THE SOUTHWORTH PLANETARIUM
70 Falmouth Street Portland, Maine 04103
(207) 780-4249 usm.maine.edu/planet
43.67° N 70.27° W
Founded January 1970
2022-2023: XCVI
Sunrise: 5:09 a.m.
Sunset: 8:08 p.m.
Civil twilight begins: 4:35 a.m.
Civil twilight ends: 8:42 p.m.
Sun's host constellation: Taurus the Bull
Lunar phase: Waxing crescent (15% illuminated)
Moon rise: 7:54 a.m.
Moon set: 12:18 a.m. (5/24/23)
Julian date: 2460087.29
"Made from the best stuff off Earth"
THE DAILY ASTRONOMER
Tuesday, May 23, 2023
The Castor Six
What does one see when venturing outside to admire the unbounded -and preferably clear- night sky? Most people would reply, 'stars,' but, honestly, we shouldn't accept that sound and logical answer. And before the double-fisted Captain Bligh hops out of your hippocampus and demands, 'What's wrong with it?!' we'll explain.
We've never seen a star. Not once. Ever.
We see a faint, point-like, flicker of light emanating out of a star from an unfathomably long distance . Light that's literally traveled through space for many years, if not decades or centuries. Even if that light delights the eye and dazzles the senses -which it often does- one should never mistake it for the real thing. Were we given the opportunity to encounter a real star, even a comparatively low-energy red dwarf, up close, personal and without filtration -apart from that which we'd need to protect our eyes and bodies from utter annihilation, of course- we'd experience the most overwhelming, spiritually shocking moment of a thousand lifetimes, assuming we'll be allotted that many. An intensely hot, fiercely turbulent sphere issuing forth prodigious quantities of energy in every direction without so much as a microsecond of let up. The frenzied current of stellar winds, the incandescent heat of the pulsing granulations, not to mention the million-mile high prominences and flare spasms.
The difference between seeing the stars from the safety of our backyards and confronting them in person is similar to the difference between seeing a photo of Manhattan on a refrigerator magnet and actually experiencing the atheism-annhiliating crush of traffic on the George Washington Bridge.
Perfect case in point: Castor
One will see Castor, the second brightest star in Gemini, low in the western evening sky tonight. It will remain insight at least until early June, when this lovely star will dissolve into the dusk. From our perspective, it seems like little more than a moderately bright star: a firefly gently descending along the western mid-spring sky.
It isn't.
When you observe Castor, you're seeing the combined light of six stars: two hot white stars far more massive and luminous than the Sun and four dwarf stars. Regard the image below.
Even though Castor is relatively nearby at a distance of 51 light years, it is far enough away to effectively conceal its six component members. Were we to set these stars in motion and watch them in a time-lapse, we'd observe a dizzying array of orbital motions: the twin components around each other and the pairs around the other pairs. So far no planets have been detected in the system. One can only imagine the sight of the sky from the perspective of any such planet.
Just be aware that when you see Castor, you're not seeing Castor at all. It isn't a quiet little orb adorning our sky. It is an unfathomably large assemblage of stars all gravitationally bound to each other. Unfathomably powerful, intensely energetic and far beyond our comprehension.
Well, one could make the same statement about any star.
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