Spooky Space: A late Halloween treat

Back at the beginning of October, I put together a star talk for my planetarium job all about “spooky” space objects. The show did decently, but I really wanted to share it with a wider audience. So here’s my late Halloween treat to everyone.

Most of the spooky astronomical objects I’ll be talking about are nebulae (singular nebula)- massive interstellar clouds of gas and dust that are the birthplaces of stars. There are three main kinds of nebulae:

Reflection nebulae, which are illuminated by the light from nearby stars reflecting off the particles within it.

Emission nebulae, wherein the gas and dust themselves glow due to being energized by the radiation from nearby.

Planetary nebulae, which are spherical shells of superheated gas thrown off by a dying star (they’re confusingly called “planetary nebula” because their round shape made them look like planets in early telescopes).

On Earth, we often form images out of the random shapes of clouds, so it’s not surprising that astronomers have extended this habit to clouds in space. Let’s look at a few of them here.

Image Credit: NASA/ESA

IC 63, The Ghost of Cassiopeia Located, as you can guess, near the constellation Cassiopeia. Hydrogen in IC 63 is being bombarded by the intense ultraviolet radiation of Gamma Cassiopeiae, a blue-white subgiant star. This radiation charges the hydrogen particles in the cloud with energy, causing them to give off the eerie red glow seen in this image. Visible light from Gamma Cassiopeiae is also reflecting off the cloud, creating the blue color seen near the top of the image. Thus IC 63 is both an emission AND a reflection nebula. This intense radiation is also blasting away at the cloud, sculpting it into the eerie figures seen here.

Image Credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona. Used under the Creative Commons Attribution-Share Alike 3.0 Unported license

The Ghost Nebula, vdB 141 A reflection nebula located in the constellation Cepheus near Cassiopeia. The creepy humanoid figures with raised arms are “fingers” of gas being sculpted by the radiation from nearby stars. Within each finger is an embryonic star, feeding off the cloud’s gas and dust. The amber-brown glow comes from the reflected light of nearby mature stars.

Image Credit: NASA/ESA

Cat’s Eye Nebula NGC 6543: A planetary nebula in the constellation Draco, NGC 6543 is a series of concentric gas shells thrown off at regular intervals by a dying star.

Image Credit: NASA/ESA and STScl

The Bat Shadow- HBC 672: As a star coalesces out of its parent nebula, it begins to spin and its gravity pulls some of the gas and dust into a ring orbiting its equator.  Eventually this ring condenses into planets, asteroids and other solid bodies. Astronomers have obtained many fascinating and beautiful pictures of stars with these dark equatorial rings. My personal favorite- and one particularly appropriate for the spooky autumn season- is this picture of the young star HBC 672. Here the star’s dust ring is partially blocking the light it’s emitting, creating two prominent V-shaped “wing shadows”- visible in the upper part of the image- against the bright nebula around it.

HBC 672 is located in the constellation Serpens, a rather dim constellation associated with Hercules.

Image Credit: NASA, ESA, .R. O'Dell (Vanderbilt University), and M. Meixner, P. McCullough, and G. Bacon (Space Telescope Science Institute)

Helix Nebula NGC 7293: A creepy eye-like planetary nebula located in Aquarius. And one of the closest planetary nebula to Earth.

Image Credit: Göran Nilsson & The Liverpool Telescope

. Licensed under the Creative Commons Attribution-Share Alike 4.0 International license

The Skull Nebula, NGC 246  A planetary nebula located in the constellation Cetus. This nebula is moving rapidly through space and interacting with the interstellar dust in front of it, causing the leading edge- at the top here- to glow brighter than the rest of the cloud.

Image Credit: NASA/STScl Digitized Sky Survey/Noel Carboni

The Witch Head Nebula, IC2118: Located in Orion, this reflection nebula is illuminated by the glow of the blue supergiant star Rigel which forms the left knee of the constellation.

