Menu

38 Geminorum — Double Star in Gemini

Observable Double Star Excellent (61/100)

Sep: 7.4", Companion: mag 7.8

Magnitude 4.7m DoubleStar Gemini (Gem) Visible
Star Map
+ List + Plan

Observe

1Physical Properties

Magnitude 4.65
Spectral Type F0Vp
Star Color Yellow-white (B-V 0.30)
Distance 76 ly

2Position & Identifiers

RA 06h 54m 38.7s
Dec +13° 10' 40.0"
Constellation Gemini (Gem)
HR 2564
HIP 33202
HD 50635
SAO 96265
Flamsteed 38 Gem
Double Cat 5559
SIMBAD

3How easy to split?

Primary 4.7 mag Companion 7.8 mag Separation 7.4″
Sign in and configure your equipment and default location to see a personalized row.
Telescope Bortle 3 Bortle 4 Bortle 5
80mm refr. Easy Easy Easy
150mm Newt. Easy Easy Easy
C8 203mm Easy Easy Easy
Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

4Visibility

Set a location in User Settings to see visibility data.

Best season Nov – Jan (peak: Dec)

5Multiple Star System Triple C: optical

Components 3 (triple)
Component IDs AB
Separation 7.4″
Companion Mag 7.8
Position Angle 145°
Star Colors A: Yellow-white B: Orange
Discoverer STF 982
AB 4.8 A9Vp, 7.6 G6V, 1943.8y, a = 8.194". Combined mag., colors.

Separation over time

Period: 1749.9 y Eccentricity: 0.841 Now: 7.4", PA 142° + 0.04" in 5 years
0.00" 2.2" 4.4" 6.5" 8.7" 2025 2030 2035 2040 2045 7.4"

Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.

Eyepiece View

Log in to set your own equipment
80x Dawes: 1.9″ TFOV: 0.6°
Realistic = true angular size
N E 145°

A: 4.7 · B: 7.8 · Sep: 7.4″ · PA: 145° · N up, E right

Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

Explore

6

Size Comparison

Querying VizieR for stellar data…
7

Compare Stars

8

Spectral Classification

9

Hertzsprung-Russell Diagram

Loading HR diagram…
Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map
10

Stellar Lifecycle

11

Blackbody Spectrum

12

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

13

Stellar Fusion

Discover

14Stellar Notes

ADS 5559A.
0.029".
ADS 5559B, 23k/s.
15

Light Travel Time Machine

16

Relativistic Travel

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

NGC 2259
Medium+
Open cluster
Open Cluster mag 11.0 4.6° Monoceros
15 Mon
Medium+
Easy double, sep 3.0″
Double Star mag 4.66 4.7° Monoceros
Hubble's Variable Nebula
NGC 2261
Medium
Reflection nebula around a bright star
Reflection Nebula mag 10.0 5.8° Monoceros
BL Ori
Medium
Semi-regular variable, range 5.9–6.6
Variable Star mag 6.24 7.2° Orion
Show on Map

Explore Nightbase

Related knowledge, tools, and stories — no observation planning required.

Gemini
Mythology, bright stars, and deep-sky highlights.
Constellation
Double Stars — A Guide for Observers
Two suns where one appeared — how to find, split, and appreciate the night sky's finest pairs. From Albireo's gold-and-blue to the Sirius B challenge.
Article
Venus
Phases, transits, and the brightest planet in the sky.
Deep dive
}