Salutations celestial sight seers!
I'm David Fuller, welcome to Eyes on the Sky; what's up this week?
Ummm....
Orion!
Well, more specifically, the "sword" region of this constellation, measuring only 2 degrees
in length of sky, but packed with awesome sights to see.
Somewhat centered between the left "belt" star Alnitak, and the two "knee" stars of
Saiph on the left and Rigel on the right, is the Orion Nebula.
(Hallelujah chorus) Yes... this part of the sky IS that good.
Also known as Messier 42, this diffuse nebula is about 24 light years across that contains
the mass of about 2,000 of our Suns.
What to see?
First the tiny Trapezium stars in the brightest section of the nebula; use lots of magnification
to tease out all four Trapezium components, and with larger scopes?
Some can split 5 or 6 total stars here!
But what else?
Well, color in the nebula -- maybe, though not like what photographs show.
Seeing color depends on a lot of factors, but largely your own eyes, and next, the aperture
of your telescope.
M42 is one of the brightest nebula in the entire sky, so it sends a lot of photons our
way.
But as for color, well, some people just never see it visually at night.
On our retinas, the cells called rods work in low light, and cones in brighter light.
So to get more light there, use more telescopic aperture.
In a 10" reflector, I have seen blue, green, orange, and hints of red in this nebula.
But in a 70 millimeter refractor, I just see a lot of grey and a touch of blue.
But you can increase your odds of seeing color in the Orion Nebula by doing this.
That's right: Intentionally ruin your dark adaptation so you're viewing photopically;
this will force your eyes cones to work, and you MAY perceive color then.
Dark Sky Fact: The Astronomy Club of Asheville North Carolina got a city ordinance passed
in 2008 to reduce light pollution by requiring shields to be placed on all non-compliant
fixtures.
The local energy company didn't swap out or shield any fixtures during that time.
But!
The problem is being fixed.
Find out more about this story at eyes on the sky dot com.
To observers, the Orion Nebula is sort of like a moth to a light, don't overlook other
targets nearby.
Messier 43 is just to the north of M42.
If it weren't so close to the larger nebula, it would be a sight many amateurs would repeatedly
seek out.
A bit to the south is Iota Orionis, here, which has the appropriate Arabic name "Na'ir
al Saif" which means, "The Bright One of the Sword," and accordingly, it IS the brightest
star in Orion's sword.
To its southwest just 8 arc minutes away in the same medium field of view is the wide
double star Struve 747.
These B-class blue-white stars are not gravitationally related, as the brighter one is a quite distant
1,800 light years, and the dimmer one 3 times as far at 5,900 light years away.
Its light reaching your eyes left that star before the beginning of the Bronze Age.
Wow.
Yeah.
Oh, and look a few arc minutes west of there; dimmer, but similarly spaced, are the stars
of Struve 745.
Here's the odd thing: They are MUCH closer -- just 150 and 280 light years away.
And lastly, look just north of M42 and 43.
Skip past the triple pairing at 45 Orionis, and check out the somewhat random-looking
open cluster of NGC 1981, sitting 1300 light years away, about 45 light years closer than
M42 is.
Lots more on these objects in the blog at eyes on the sky dot com.
Along The Ecliptic: Venus sits still in the southwest, but will start dropping quickly
towards the horizon, so look for its thin crescent soon.
Jupiter is visible most of the night as it continues trekking slowly through Gemini.
In the morning hours Mars gets a lunar visit in mid-week, followed by Saturn getting the
lunar visitor on the weekend.
That's all for this week.
Keep your eyes on the sky and your outdoor lights aimed down, so we can all see, what's
up.
I'm David Fuller, wishing you clear and dark skies.