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Polarissima Borealis — Galassia in Orsa Minore

NGC 3172

Galassia Discreto (30/100)

Lenticular

Magnitudine 13.6m Galaxy Orsa Minore (UMi) Visibile
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Descrizione

NGC 3172 is a faint galaxy in Ursa Minor, widely called 'Polarissima Borealis' — the closest NGC-cataloged object to the north celestial pole. It sits less than one degree from Polaris itself, a position that makes it one of the easier galaxies to find for anyone with a go-to mount (because it barely moves in the sky) but also one of the more visually unremarkable: a small, faint elliptical-like galaxy of magnitude 13.6 about 300 million light-years away. Its fame is entirely positional — observers add it to their lists more as a curiosity and a novelty check-off than for its visual interest.

Consigli per l'osservazione

A serious test of dark skies and aperture. At magnitude 13.6 it requires at least a 10-inch telescope to have a realistic chance, 12-inch or more for a confident sighting. The nearby glare of Polaris does not help; offset Polaris to the edge of the field at 200-300x and look for a tiny round fuzzy patch less than half a degree away. Because it is circumpolar from the entire northern hemisphere, it is observable year-round — useful when no other targets are well-placed. Plate-solving a wide-field image in advance is the easiest way to pinpoint it.

Storia

Discovered by Lewis Swift on November 19, 1885. The positional nickname 'Polarissima Borealis' was coined by amateur observers in the early 20th century as a matching-pair companion to 'Polarissima Australis' (NGC 2573), the equivalent nearest-the-pole galaxy in the southern hemisphere. The two names have persisted in amateur lore as a 'polar doublet' objective — bagging both requires travel to opposite hemispheres.

Curiosità

Despite its name, NGC 3172 is not the single closest galaxy to the north celestial pole in absolute terms — several much fainter galaxies lie closer, but none have historic NGC designations. As the north celestial pole slowly drifts due to precession, NGC 3172 is gradually moving away from its close-pole position — in about 12,000 years the pole will have moved far enough that it won't be 'polar' anymore, and the Vega region will take over instead.

Osservare

1Proprietà

Magnitudine 13.6
Dimensione angolare 1.1′ × 1.0′
Angolo di posizione 85°
Distanza 283.98 million ly
Tipo di galassia Lenticular (S0)
vF, R, gbM, *11 s 2', Polarissima Borealis

Posizione e identificatori

RA 11h 47m 14.0s
Dec +89° 05' 35.2"
Costellazione Orsa Minore (UMi)
Catalogo NGC 3172

2Facilità di osservazione

Accedi e configura la tua attrezzatura e località predefinita per vedere una riga personalizzata.
Telescopio Bortle 3 Bortle 4 Bortle 5
Rifr. 80mm M. diff.+ M. diff. M. diff.
Newt. 150mm Diff. Diff. M. diff.+
C8 203mm Diff.+ Diff. Diff.
Facile Medio Difficile Molto difficile Impossibile

Bortle 3 = rurale · 4 = periferia · 5 = suburbano

Medio con Seestar S50

3Visibilità

Imposta una località nelle impostazioni per vedere i dati di visibilità.

Periodo migliore Feb – Apr (peak: Mar)

4 Vista oculare

Accedi per impostare la tua attrezzatura
125x CV reale: 0.4° Mag. lim.: 13.6
N E

Polarissima Borealis · 1.1′×1.0′ · N su, E sinistra

5 Miglior Ingrandimento

Esplorare

6 Brillanza superficiale

7 Decodificatore di morfologia

8 Inclinazione e forma reale

9 Spostamento verso il rosso

10 Comparatore di dimensioni

Scoprire

11

Macchina del tempo della luce

12

Viaggio Relativistico

Vicini nel cielo

Altri bersagli a pochi gradi — sposta un po’ il telescopio e continua a esplorare.

I punteggi di visibilità assumono un Newton da 150 mm con Bortle 4.

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