidance

Unveiling Arp 41: A Hidden Galaxy in Eridanus — A detailed look into Arp 41, a compelling galaxy offering insights into the universe's vast complexity.

The Enigmatic Planetary Nebula in Cassiopeia: PN G138.8+02.8 — A celestial remnant offering insights into stellar evolution and cosmic artistry.

A Glimpse into the Mysterious Globular Cluster in Horologium — An overview of a captivating and ancient stellar ensemble in the constellation Horologium, illuminating our understanding of celestial structures.

Substantial telescope: No fixed-sky Calendar object is classified as requiring a substantial telescope this week.

Other objects listed this week: None

Mercury

Mercury: in solar glare at the Monday 00:00 UTC snapshot. Rises 08:08; sets 16:31 (45°N, local apparent solar time). Visual magnitude -1.0. The disk is 99.2% illuminated (nearly full). It is 4.9° from the Sun, on its east side. Motion is direct at 1.587° per day in ecliptic longitude at the snapshot. Position reference: Kaus Australis, 9.8° away. Mercury: 9.8° from Kaus Australis in the Pathfinder.

Venus

Venus: naked eye at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 22.1° below the horizon. Rises 09:52; sets 18:50 (45°N, local apparent solar time). Visual magnitude -3.9. The disk is 84.4% illuminated (gibbous). It is 32.5° from the Sun, on its east side. Motion is direct at 1.231° per day in ecliptic longitude at the snapshot. Position reference: Dabih, 7.7° away. Conjunction with Pluto in ecliptic longitude Dec 24 10:55 UTC. Venus: 7.7° from Dabih in the Pathfinder.

Moon

Moon: naked eye at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 27.2° below the horizon. Rises 23:37; sets 11:38 (45°N, local apparent solar time). Visual magnitude -10.4. The disk is 54.4% illuminated (waning gibbous). It is 94.9° from the Sun, on its west side. Motion is direct at 14.013° per day in ecliptic longitude at the snapshot. Position reference: Zavijava, 6.6° away. Conjunction with Ceres in ecliptic longitude Dec 22 23:36 UTC. Conjunction with Jupiter in ecliptic longitude Dec 20 06:29 UTC. Moon: 6.6° from Zavijava in the Pathfinder.

Mars

Mars: naked eye at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 31.8° below the horizon. Rises 09:09; sets 17:52 (45°N, local apparent solar time). Visual magnitude 1.2. The disk is 98.4% illuminated (gibbous). It is 20.7° from the Sun, on its east side. Motion is direct at 0.775° per day in ecliptic longitude at the snapshot. Position reference: Nunki, 6.2° away. Mars: 6.2° from Nunki in the Pathfinder.

Jupiter

Jupiter: naked eye at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 27.8° below the horizon. Rises 23:46; sets 12:13 (45°N, local apparent solar time). Visual magnitude -2.0. The disk is 99.2% illuminated (nearly full). It is 91.2° from the Sun, on its west side. Motion is direct at 0.072° per day in ecliptic longitude at the snapshot. Position reference: Zavijava, 1.0° away. Conjunction with Moon in ecliptic longitude Dec 20 06:29 UTC. Jupiter: 1.0° from Zavijava in the Pathfinder.

Saturn

Saturn: naked eye at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 46.2° above the horizon. Rises 13:05; sets 01:57 (45°N, local apparent solar time). Visual magnitude 0.4. The disk is 99.8% illuminated (nearly full). It is 113.2° from the Sun, on its east side. Motion is retrograde at 0.008° per day in ecliptic longitude at the snapshot. Position reference: Alrescha, 10.8° away. Station Dec 24 02:46 UTC: turns direct. Saturn: 10.8° from Alrescha in the Pathfinder.

Uranus

Uranus: binoculars at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 59.9° above the horizon. Rises 14:55; sets 06:06 (45°N, local apparent solar time). Visual magnitude 5.6. The disk is 100.0% illuminated (nearly full). It is 159.3° from the Sun, on its east side. Motion is retrograde at 0.039° per day in ecliptic longitude at the snapshot. Position reference: Aldebaran, 6.2° away. Uranus: 6.2° from Aldebaran in the Pathfinder.

Neptune

Neptune: telescope at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 33.7° above the horizon. Rises 12:23; sets 00:30 (45°N, local apparent solar time). Visual magnitude 7.7. The disk is 100.0% illuminated (nearly full). It is 96.0° from the Sun, on its east side. Motion is direct at 0.003° per day in ecliptic longitude at the snapshot. Position reference: Fumalsamakah, 18.2° away. Neptune: 18.2° from Fumalsamakah in the Pathfinder.

Ceres

Ceres: telescope at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 48.5° below the horizon. Rises 02:37; sets 14:08 (45°N, local apparent solar time). Visual magnitude 8.8. The disk is 97.5% illuminated (gibbous). It is 55.7° from the Sun, on its west side. Motion is direct at 0.386° per day in ecliptic longitude at the snapshot. Position reference: Spica, 13.3° away. Conjunction with Moon in ecliptic longitude Dec 22 23:36 UTC. Ceres: 13.3° from Spica in the Pathfinder.

Pluto

Pluto: substantial telescope at the Monday 00:00 UTC snapshot. At 45°N and 21:00 local apparent solar time, it is 18.7° below the horizon. Rises 10:26; sets 19:07 (45°N, local apparent solar time). Visual magnitude 14.6. The disk is 100.0% illuminated (nearly full). It is 38.0° from the Sun, on its east side. Motion is direct at 0.026° per day in ecliptic longitude at the snapshot. Position reference: Dabih, 9.4° away. Conjunction with Venus in ecliptic longitude Dec 24 10:55 UTC. Pluto: 9.4° from Dabih in the Pathfinder.