A Colorful Universe

Posted by Kelly Whitt Apr 10, 2008

Is there a space object for every color of the rainbow? One of my favorite objects of all is one that shows a rainbow of colors in one place: the Rho Ophiuchi Cluster and Nebula.

• Red - There are many space objects that are red. Mars is considered red as well as the Great Red Spot on Jupiter, however in reality both are a bit more orange in color. The vast majority of nebulae, when photographed, appear red. One example is the Red Square Nebula. There are also many red stars, including Betelgeuse.
• Orange - Mars and the Great Red Spot, as mentioned above, are described as red, but usually appear more like an orange hue in real life. The Flame Nebula is a good example of an orange-hued nebula.
• Yellow and Blue - I put yellow and blue together because so often you see the one color by benefit of it being near the other color. The double star Albireo is famous as being a blue and yellow star pair. There are a number of galaxies that also combine yellow and blue, with lighter colored cores and bluer in the arms, plus yellow and blue star forming regions. The colliding galaxies M51 illustrate the yellow/blue combination well.
• Green - Green is the most common color found close to home, in the aurora or the sun's green flash. Uranus is also a greenish blue, and the Cat's Eye Nebula has a wonderful green edging.
• Purple - Purple shows up often on the outskirts of red nebulae. The Witch Head Nebula also sometimes looks purple instead of blue depending on the processing.