ISO 2025-W51
Week begins: Monday, December 15, 2025
Calendar
| Date | Zodiac day | Events |
|---|---|---|
| Mon, Dec 15, 2025 | ♐ 24 | Polaris (α UMi) / Polaris (α Ursae Minoris) —  Var 2 2.0 1.9–2.1 — Arctic Autumn |
| Tue, Dec 16, 2025 | ♐ 25 | |
| Wed, Dec 17, 2025 | ♐ 26 | Finest NGC 18 / NGC 1023 · Arp 135 —  10 9.6 — Northern Autumn |
| Thu, Dec 18, 2025 | ♐ 27 | M34 — 6 5.5 — Northern AutumnM77 — 9 8.9 — Tropical Autumn |
| Fri, Dec 19, 2025 | ♐ 28 | C67 / NGC 1097 — 9 9.2 — Southern Autumnβ For —  4 4.5 — Southern Autumn |
| Sat, Dec 20, 2025 | ♐ 29 | 🌑 New Moon — 01:43:21 UTC |
| Sun, Dec 21, 2025 | ♑ 1 | ♑ Sun enters Capricorn · Winter solstice · Yule — 15:03:05 UTC β Hor — 5 5.0 — Southern Winter |
Weekly Solar-System Ephemeris
Snapshot: Week begins December 15, 2025, 00:00 UTC.
(-90° to +90°; defaults +45°, 21:00 LAT)
| Body | ☉︎ | ☽︎ | ☿︎ | ♀︎ | ♂︎ | ♃︎ | ♄︎ |
|---|---|---|---|---|---|---|---|
| Ecliptic | ♐︎ 23°15′ β −0°00′ | ♎︎ 28°06′ β −3°34′ | ♐︎ 3°56′ β +1°32′ | ♐︎ 17°49′ β +0°10′ | ♐︎ 29°46′ β −0°46′ | ♋︎ 23°22′ β +0°12′ | ♓︎ 25°25′ β −2°19′ |
| Observing |  | -8.5 | ☉︎ | ☉︎ | ☉︎ | -2.6 | 1.0 |
| Rise | 07:36 | 03:03 | 05:57 | 07:11 | 08:11 | 18:33 | 12:30 |
| Set | 16:24 | 13:14 | 15:20 | 16:01 | 16:45 | 09:48 | 00:03 |
Extended targets:
| Body | ⚳︎ | ♅︎ | ♆︎ | ♇︎ |
|---|---|---|---|---|
| Ecliptic | ♈︎ 4°06′ β −10°07′ | ♉︎ 28°30′ β −0°12′ | ♓︎ 29°23′ β −1°21′ | ♒︎ 2°14′ β −3°46′ |
| Observing | 8.7 | 5.6 | 7.7 | 14.6 |
| Rise | 13:29 | 14:48 | 12:33 | 10:30 |
| Set | 00:33 | 05:42 | 00:26 | 19:12 |
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.
Planet Finder
Sky Notes
Kilroy: Sky Notes · generated 2026-10-23 21:06:30 UTC
ISO 2025-W51 runs from December 15 through December 21. Mercury is about 1.4° in ecliptic longitude from Dschubba in Scorpius. Saturn and Neptune are separated by about 4.0° in geocentric ecliptic longitude at the Monday 00:00 UTC snapshot.
Naked eye: 🌑 New Moon — 01:43:21 UTC. The dark Moon favors faint targets and extended star fields. Use Polaris as the week’s fixed-sky framework.
