Nebula M78

Designation: Messier 78 & NGC 2068, in the constellation of Orion.
Visual magnitude:  +8.3
Apparent size: 8 x 6 arc-minutes.
Diameter: 3.7 light years.
Distance: 1600 light years.
Date: 2020-02-25
Exposure: 24 frames x 114 sec = 45 minutes.

Which is the brightest reflection nebula in the sky?

I don’t know!

At least I didn’t until I looked up M78 on my Sky Safari Pro app and found the pearl of wisdom which said M78 wins the honour. Now we’ll all get an extra point next time this question comes up in a pub trivia quiz – that is if the pubs ever open again.

That it’s the brightest reflection nebula surprised me, because you wouldn’t think it by looking at my modest forty-five minute exposure taken through the atmospherics of suburban Sydney – but remember it’s reflection nebulae we are talking about, not emission nebulae.

What else did I learn about this object?

  1. M78 is a cloud of interstellar dust which shines by scattering the light of two stars; and
  2. These two stars (10th & 11th magnitude) feature prominently in my image.

Yes – but how do we know it’s a reflection nebula?

Unlike an emission nebula with its discrete line spectra, a reflection nebula exhibits a continuous spectrum of star light which matches the stars which are responsible for illuminating it.

Can I see it – and what else is in the image?

M78 is not hard to find – you can pick it with binoculars in a decent sky, about 2.5° from Alnitak, one of the three Belt stars of Orion.

NGC 2071, an 8th magnitude reflection nebula, is the upper bright object visible in my image.

NGC 2064 and NGC 2067 are barely there – if you look hard enough – but will not stand out without the benefit of a darker sky with more contrast.

Follow this link to see my image with Astrometry.net annotated overlay.


Telescope Details
SkyWatcher Esprit 120 mm apochromatic 3-element refractor.
840 mm focal length @ f/7 with field flattener.
Baader L-Booster UHC-S light pollution filter 2458276.
SkyWatcher EQ6-R Pro mount.
Camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx)
ZWO ASI120 guide camera, using PHD2 software.
2018-03-10 Telescope & Roger
Images © Roger Powell
I’m a founder member of Macarthur Astronomical Society,
Australia. 🙃

8 Comments

  1. Wow, That is fantastic. Look at all the fun and the new things i have learned. You are a genius.
    Thanks for the research and for posting the results.
    Fran

    Liked by 1 person

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