APOD: IC 2118: The Witch Head Nebula (2023 Oct 04)

[APOD Robot]

IC 2118: The Witch Head Nebula

Explanation: Does this nebula look like the head of a witch? The nebula is known popularly as the Witch Head Nebula because, it is said, the nebula's shape resembles a Halloween-style caricature of a witch's head. Exactly how, though, can be a topic of imaginative speculation. What is clear is that IC 2118 is about 50 light-years across and made of gas and dust that points to -- because it has been partly eroded by -- the nearby star Rigel. One of the brighter stars in the constellation Orion, Rigel lies below the bottom of the featured image. The blue color of the Witch Head Nebula and is caused not only by Rigel's intense blue starlight but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in planet Earth's atmosphere are molecules of nitrogen and oxygen.

<< Previous APOD

This Day in APOD

Next APOD >>

[Ann]

The Witch Head has been the APOD before!

The Witch Head Nebula, the APOD of October 4, 2023. Credit: Abdullah Al-Harbi.

---

The Witch Head Nebula, the APOD of January 24, 2022. Credit: José Mtanous

---

The Witch Head Nebula looks quite red in José Mtanous' picture (possibly because José Mtanous may have used used a red hydrogen alpha filter to enhance the red background of the Witch Head Nebula). And indeed, for a blue reflection nebula, the Witch Head Nebula is actually quite non-blue. Below is one of my favorite Witch Head images:

The Witch Head Nebula. Author unknown.

You can see how much bluer bright star Rigel is than the Witch Head Nebula. "She" looks scarily witch-like here, with the kind of dead gray skin that you might expect from an ominous fictitious being.

Ann

[bls0326]

Ann: Thanks for showing the previous APOD with Rigel in the picture. Also thanks for Witch Head Nebula labels. Seems to me that the more detailed pictures/information we have now makes it difficult to see the shapes folks saw in the past.

[orin stepanek]

Is she a witch or a bitch? I can't tell which! Can you tell that
Halloween is coming!

[johnnydeep]

Yup, the witch is looking directly at Rigel alright!

[Astronymus]

Yeah, who doesn't remember the Battle of Witchhead?

[johnnydeep]

Yeah, who doesn't remember the Battle of Witchhead?

Nice. I didn't know the reference - https://en.androwiki.org/Battle_of_Witchhead

Battle of Witchhead

The Battle of Witchhead Nebula was the final action of the Nietzschean Rebellion, or Tactical Offensive, depending on who you talk to. Despite its important place in history the exact events are subject to debate and speculation, mainly because when the battle was finished, few who had seen it remained to tell the story. It was not until the Andromeda Ascendant was transported to the Battle from 300 years in the future that the true nature of it was revealed.

In CY-9786 the few remaining High Guard Ships, roughly 100, assembled in the Nebula under orders from Admiral Constanza Stark, from there they were to launch a daring attack on the Nietzschean Homeworld, Fountainhead. The Nietzscheans somehow learned of this plan and assembled their own fleet, numbering 500 by most historical accounts but which was actually made up of 1,500 ships. This was known to some however many considered it a myth.

[starsurfer]

Does IC 2118 have ERE?

[johnnydeep]

Does IC 2118 have ERE?

Maybe? See https://www.researchgate.net/figure/Bes ... 1_45927059

But IC59 and IC63 definitely do? See https://academic.oup.com/mnras/article/ ... 33/3813441