Planets: Moon: Naked eye; magnitude -8.5; direct motion; 21.6% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Solar conjunction in ecliptic longitude Dec 20 01:43 UTC. Conjunction with Mercury in ecliptic longitude Dec 18 10:01 UTC. Conjunction with Venus in ecliptic longitude Dec 19 16:18 UTC. Conjunction with Mars in ecliptic longitude Dec 20 12:42 UTC. Mercury: In solar glare; magnitude -0.5; direct motion; 78.9% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 18 10:01 UTC. Venus: In solar glare; magnitude -3.9; direct motion; 99.6% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 19 16:18 UTC. Mars: In solar glare; magnitude 1.2; direct motion; 99.8% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 20 12:42 UTC. Ceres: Telescope; magnitude 8.7; direct motion; 97.1% illuminated. Monday 00:00 UTC snapshot. Jupiter: Naked eye; magnitude -2.6; retrograde motion; 99.8% illuminated. Monday 00:00 UTC snapshot. Saturn: Naked eye; magnitude 1.0; direct motion; 99.7% illuminated. Monday 00:00 UTC snapshot. 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.
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.
Small telescope: Arp 135: consult its dedicated finder and observing story for equipment guidance; M34: consult its dedicated finder and observing story for equipment guidance; M77: consult its dedicated finder and observing story for equipment guidance; NGC 1097: consult its dedicated finder and observing story for equipment guidance
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 05:57; sets 15:20 (45°N, local apparent solar time). Visual magnitude -0.5. The disk is 78.9% illuminated (gibbous). It is 19.4° from the Sun, on its west side. Motion is direct at 1.331° per day in ecliptic longitude at the snapshot. Position reference: Acrab, 0.6° away. Conjunction with Moon in ecliptic longitude Dec 18 10:01 UTC. Mercury: 0.6° from Acrab in the Pathfinder.
Venus
Venus: in solar glare at the Monday 00:00 UTC snapshot. Rises 07:11; sets 16:01 (45°N, local apparent solar time). Visual magnitude -3.9. The disk is 99.6% illuminated (nearly full). It is 5.4° from the Sun, on its west side. Motion is direct at 1.259° per day in ecliptic longitude at the snapshot. Position reference: Sabik, 7.0° away. Conjunction with Moon in ecliptic longitude Dec 19 16:18 UTC. Venus: 7.0° from Sabik 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 57.1° below the horizon. Rises 03:03; sets 13:14 (45°N, local apparent solar time). Visual magnitude -8.5. The disk is 21.6% illuminated (waning crescent). It is 55.2° from the Sun, on its west side. Motion is direct at 11.889° per day in ecliptic longitude at the snapshot. Position reference: Spica, 4.2° away. Solar conjunction in ecliptic longitude Dec 20 01:43 UTC. Conjunction with Mercury in ecliptic longitude Dec 18 10:01 UTC. Conjunction with Venus in ecliptic longitude Dec 19 16:18 UTC. Conjunction with Mars in ecliptic longitude Dec 20 12:42 UTC. Moon: 4.2° from Spica in the Pathfinder.
Mars
Mars: in solar glare at the Monday 00:00 UTC snapshot. Rises 08:11; sets 16:45 (45°N, local apparent solar time). Visual magnitude 1.2. The disk is 99.8% illuminated (nearly full). It is 6.6° from the Sun, on its east side. Motion is direct at 0.754° per day in ecliptic longitude at the snapshot. Position reference: Kaus Australis, 11.7° away. Conjunction with Moon in ecliptic longitude Dec 20 12:42 UTC. Mars: 11.7° from Kaus Australis 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 23.7° above the horizon. Rises 18:33; sets 09:48 (45°N, local apparent solar time). Visual magnitude -2.6. The disk is 99.8% illuminated (nearly full). It is 149.9° from the Sun, on its west side. Motion is retrograde at 0.102° per day in ecliptic longitude at the snapshot. Position reference: Pollux, 6.5° away. Jupiter: 6.5° from Pollux 