Image Credit: NASA and STScl

The Shadow Person Nebula NGC 1999: Another nebula located in Orion, this cloud reflects the light from a bright star known as V380 Orionis.  The creepy black silhouette in the middle was originally thought to be a dark cloud blocking the light behind it. It’s now known that this object is actually a void of space in the middle of the cloud, possibly caused by nearby stars blowing the gas away.

Image Credit: ESA, NASA, & Mohammad Heydari-Malayeri (Observatoire de Paris, France)

The Ghost Head Nebula NGC 2080: Located in the southern hemisphere sky in the constellation Dorado. The Ghost Head is an emission nebula formed from ionized gas. The eyes of the ghost, A1 and A2, are hot, glowing blobs of hydrogen and oxygen. A1 is illuminated by a single star, but A2 is lit by multiple celestial bodies. Both blobs are very young- only 10,000 or so years old- evident by the fact that they have not been blown away yet by the solar wind of the stars inside them.

Image Credit: European Southern Observatory (ESO). licensed under Creative Commons Attribution 4.0 International

Skull and Crossbones Nebula NGC 2467 Also located in the Southern hemisphere. This object Is actually several star-forming regions widely separated in space. From Earth, though, they all lie along the same line of sight and thus appear to be one single mass.

There are, of course, plenty of spooky objects in the night sky that aren’t nebula. For instance:

Image Credit: NASA, ESA, AURA/Caltech, Palomar Observatory

The Pleiades. Stars are born in nebulae, condensing down out of the diffuse gas and dust under the force of gravity. This often results in several stars forming in close proximity to each other, in a group called an open cluster.  Such is the case with the Pleiades, also known as the Seven Sisters. Located on the back of the constellation Taurus, the Pleiades are the easiest cluster to see from Earth. As the cluster’s nickname suggests, seven of the brightest stars are visible with the naked eye, though a good telescope will reveal hundreds more.

Centuries ago the Pleiades were said to be highest in the sky around All Hollow’s Eve, a time halfway between the autumn equinox and the summer solstice when the souls of the dead were believed to wander the Earth.  Because of this, the Pleiades came to be associated with the dead- though not necessarily in a negative or malignant way.

It should be noted that nowadays due to the slow wobble of the Earth’s axis- known as precession- the Pleiades are actually at their highest point in the sky around November 21.

The Hyades in Taurus.
Image Credit: Till Credner. Licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

Hyades Another open cluster with a creepy association. The Hyades form the V-shaped face of Taurus. They are mentioned in the Weird horror stories of pulp author Robert W. Chambers. In Chambers’ fiction the Hyades are associated with The King in Yellow, a mysterious play that drives anyone who sees it mad. In the play, the alien city of Carcosa, which is haunted by the King, is said to lie somewhere among this star cluster.

Aldebaran, the red giant star that forms the eye of Taurus, appears to lie within the Hyades. This is just a trick of perspective, though, since both Aldebaran and the cluster lie along the same line of sight when viewed from Earth.

The constellation Perseus with Medusa's head, depicted in Urania's Mirror, a series of 32 celestial cards published in 1824. Here Algol is on the top of Medusa's forehead for some reason. 
Image Credit: Public Domain, image restored by Adam Cuerden.

The Demon’s Eye, Algol: This star is located within the constellation Perseus, which is named after the Greek hero who slew the gorgon Medusa. Early observers noticed that this star would dim and brighten over the course of several days. At the time people had no explanation for this phenomenon, so the star was called “the Demon’s Eye” because of its seemingly supernatural ability. With more advanced telescopes, astronomers discovered that Algol is an eclipsing binary- that is, two stars orbiting each other.  Binary and even multiple star systems are common throughout the galaxy due to the fact that stars are born so close together (our own sun, which is by itself, is a comparatively rare occurrence).  The two stars of Algol happen to be oriented so that when they’re seen from Earth one star will periodically block the light from the other one. When both stars are visible from Earth, Algol appears bright, but when one star is eclipsed by the other, Algol dims. Algol is often portrayed as the winking eye in Medusa’s severed head, which Perseus holds.

I hope you’ve enjoyed my tour of the Spooky Skies. In the future I might transcribe some more of my themed planetarium shows in posts here.