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Tracking dolphin, horse across night sky

Take 'tiny' challenge

This week in Starwatch I’m deep tracking a bit. There are 80 constellations that can be seen from Earth and they’re all different sizes.

Delphinus the Dolphin is the 19th smallest, and Equuleus the Little Horse is the second smallest, and they’re snuggling up in the western sky this month.

They also happen to be the smallest mammal constellations that can be found anywhere in the nighttime sky. What they lack in size they make up for in coolness. Even in the heavens good things come in small packages.

Let me start with Delphinus. It’s one of those few constellations that looks like what it’s supposed to be. I love showing it to folks at my stargazing parties. It’s definitely one you can easily remember.

Delphinus is made up of a small but distinct sideways diamond of stars that outlines the torso and head of the little Dolphin, and a single star just to the lower right of the diamond marks the tail.

Currently, Delphinus is swimming about in the western celestial sea in the early evenings. The starry dolphin appears to be jumping vertically. Delphinius always reminds me of the old 1960s TV show “Flipper.” OK, I’m showing my age.

The best way to find Delphinus is by using the famous “Summer Triangle”. Despite the fact that we’re well into autumn, the Summer Triangle is still hanging in there in the Butler western sky.

It’s very easy to see. Just look for the three brightest stars that you can see about halfway from the western horizon to the overhead zenith. This trio is made up of the brightest stars in three separate constellations.

Facing west, Vega is perched on the right side and is the brightest star in the Summer Triangle. Vega also serves as the brightest star in the constellation Lyra the Lyre, or Harp.

The dimmest star of the triangle is Deneb, the brightest star in the constellation Cygnus the Swan. On the lower left corner is Altair, the brightest luminary in the constellation Aquila the Eagle.

It’s from Altair that you start your quick search for the diminutive dolphin. Just gaze about two fist-widths at arm’s length above and slightly to the left of Altair for a faint but visible to the naked eye little vertical diamond that outlines the torso of Delphinus. The celestial Dolphin’s tail is marked by another faint star just below the diamond.

Heavenly looks can be deceiving. Even though the five main stars that outline the body and tail of Delphinus the Dolphin are fairly faint, each one of them is much larger and produces more light and energy than the sun, our closest star.

Their faintness in our night sky is simply due to these stars being a heck of a long ways away. They range in distance from 95 light years to more than 360 light years away. Just one light-year, the distance that a beam of light travels in one year’s time, is almost 6 trillion miles.

Now for extra credit see if you can spot Equuleus the Little Horse.

This will be a real challenge because it’s less than half the size of Delphinus and its stars are just as faint or fainter. About all there is to it are four stars that make a tiny and skinny lopsided trapezoid that allegedly makes up the head of a tiny horsey. I know ... that’s a big time stretch.

Both Delphinus and Equuleus are two of the original 48 constellations listed by the famous astronomer Ptolemy in the 2nd century, and as with all constellations different cultures have their own names and mythology associated with them.

Equuleus the Little Horse was thought to be the little brother of the famous winged horse Pegasus. That makes sense to me, since the constellation Equuleus is right next-door in the sky to the constellation Pegasus that is flying high in the south half of the evening sky.

Next month I’ll feature the giant flying horse. In the meantime, see if you can find two of the tiniest constellations in the night sky. It is at least a “tiny” challenge.

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and author of the book, “Stars; a Month by Month Tour of the Constellations” published by Adventure Publications available at bookstores at http://www.adventurepublications.net.

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