Letting your eyes wander to the left of Jupiter in our current evening sky takes you to a couple of constellations that serve as appropriate harbingers to the autumn season and the rains associated with it. The first constellation to encounter is Capricornus, commonly called Capricorn.

One of the summer’s dimmer constellations, Capricorn’s pattern is difficult to mesh with the label — as that of a sea-goat, a lovely amalgam of a goat head and fish tail, with each half meeting at the center of the body. There are a number of tales that tell of this creature and its creation. Other legends describe Capricorn, variously, as Neptune’s offspring, an ocean storm and a rain bearer.

Explanations aside, Capricorn appears as a large triangle above the south horizon. Some observers liken Capricorn to a kite or sail for our summer sky. Two of its brightest stars appear at the northeast corner. The first, Secunda Giedi, is a relatively bright naked-eye optical double. Unlike a binary star, optical doubles are coincidental pairing of stars that appear quite close to each other in our perspective while in reality they’re quite far apart. One of Secunda Giedi’s stars, a giant with roughly the same color as the sun, is about 100 light-years away with the other (a G-type supergiant) almost 700 light-years distant.

Just below is Dabih; a fine, wide binary star that reveals colors very well, even in a binocular view. These stars are about a sixth of a light-year apart, which means you could fit roughly 118 of our solar systems in between these stars. The brighter is actually a trio of stars dominated in brightness by an orange giant.

Off at Capricorn’s other end is Deneb Algedi, the “Tail of the Goat.” From a distance of 50 light-years, this is a system of four stars combining to produce roughly 25 times the sun’s luminosity. Two of these stars combine to produce an eclipsing binary. They’ll eclipse each other regularly over a period of slightly over a day, albeit with a very small fluctuation in brightness.

Above Capricornus is Aquarius. As the name suggests, Aquarius has long been associated as a water carrier of one sort or another by several cultures. Babylonian stones depicted Aquarius as a man or boy figure pouring water from a vessel, while the Arabians represented it as a mule carrying two water barrels.

The first bright star to encounter in Aquarius is Al Bali, with a name that derived from a longer title meaning the “Good Fortune of the Swallower.” How the star obtained this peculiar name is unclear. One suggestion stems from the geometry of Al Bali and its neighboring star in Aquarius compared to their counterparts (Secunda Giedi and Dabih) in Capricornus. As the former appears to be more open than Capricornus’ “mouth” stars, the idea is that Aquarius’ mouth swallows the light of its fellow constellation.

Just to Al Bali’s east is Sadalsuud, which has a name of significance to agricultural seasons. Sadalsuud roughly translates as “Luckiest of the Lucky,” a result of it rising with the sun (which passes close to it through the ecliptical path) at the ending of winter, marking the onset of steady, gentle rains. Sadalsuud’s moderate brightness belies the remarkable properties of this star. More than 600 light-years distant, this yellow supergiant star approaches 2,000 times the sun’s brightness.

Presumably watching the cosmic water action from afar is another constellation; Aquila, the Eagle. Two stars, Lambda and Theta, are the first bright stars in Aquila as you make your way north from Capricornus and Aquarius.

When studying Lambda Aquarius with a spectroscope, astronomers noticed something odd with its spectral line readings. These readings, which help identify elements that compose a star, are generally straight and cleanly delineated from other lines. Lambda’s spectral lines, however, appear blurry, suggesting that this star has a very rapid rotation that distorts spectroscope readings, owing to the Doppler effect and its subsequent shifting of spectral lines. This is a good region for binocular views; Scutum’s Great Star Cloud lies just to Lambda’s northeast and a very red variable V Aquilae is about a degree to the southwest.

Theta Aquila, about 325 light-years away, is twice as distant as Lambda. Appearing as one star, spectroscope studies discovered Theta to actually be a binary, making one full orbit within a period just over 17 days. Doing the math indicates that only 15 million miles separate these stars. Put Theta in our solar system, with the brighter star in the place of our sun, and we’d find that Theta’s second star would be within half the distance to the sun that the planet Mercury is at.

Star party coming soon

If the sky is clear, Heart of the Valley Astronomers will set up our scopes by the baseball field at Adair County Park on Saturday. StarGazing starts at 8 p.m. and is a free, family-oriented event. More information on this event, and others, is posted on our website, www.hvaastronomy.com.