Kids, More Kids, and Something Fishy

Last week we located the constellation of Auriga the Charioteer and explored its central asterism (recognizable star pattern), the Pentagon.

Now let’s take a closer look and see if we can spot three smaller, quirkier asterisms.

Auriga the Charioteer in Johann Bode’s 1801 star atlas
Courtesy of Linda Hall Library of Science, Engineering and Technology

1) About an hour after sunset, locate the Pentagon. Consult last week’s post if you need help finding it.

The Pentagon of Auriga
Star maps created with Your Sky

2) Just south of bright Capella is a small triangle of stars. This is the asterism known as the Kids, a reference to the two baby goats being cradled by the ancient figure of the Charioteer. The three stars are all dimmer than any of the five stars of the Pentagon.

The brightest of the three is Almaaz, which is Arabic for he-goat. (Do you recall which star in Auriga has a name that means she-goat?) Almaaz is a yellow-white supergiant that undoubtedly will expire someday in a cataclysmic explosion called a supernova.

The other two dimmer stars of the Kids asterism are called the Haedi, Latin for the kids.

Asterisms in Auriga

3) Hoofing it across the Pentagon, south of Menkalinan, look for another small triangle of stars that resembles the Kids, if the Kids were dimmer and upside down. This is the asterism called the Little Kids.

4) Finally, look inside the Pentagon, down toward its “base.” If you’re in a dark location, free of light pollution, you’ll see an elongated patch of light. This is the combined light from a string of four naked-eye stars plus a couple dimmer ones, and this is the asterism known as the Minnow. Can you see the silvery flash of its scales as it navigates the currents of the Milky Way?






Astronomy Essential: Polaris, the North Star, is NOT the brightest star in the night sky.

Many beginning stargazers have trouble picking out Polaris (poe-LAIR-uss) because they figure the North Star must be really bright and flashy. But on the scale of cosmic bling, it’s not much of a sparkler. In fact, it’s number 48 on the brightest-stars hit parade.

The importance of Polaris lies in its location, not its magnitude of brightness. It lies very close to the North Celestial Pole, the imaginary fixed point in the sky that the Earth’s axis would intersect, were it extended from the North Pole into space. Therefore, if you locate Polaris and face it, you’ll be facing geographic north, also known as true north.

To learn how to locate Polaris using the Big Dipper, visit this post.

By the way, the brightest star in the night sky is Sirius, aka the Dog Star, found in the winter constellation of Canis Major, the Big Dog.

The Purloined Pentagon

Just north of Orion the Hunter and the horns of Taurus the Bull lies a distinctive pentagon of stars. You may recall from murky memories of high school geometry that a pentagon is a five-sided closed figure. This starry pattern is an irregular pentagon, since its five sides are not equal in length.

The celestial Pentagon is an asterism (recognizable star pattern) containing the brightest stars in the constellation Auriga the Charioteer (aw-RYE-guh). Let’s take a closer look.

1) About an hour after sunset, face south. If you don’t know the cardinal directions at your location and you don’t have a compass, make note of where the sun sets on the horizon. That spot is approximately west. Stand with your right shoulder to the west, and you’ll be facing approximately south.

Star maps created with Your Sky

2) Locate the Hourglass asterism of Orion, rising in the southeastern sky. Above it are the business ends of Taurus’s deadly horns. Keep going north past them to locate the Pentagon.

3) The brightest star in the Pentagon is a tad brighter than both Betelgeuse and Rigel, the two brightest stars in the Orion hourglass. This is Capella, the sixth brightest star in the entire night sky as seen from Earth. Capella (kuh-PELL-luh) is from the Latin for she-goat. It’s a yellow-white star, only 42 light years away.

4) Next to Capella, moving counterclockwise around the Pentagon, is the second brightest star in Auriga, Menkalinan (menn-KAH-lih-nan). Its name is from the Arabic for shoulder of the rein-holder. Menkalinan is a white star.

5) The second brightest star in the Pentagon is not Menkalinan, and it’s not in Auriga. To make the Pentagon shape, we must purloin a star from Taurus. This star is Elnath, the tip of Taurus’s northern horn. Elnath (EL-noth) is from the Arabic for butting with the horns. Elnath is a blue-white giant star.

We’ll continue our exploration of Auriga in more depth next week. See you then!

Astronomy Essential: There is no dark side of the Moon.

Pink Floyd megahit notwithstanding, there is no such thing. The Moon has no side that is always dark. The entire surface of the Moon is illuminated by the Sun at one time or another during its month-long orbit around the Earth. However, only half of the Moon’s sphere can be illuminated by the Sun at any given time (shine a flashlight at a baseball, and you'll get the idea).

Although the Moon has no dark side, it does have a far side that always faces away from Earth. Because the Moon’s rotation (spin around its axis) is in lockstep with its revolution (orbit around the Earth), the same lunar hemisphere always faces us earthbound viewers.

If you could instead perch on the Sun awhile to observe the Earth/Moon system, you’d watch Moon circling Earth, turning just enough on its axis to keep the same face toward Earth as it went around. And from your vantage point on the Sun, you’d notice that— over the course of a month— your view of the Moon’s surface continually changed until you had seen it all.