A bright planet is always an opportunity. You can jump on one and go for a ride. The fact that they move across the sky sets them apart from the stars, which barely budge even over many human generations. Mars is now the most prominent of the evening planets and shines high and bright in the southwestern sky at nightfall. Nestled among the constellations most prominent in autumn, you can't miss it.

In mid-January, the petite constellations Aries and Triangulum are located directly above Mars and centered between the Pleiades star cluster (Seven Sisters) and the bright asterism called the Great Square. (Stellarium)
In mid-January, the petite constellations Aries and Triangulum are located directly above Mars and centered between the Pleiades star cluster (Seven Sisters) and the bright asterism called the Great Square. (Stellarium)

Last October when it was closest to the Earth Mars beamed from Pisces the Fish, a large, faint figure virtually invisible from cities and suburbs. Since then the planet has moved east as it orbits the sun. January finds it in the small, zodiac constellation Aries the Ram. Comprised of three stars, Aries looks like bent index finger pointing at Mars.

In this closer view I've labeled important reference stars in each constellation by name. (Stellarium)
In this closer view I've labeled important reference stars in each constellation by name. (Stellarium)

Around 7 p.m. local time, ruddy Mars stands high in the southwestern sky. Look 6° (three fingers held together at arm's length) to the upper right of the planet and you'll see two stars. The brighter one is Sheratan — similar in brightness to the Big Dipper stars — and fainter Mesarthim. Connect them to Hamal, the constellation's brightest star, and bingo —you've just found Aries!

Newsletter signup for email alerts

Despite its small size and modest brightness Aries was an important constellation in ancient times. Back then it was home to the vernal equinox, the point in the sky where the sun crosses the celestial equator moving from south to north, marking the first day of spring.

The mythological figures are depicted for our featured constellations. Aries was no ordinary ram but the one Jason and the Argonauts hunted for its golden fleece. (Stellarium)
The mythological figures are depicted for our featured constellations. Aries was no ordinary ram but the one Jason and the Argonauts hunted for its golden fleece. (Stellarium)

For that reason Aries was considered the start of the zodiac — the band of 12 constellations through which the sun, moon and planets travel — with the spring equinox point designated as the first point in Aries. Because of the slow wobble of Earth's axis called precession that point has since drifted about 30° westward into Pisces. In the year 2597 the equinox will cross from Pisces into Aquarius. Astronomically speaking, we'll be waiting a while before the start of the mythical Age of Aquarius. Because a full wobble takes about 26,000 years, the spring equinox won't return to Aries until about 20,000 A.D.

Now, make a vertical fist at the sky. If you place Sheratan on the bottom, at the top you'll see a skinny triangle of stars called Triangulum the Triangle. Finally, a constellation that looks exactly like its name! Its stars shine weakly at magnitudes 3 and 4, but the group is so compact and easy to find you can hardly miss it. The ancient Greeks knew this isosceles triangle as Deltoton because it resembled the capital letter Delta (Δ).

My favorite comparison comes from Eratosthenes, the ancient Greek astronomer who made the first measurement of the size of the Earth around 240 B.C. He wrote that Triangulum represented the Nile River delta, which indeed it does.

We might have had two side-by-side triangles in the sky, but astronomers weren't keen on it, so the smaller version, Triangulum Minus, fell out of use. You can use the star Mothallah to guide you to the Pinwheel Galaxy, 4.3° to the northwest. (Stellarium)
We might have had two side-by-side triangles in the sky, but astronomers weren't keen on it, so the smaller version, Triangulum Minus, fell out of use. You can use the star Mothallah to guide you to the Pinwheel Galaxy, 4.3° to the northwest. (Stellarium)

If you think Triangulum isn't much of a constellation, check out the obsolete group Triangulum Minus. Polish astronomer Johannes Hevelius introduced this miniature version in 1687 by connecting three faint 5th magnitude stars into a teeny equilateral triangle snugged up against its bigger brother. Naming one group "Minus" meant he had to rename the original constellation Triangulum Majus. Few astronomers adopted the new figure and T. Minus eventually passed into obscurity. But you can still see it today from dark skies with the help of the map above. Were Hevelius still around he'd give you an approving wink.

Both Triangulum and Aries each possess a major deep-sky highlight. In Aries, the faintest star, Mesarthim, is one of the most exquisite double stars in the entire sky for small telescopes. Called an "equal pair" because both stars are nearly equally bright (magnitudes 4.5 and 4.6), the lookalikes are just 7.6 arc-seconds apart. For reference, one arc-minute equals 1/30th the diameter of the full moon, and there are 60 arc-seconds in an arc-minute. Magnified 50-75x the two stars look like a pair of car headlights seen from a distance.

The Pinwheel Galaxy looks fuzzy and diffuse in nearly every instrument, but an 8-inch of larger telescope will reveal its fluffy spiral arms and bright core. Also known as M33 or the Triangulum Galaxy, it about 60,000 light-years across (compared to 100,000 for the Milky Way) and 2.7 million light-years from home. (Frank Barrett)
The Pinwheel Galaxy looks fuzzy and diffuse in nearly every instrument, but an 8-inch of larger telescope will reveal its fluffy spiral arms and bright core. Also known as M33 or the Triangulum Galaxy, it about 60,000 light-years across (compared to 100,000 for the Milky Way) and 2.7 million light-years from home. (Frank Barrett)

If you have access to dark skies and a pair of 50mm binoculars (7x50, 10x50) or larger, look 4.3° — about two-thirds of a typical binocular field of view — to the northwest or upper right of Mothallah, Alpha (α) Trianguli. Play the binoculars around a bit, and you'll detect a faint wad of fuzzy haze. That misty glow is one of the brightest galaxies in the sky, dubbed the Pinwheel and also known by its catalog number M33. At 2.7 million light-years away it's slightly farther from the Earth than the Andromeda Galaxy.

Like both the Milky Way and Andromeda it's a spiral galaxy, but with arms puffy and flocculant with star clouds compared to the others' more streamlined appearance. Visible to the naked eye under pristine skies, M33 was never seen by ancient astronomers probably because it was too faint to notice unless you knew exactly where to look.

On a final note I want to point out a curious coincidence about names. Mars was the Roman god of war which the Greeks knew as Ares. With Ares in Aries this month I wondered if the two were related. They're not. Aries comes from the Latin aires or "ram," which is related to arietare "to butt," while Ares goes back to the Greek are, meaning bane or ruin.

The next time the sky's clear, I hope you'll partner with Mars to make some new constellation friends.

"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.