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 28.9° above the horizon. Rises 12:30; sets 00:03 (45°N, local apparent solar time). Visual magnitude 1.0. The disk is 99.7% illuminated (nearly full). It is 92.2° from the Sun, on its east side. Motion is direct at 0.030° per day in ecliptic longitude at the snapshot. Position reference: Fumalsamakah, 13.1° away. Neptune is 4.1° away at the snapshot. Saturn: 13.1° from Fumalsamakah 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 60.2° above the horizon. Rises 14:48; sets 05:42 (45°N, local apparent solar time). Visual magnitude 5.6. The disk is 100.0% illuminated (nearly full). It is 155.2° from the Sun, on its east side. Motion is retrograde at 0.037° per day in ecliptic longitude at the snapshot. Position reference: Aldebaran, 12.8° away. Uranus: 12.8° 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 32.7° above the horizon. Rises 12:33; sets 00:26 (45°N, local apparent solar time). Visual magnitude 7.7. The disk is 100.0% illuminated (nearly full). It is 96.1° from the Sun, on its east side. Motion is direct at 0.003° per day in ecliptic longitude at the snapshot. Position reference: Fumalsamakah, 14.7° away. Saturn is 4.1° away at the snapshot. Neptune: 14.7° 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 30.8° above the horizon. Rises 13:29; sets 00:33 (45°N, local apparent solar time). Visual magnitude 8.7. The disk is 97.1% illuminated (gibbous). It is 100.7° from the Sun, on its east side. Motion is direct at 0.134° per day in ecliptic longitude at the snapshot. Position reference: Diphda, 10.7° away. Ceres: 10.7° from Diphda 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 17.8° below the horizon. Rises 10:30; sets 19:12 (45°N, local apparent solar time). Visual magnitude 14.6. The disk is 100.0% illuminated (nearly full). It is 39.1° from the Sun, on its east side. Motion is direct at 0.026° per day in ecliptic longitude at the snapshot. Position reference: Dabih, 8.6° away. Pluto: 8.6° from Dabih in the Pathfinder.
Highlights
Mercury
In solar glare; magnitude -0.5; direct motion; 78.9% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 18 10:01 UTC. Mercury: 0.6° from Acrab in the Pathfinder.
Venus
In solar glare; magnitude -3.9; direct motion; 99.6% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 19 16:18 UTC. Venus: 7.0° from Sabik in the Pathfinder.
Moon
Naked eye; magnitude -8.5; direct motion; 21.6% illuminated. Below the horizon at 21:00 local apparent solar time, 45°N. Monday 00:00 UTC snapshot. Solar conjunction in ecliptic longitude Dec 20 01:43 UTC. Conjunction with Mercury in ecliptic longitude Dec 18 10:01 UTC. Conjunction with Venus in ecliptic longitude Dec 19 16:18 UTC. Conjunction with Mars in ecliptic longitude Dec 20 12:42 UTC. Moon: 4.2° from Spica in the Pathfinder.
Mars
In solar glare; magnitude 1.2; direct motion; 99.8% illuminated. Monday 00:00 UTC snapshot. Conjunction with Moon in ecliptic longitude Dec 20 12:42 UTC. Mars: 11.7° from Kaus Australis in the Pathfinder.
Jupiter
Naked eye; magnitude -2.6; retrograde motion; 99.8% illuminated. Monday 00:00 UTC snapshot. Jupiter: 6.5° from Pollux in the Pathfinder.
Saturn
Naked eye; magnitude 1.0; direct motion; 99.7% illuminated. Monday 00:00 UTC snapshot. Saturn: 13.1° from Fumalsamakah in the Pathfinder.
Uranus
Binoculars; magnitude 5.6; retrograde motion; 100.0% illuminated. Monday 00:00 UTC snapshot. Uranus: 12.8° from Aldebaran in the Pathfinder.
Neptune
Telescope; magnitude 7.7; direct motion; 100.0% illuminated. Monday 00:00 UTC snapshot. Neptune: 14.7° from Fumalsamakah in the Pathfinder.
Ceres
Telescope; magnitude 8.7; direct motion; 97.1% illuminated. Monday 00:00 UTC snapshot. Ceres: 10.7° from Diphda in the Pathfinder.
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. Pluto: 8.6° from Dabih in the Pathfinder.