Naked-Eye Marathon

On Saturday, March 28, at 8:30 p.m. local time (wherever you live), you are invited by the Earth Hour organizers to turn off all your (non-essential) lights for one hour. In addition to the global energy savings and the sociopolitical statement about saving the planet, there’s a less heralded benefit to be derived from this action: a darker environment for stargazing!

If your neighborhood is a darker place during Earth Hour, why not run a marathon— around the sky with your eyes? On that evening, many amateur astronomers will be doing just that, since New Moon weekends in March and April are prime times for the Messier Marathon.

The Messier Marathon (pronounced MESS-ee-yay) is part celestial scavenger hunt, part athletic endurance event. During a Marathon, amateurs attempt to observe all 110 objects in the Messier catalog in one night, using binoculars and telescopes. The catalog is the compilation of the famed 18th century French astronomer Charles Messier, and it has become a staple of amateur astronomy. Because of where the Messier objects are located in the sky, the Marathon is only do-able in March and April. It’s an all-night affair, as some objects must be grabbed right after sunset and some right before sunrise.

Amateur astronomers prepare for a Messier Marathon

What I propose for Earth Hour is not so daunting. Instead, I invite you to try to spot as many of the naked-eye items on the following list you can. No equipment required, except of course your eyeballs. If Earth Hour is clouded over at your location, try it another evening this week. Give yourself one hour only. Don’t forget to dark adapt.

Start by facing west. 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. If you face it, to your back will be east, to your right will be north, and to your left will be south.

To print out a star map for March to aid you in your scavenger hunt, visit Sky Maps. Good luck!

1) The crescent Moon
If you have an obstructed view of the western horizon, look WNW just over the horizon and try to spot the seven-percent-illuminated waxing (growing) crescent.

2) Pleiades
Above the Moon, about two fist-widths away, is the fuzzy patch also known as the Seven Sisters. This star cluster has been known since antiquity.

3) Hyades and the Bull’s Eye
Left, or south, of the Pleiades are the V-shaped star cluster of the Hyades and the brilliant reddish star Aldebaran, which marks the eye of Taurus the Bull.

4) Hourglass of Orion and Orion’s Belt
Continuing south, you come to the Hourglass asterism (recognizable star pattern) of Orion the Hunter. Look for the diagonal three-star pattern that cinches the hourglass. This is Orion’s Belt.

5) Sword of Orion and Orion Nebula
Dangling from Orion’s Belt is a three-star pattern called the Sword of Orion. Look at the middle “star” and you’ll actually be looking at a stellar nursery, a star-forming nebula 20,000 times the size of our solar system! It looks like a star with the naked eye because of its distance.

6) Segment
Starting again at the Pleiades, go right or north to reach the curved six-star asterism that forms the “backbone” of the constellation Perseus. It is known as the Segment.

7) Lazy W
Continue north from the Segment to reach the distinctive W-shaped asterism of Cassiopeia the Queen.

8) Pentagon and the Kids
Continuing above, or east of, the Pleiades, look for the Pentagon asterism of Auriga the Charioteer. Just under Capella, the brightest star in the Pentagon, is a small triangle of stars. This is the asterism known as the Kids.

9) Dog Star
Now face south. Below and to the left of the Hourglass of Orion is the brightest star in the night sky, as seen from Earth. This is Sirius, also known as the Dog Star. It is in the constellation Canis Major the Big Dog.

10) Winter Triangle
Draw a line between Betelgeuse, the brilliant red star at the upper left of the Hourglass and Sirius the Dog Star. Now look for the third point of the equilateral triangle northeast of Sirius. This is the star Procyon in the constellation Canis Minor the Little Dog.

11) Twins
Continuing north from Procyon about the width of two fists, you’ll come to two bright stars that are close together. These are Castor and Pollux, the Gemini Twins. Pollux is the brighter of the two.

12) Beehive
Triangulate eastward from Pollux and Procyon and look for a fuzzy patch. This is the famous Beehive, a star cluster in the constellation Cancer the Crab. It is also known as Messier 44 or M44.

13) Sickle and the Lion’s Heart
Continuing east from the Beehive, look for an asterism shaped like a backwards question mark. This is the Sickle, or the head of Leo the Lion. The bright star at the bottom of the question mark is Regulus, the star that marks the Lion’s heart.

14) Saturn
Now face east. Below Regulus is a bright golden “star.” This is the ringed planet Saturn, one of five planets that can be seen with the naked eye.

15) Spica
Continuing below Saturn in an eastward direction, look for a very bright star low over the horizon. This is Spica, the brightest star in the constellation Virgo the Maiden. The name Spica comes from the Greek word for ear of grain. The figure of Virgo is associated with the harvest and is often depicted carrying an ear of grain.

