Astronomy enthusiast tells story of constellations

MARENGO — Mark A. Bowman, a retired professor and astronomy enthusiast, shared his knowledge of constellations with a small audience at Marengo Public Library Jan. 22.

Anyone who missed it can catch a stargazing workshop presented by Bowman and Kate Poelter at Williamsburg Public Library Saturday, Feb. 8, at 1:30 p.m.

Most stars are not bright like the Star of Bethlehem, said Bowman. “Mostly they’re just little bright dots in the sky.”

Constellations are groups of stars that “appear” to be shapes, said Bowman. They are optical illusions. They appear to be at the same distance because of the angle at which we see them.

In the Orion constellation, one star is 243 light-years away and another is more than five times that distance, Bowman said.

The constellations would not have the same shapes if we saw them from a different angle.

“Constellations are exquisitely old,” said Bowman. They date back to the neo-ice age.

The Sumerians created pictures in the stars, the Greeks added their mythology and the Romans changed the names to Latin, though some names reflect Arab origins, Bowman said.

Greco-Roman astronomer Ptolemy listed 48 constellations. Today the International Astronomical Union recognizes 88 constellations.

Asterisms

Asterisms are also pictures in the sky formed by star groups. They were considered constellations until modern astronomers named 88 official constellations, Bowman said.

Like constellations, asterisms are useful for navigating the night sky. The teapot within Sagittarius leads us to the Milky Way, which appears to be steam coming out of the teapot.

The Big Dipper, one of the most well-known asterisms, is within Ursa Major. It’s exceptionally bright and resembles its name.

The Big Dipper points to Polaris within the Little Dipper, and the arc of the handle leads the eye to Arcturus, the ox driver pulling the plow that is the Big Dipper.

Orion’s belt helps us recognize Orion, said Bowman. It points leftward toward Sirius in Canis Major and to the right at Aldebaran in Taurus.

Some asterisms link constellations. The Summer Triangle of Vega, Altar and Deneb connects Lyra, Aquila and Cygnus.

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Seeing pictures

It takes a great imagination to see the pictures in the constellations, Bowman said. They are supposed to resemble their names, but sometimes the association is a stretch.

Leo looks like a male lion lying with his head raised, if you see the constellation facing right. If you view the constellation as facing left, it looks more like a mouse with its tail raised, said Bowman.

The Gemini twins are relatively faint in the sky. They look like stick figures with their brightest stars, Castor and Pollux, representing their heads and giving them their names.

Every primitive culture was interested in the stars, and they could see them better than modern stargazers because they didn’t have the light noise we have, said Bowman.

Telling stories

Ancient people believed the stars influenced their lives. They believed in many gods. Many constellations represent these gods and have elaborate stories to accompany them, Bowman said.

Cassiopea, for example, is named for the queen of Ethiopia who claimed to be more beautiful than the Nereids. That angered the god Poseidon. He sent a sea monster, Cetus, represented by a constellation, to ravage Ethiopia.

Cepheus, the king of Ethiopia, represented by another fall constellation, was told by an oracle to sacrifice his daughter to the sea monster, so Cepheus chained Princess Andromeda to a rock for Cetus to find.

The constellation Andromeda includes the Andromeda Galaxy. American astronomer Edwin Hubble discovered the Andromeda Galaxy in 1923.

Mythology says that Perseus, a demigod, rescued Andromeda and killed Cetus.

The ancients

The most ancient constellations are those of the Zodiac, Bowman said.

Taurus was important in the late stone age when glaciers were retreating in Europe and cave people were hunting mammoths with spears, though they were most likely hunting the aurochs, the predecessor to our domestic cows, said Bowman.

A cave painting in the Lascaux caves in France is believed to show the constellation and the Pleiades star cluster.

Stellarium

Anyone who wants to learn more about stars and constellations should try Stellarium Astronomy Software, said Bowman.

The free software, created in 2000 by Fabien Chereaux, represents the brightness of stars by the sizes of the circles representing them. It links the stars that form constellations.

Toggling icons along the bottom of the screen will produce the names of stars and constellations.

“This is how I learned them,” said Bowman.

Stellarium will also show locations of planets. “Mars has been orangey beautiful for weeks now,” said Bowman.

The locations of satellites and the International Space Station can be found using Stellarium.

Choose a date and location in Stellarium and the software will display what the night sky looked like or will look like at that time and place.

Stellarium is a fantastic learning tool, Bowman said.

Bowman also suggested using Skymaps.com to see where the constellations will be in the local sky each month.

Seeing the stars

“You see constellations best when you’re looking directly above,” said Bowman. There’s less atmosphere to look through. That’s why observatories are placed in the desert.

The best telescopes are satellite mounted, Bowman said.

It’s also best to look at the skies from the darkest places and during the darkest nights when the moon is new.

“I will travel west this spring and summer,” said Bowman. The darkest place in Iowa is White Rock Conservation Area near Coon Rapids, he said. He was there in November and was able to see many more stars because of the reduction of light noise.

Bowman is a member of the Cedar Amateur Astronomers which meets at the Eastern Iowa Observatory and Learning Center on the grounds of Palisades-Dows Preserve between Mount Vernon and Ely.

The building has four large, mounted telescopes in dedicated buildings and a large auditorium that hosts monthly public events.

Cedar Amateur Astronomers members meet monthly, but non-members are welcome, Bowman said.

Bowman’s program in Marengo was presented by Friends of the Marengo Public Library.