Bright stars outline the familiar shape of the Christmas Tree Cluster in this visible-light image, which has been rotated 180°. Another famous structure, called the Cone Nebula, sits atop the tree. It's located in the constellation Monoceros. (Image: NOAO/AURA/NSF) Mona Evans "Monoceros the Unicorn"

Rosette Nebula (NGC 2237). (Image: Adam Block & Tim Puckett) The red color is hydrogen gas energized by a hot star - it's an emission nebula. The “stem” is formed by a trail of the same glowing hydrogen gas. The nebula is 5000 light years away in the constellation Monoceros.Mona Evans "Monoceros the Unicorn"

The Red Square Nebula (MWC 922) (Image Credit & Copyright: Peter Tuthill (Sydney U.) & James Lloyd (Cornell)) The hot star system MWC 922 seems to be embedded in a square nebula. No one knows how this came about. Infrared combined image from Mt. Palomar in California & the Keck-2 Telescope in Hawaii. Mona Evans, "Cosmic White Christmas"

Eyes and Nebulas. ©Mona Evans, “Nebulae”

R Sculptoris. This is a dying star shedding its outer layers. The image was captured by the Atacama Large Millimeter Array (ALMA) high in the Chilean desert. The planetary nebula is visible in radio emission, which is invisible to our eyes. Mona Evans, "Cosmic White Christmas"

The Witch Head Nebula. It glows from light reflected from bright supergiant Rigel - Orion's left foot! Although Rigel is blue, the nebula is blue because the dust scatters blue light more efficiently than the longer wavelengths. (Image: George Greany) ©Mona Evans, “Nebulae”

A group of baby stars form a "stellar snowflake" in Spitzer Telescope observations of a dusty region near the Cone Nebula. It's sometimes called the Snowflake Cluster. Mona Evans, "Cosmic White Christmas"

NGC 1514, discovered by William Herschel in 1790. It's also known as the Crystal Ball nebula and this image, which is the result of 10 hours of exposure using 4 filters, it certainly looks like one. Herschel would have loved seeing it like this! (Image credit: Adam Block/Mount Lemmon SkyCenter/University of Arizona) Mona Evans, "Nebulae"

Red Rectangle Nebula. There is an aging binary star at the center of the nebula, which will probably eventually become a planetary nebula. Astronomers are still trying to work out what's going on in this complex nebula. (Image Credit: ESA, Hubble, NASA; Reprocessing: Steven Marx, Hubble Legacy Archive) Mona Evans "Monoceros the Unicorn"

Blue snowball nebula (NGC 7662). A planetary nebula in the constellation Andromeda. The nebula was formed by the aging central star losing its outer layers of atmosphere. (Image credit & copyright: Chris Vedeler) Mona Evans, "Cosmic White Christmas"

Peony nebula star - WR 102ka - is located in the Peony nebula, the reddish cloud of dust in and around the white circle, surrounding the star. (Image: Spitzer Space Telescope) Mona Evans, "Nebulae"

Orion Nebula. [Image Credit: NASA, ESA, M. Robberto (STScI/ESA) et al.] It's the nearest star-forming nebula to us and much of the dust has been blown away giving an even clearer view. The image has been sharpened up by using data from both the Hubble and ESO's La Silla telescopes. ©Mona Evans, “Nebulae”

Butterfly Cluster (M6 / NGC 6405). Bright open star cluster in the constellation Scorpius. Its popular name reflects the butterfly shape you can see in this picture. About eighty stars have been identified, but the cluster probably has over three hundred, mostly hot blue stars. (Image Credit: N.A.Sharp, Mark Hanna, REU program/NOAO/AURA/NSF) Mona Evans, "Scorpius the Scorpion",

Butterfly Cluster. (Yes, I guess it does look a bit like a butterfly.) An open star cluster also known as M6. You should be able to pick out the orange giant BM Scorpii which contrasts with the hot, blue stars which comprise much of the cluster. Estimates vary, but it's around 1600 light years away. (Image Credit: AURA, NOAO, NSF) Mona Evans, "Creepy Crawlies in Space",

Light Echoes from V838 Mon. In Jan 2002 the star's outer surface suddenly expanded, making it extremely bright. And just as suddenly, it faded. The flash seems to expel material, but the image shows an outwardly moving light echo of the flash. Light Is reflected by ever more distant rings in the dust around the star. [Image Credit : NASA, ESA, H. E. Bond (STScI)] Mona Evans "Monoceros the Unicorn"

Cluster surrounded by clouds of interstellar gas and dust—the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. - Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

M44: The Beehive Cluster (Image Credit & Copyright: Bob Franke)

NGC 457 (also known as Skiing Cluster, Owl Cluster, ET Cluster). Open star cluster in Cassiopeia, discovered by William Herschel in 1787. (Image credit: Henryk Kowalewski)

Quintuplet Cluster. It's most famous star is the Pistol star, the most luminous known star in the Galaxy. On the left is the Hubble image from 1999. On the right is a new one from 2015 - quite a difference in resolving power for the fabulous space telescope.

Open star cluster Messier 50 in the constellation Monceros. (Credit: Canada-France-Hawaii Telescope / Coelum) Mona Evans "Monoceros the Unicorn"

Stars in the cluster NGC 2547. The cluster is in the constellation Vela (the sail). These bright blue stars are quite young, between 20-35 million years old. This doesn't sound young, but our Sun is middle-aged at 5 billion years, so these stars are just babies. (Image: MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile)