I’ve been meaning to tell you about the tiny constellation Delphinus the Dolphin, and I’m happy to get to it finally.
Less than 100 years ago, the International Astronomical Union officially divided the sky into eighty-eight constellations to standardize the night sky worldwide. Forty-eight of those constellations were cataloged by the Greek astronomer Ptolemy in the 2nd century. Since then, the other 40 have been gradually added, many of them in the southern hemisphere.
Delphinus the Dolphin is one of Ptolemy’s original constellations. Even though it’s small and dim, it’s very distinct. It’s one of the few constellations that really looks like what it’s supposed to be. Even though it’s the 19th-smallest constellation, it’s one of my very favorites. I love pointing it out at stargazing classes and parties. Once you see it, you’ll never forget it. Delphinus is made up of a petite, skinny diamond of faint stars that outlines the torso and head of the little dolphin and a single faint star that marks the tail. Delphinus is swimming in the celestial sea in the western sky these early evenings after twilight.
The best way to find Delphinus is by using the famous “Summer Triangle.” Even though we’re well into November, the Summer Triangle is still visible in the western sky and is very easy to spot. Just look for the three brightest stars you can see in the western sky and that’s it.
This triad of bright stars comprises stars from three separate constellations, each being the brightest star in their respective constellation. If you face west, the brightest star you’ll see will be Vega, on the right corner of the triangle. A little to the upper left of Vega is Deneb. Altair is the brightest star in the constellation Aquila the Eagle in the lower corner. It’ll lead you to Delphinus. Just look to the upper left of Altair, and you’ll find the little dolphin.
Even though the five main stars that make up dainty Delphinus look faint to us, nothing could be further from the truth! Each one of those stars is much larger and way more powerful than our sun, and they kick out much more light and energy than our home star. Their faintness in our night sky is simply due to their vast distance from us. They range from 95 light-years to over 360 light-years away, and just one light-year is almost 6 trillion miles.
Throughout the ages, people have used constellations to tell stories tied to local religion or mythology. That’s certainly the case with Delphinus. Many early Hebrew towns saw Delphinus as a whale, reminding them of the Old Testament story of Jonah and the whale. Early Christian settlements saw the little diamond of stars as the Cross of Jesus.
I love the Greek mythology tales about Delphinus. It involves Poseidon, the god of the sea. As with most Greek gods, Poseidon was quite a playboy who got around in his youth. After many years he tried to domesticate himself and get married. He set his sights on Amphitrite, one of the many Nereids that occupied his domain. Nereids, or sea nymphs, were like mermaids, according to legend, and it was their mission to provide safety and protection for sailors and fishermen.
Despite Poseidon’s attempted charm and all his wooing, Amphitrite was underwhelmed and avoided him like the plague. She hated the god of the sea! Poseidon wasn’t about to quit his ill-fated pursuit. He was determined to have his prize, so he kidnapped Amphitrite and put her in a cage! How about that for charm and class?
One day, when one of Poseidon’s guards opened the cage door, she screamed at him at the top of her lungs. It was such a high pitch that it stunned the guard just long enough for her to slip out behind him, swimming her tail off as fast and far as she could. Even after Amphitrite’s great escape Poseidon didn’t give up. He vowed to change his ways and actually become a nice guy. He sent Delphinus, his faithful and magical dolphin, to search for Amphitrite. Not only could Delphinus talk but he was a diplomat as well. He managed to find Amphitrite and persuaded her to give Poseidon another chance. She finally agreed, climbed on Delphinus’s back, and rode back to the god of the sea. They were happily married, and as a reward, Poseidon placed his faithful dolphin in the heavens as the constellation we still see thousands of years later.
It might take a little work to find the little Dolphin in the sky, but it’s so worth it!
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and adventurepublications.net. Mike is available for private star parties. You can contact him at [email protected]