Big dipper constellation in a dark blue sky

Minnesota Skies: September 2021

Learn more about the intriguing names of celestial sights in this blog post!

Published08/31/2021 , by Thaddeus LaCoursiere

Intriguing Names for Celestial Sights

Scanning over a star map or paging through your favorite night sky observing guide, you might be struck by the names associated with various deep sky objects: the Cheeseburger Nebula, the Deer Lick Group, or Gomez’s Hamburger. These names are at once fanciful, bizarre, confusing, and definitely a sign that astronomers get very hungry on those late nights of peering into the furthest corners of the universe. Read on for four oddly named objects you can find in our early fall sky.

We start at the end—the end of a star’s life that is! When a star similar in mass to our Sun reaches the end of its life, fusion in the core starts to shut down, and gravity compresses it. At the same time, the gas and plasma in the star’s outer layers begin to puff off into space. The energy from the compressed core—known as a white dwarf—energizes those outer layers, causing them to emit light. This entire structure is known as a planetary nebula and it contains a multitude of atoms and molecules formed within the star during its lifetime and at the end. Medium mass stars in particular contain a great deal of oxygen, formed during the CNO cycle (carbon–nitrogen–oxygen).  The abundance of oxygen—and the light that it gives off—gives astronomers a great way to understand the structure of planetaries. Triply ionized oxygen (OIII) also gives the first object you can find in the night sky its name: the Blue Snowball.

The Blue Snowball Nebula, brightly colored with purple and green

The Blue Snowball Nebula, Credit: B. Balick (U. Washington) et al., WFPC2, HST, NASA

At around 2,500 light years away but at a bright magnitude 8, this planetary nebula is an excellent target to start with for amateur astronomers. Tracking it down is also a good way to build your star-hopping skills. The Blue Snowball lies about a hand length above the Fall Square (the Great Square of Pegasus), making the peak of a triangle with the top edge of the Fall Square forming the bottom. It’s also just two-finger widths away from the small curve of three stars formed by Llamba, Kappa, and Iota Andromedae.

Taking a detour from star death and heading further up in the sky, there’s a straightforwardly named cluster of stars not too far away. Unlike most clusters which seem to receive their names because someone, somewhere, somehow saw a shape in the sky, the Star Lizard Cluster (also known as NGC 7209) most likely gets its name from its position in the cosmos—it’s right next to the constellation of Lacerta, the Lizard. In fact, it’s only three finger-widths away from the diamond of Lacerta’s head. These four stars can be tracked down by first finding the square portion of Cepheus, the King, visible high overhead to the north in the fall. Cehpheus also resembles an upside-down house in the sky, and the bottom of the house (higher up in the sky!) points up and to the east to Lacerta’s head. Now looking roughly east northeast, go up from the apex of the diamond the aforementioned three finger-widths to see this 150 member strong group of stars, at only about 400 million years old they’re sure to make you feel young again!

A diagram of the Cygnus, featuring Deneb and the Northern Cross

If all this star-hopping is tiring you out, our final stop in the sky will give you a place to rest your head: NGC 7027. To find it, start by looking upwards to the very top of the sky, known as the zenith, you can easily spot the bright star Deneb at the center of Cygnus, the Swan. Deneb is one corner of the famous Summer Triangle, which still graces our sky for several hours in the early fall. From Deneb look down to the southeast, only about three finger widths away to spot this planetary pillow. This is indeed another planetary nebula, similar to the Blue Snowball. Yet unlike that multi-thousand year old object, the Pink Pillow is only 600 years old! This young age means that the outer layers have only barely left the original star, making the nebula a bright, compact object in the eyepiece of a telescope. The smallness is also helped by the distance—about 3,000 light years away—but it’s truly small in the grand scheme of things. Whereas the average size for planetaries is about 1 light year across, NGC 7027 measures a tiny 0.2 light years wide at its widest. Only about one trillion miles! However its slightly squeezed shape, along with the reddish light of sulfur II captured by the Hubble Space Telescope, lends itself to its slightly more common name: the Pink Pillow Nebula.