16) Berenice’s Hair
To the left and a bit below (northeast of) Saturn, look for a large spangly patch. This is the star cluster known as Berenice’s Hair or the Coma Star Cluster. It has been known since antiquity.

17) Big Dipper
Now face north. Look east of the meridian for the distinctive seven-star asterism known as the Big Dipper. It lies in the constellation of Ursa Major the Big Bear. It will be upside down, pouring its contents toward the northern horizon.

18) Arcturus
Follow the curving handle of the Big Dipper eastward to the next bright star. This is orange Arcturus. It name means guardian of the bear, as it appears to follow Ursa Major around the sky.

19) Horse and Rider
Look closely at the middle star in the three-star handle of the Big Dipper. If you have good eyesight, you should see two stars. Bright Mizar and dim Alcor are reported to have been used by the Romans and the Arabs as a vision test. This pair is commonly known as the Horse and Rider.

20) North Star and true north
Draw an imaginary line between the two end stars in the Big Dipper’s bowl--the ones that are farthest from the handle end. These are known as the “Pointer Stars,“ because they point the way to the North Star. Extend that line about five times its length. The first fairly bright star you come to is Polaris, the North Star. It’s slightly dimmer than the end pointer star.

Beginning stargazers are often surprised to learn that the North Star isn’t one of the brightest stars in the sky. Its importance to us is its location, not its magnitude of brightness. Now that you’ve found Polaris, face it square and you will be facing geographic north, also known as true north.

Astronomy Essential: The Sun does not rise or set.

Say what? That’s right, you heard me. The ancient, Earth-centered concepts of sunrise and sunset are cemented into our language. But the Sun doesn’t actually rise or set, except in an Earth-centered universe. And we are modern people and therefore know that the Earth is not the center of the universe.

We do know, however, that the Earth spins on its axis 24/7. We spin toward the east, and so the Sun appears to “rise” over our eastern horizon and “set” on our western horizon. The Sun’s apparent motion, or the way it appears to move in our sky, is from east to west. However, in the Sun-Earth system, it is planet Earth that is moving, not the Sun.

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.

Follow the Drinking Gourd

Two weeks ago, we used the most famous star pattern in the night sky to locate an exceptional deep-sky object that lies outside our Milky Way galaxy. This week, let’s return to our galactic ‘hood and take a closer look at the notable star pattern we call the Big Dipper.

Known to every child in the Northern Hemisphere, the Big Dipper may be the most ancient of all star patterns recognized and recorded by humans. The Big Dipper is not a constellation, as many believe. The Big Dipper is the central asterism (recognizable star pattern) in the constellation Ursa Major, the Great Bear.

Ursa Major is a circumpolar constellation. In the Northern Hemisphere, a circumpolar constellation is one that circles 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. That imaginary point just happens to be extremely close to the star Polaris, which is why we call Polaris the North Star. We can use the Big Dipper to locate the North Star and geographic north; more on that in a minute.

Diagram of celestial poles by Dr. Guy Worthey

For skywatchers in latitudes above 35 degrees north, circumpolar constellations never set; they are always above the horizon as they endlessly circle the North Star counterclockwise, making one revolution per day. But although we commonly say they are "circling," constellations like Ursa Major are not really moving around the Pole. Their apparent motion--or the way they appear to move in our sky--is actually caused by our rotation, as planet Earth reliably spins 24/7 on its axis.

The Big Dipper’s proximity to the North Star has made it a favorite of travelers and navigators throughout history--a reliable guide in the night sky when plotting one’s course across land, water, or air. Let’s get oriented, shall we?

1) You’ll need to face north, so 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 left shoulder to the west, and you’ll be facing approximately north.

2) Wait at least one hour after sunset to begin observing, so that twilight’s over and your sky’s good and dark. A waxing (growing) crescent moon will be in the western sky after sunset through the weekend. First Quarter Moon, when the Moon’s face is half illuminated, occurs on Tuesday, June 10. The earlier in this observing week you look at the Dipper, the less interference you’ll have from moonlight. Or, if you’re a night owl, you can simply wait until the Moon sets.

3) Facing north, look for a distinctive seven-star asterism that looks like a giant, long-handled saucepan. It will be due north to a little west of north and somewhere between the zenith, the point directly above your head, and the northern horizon. The saucepan will be oriented upside-down. Found it? Great. This is the famous Big Dipper (water dipper), or as the French call it, “La Casserole” (saucepan).

Chart created with Your Sky

4) All seven stars of the Dipper are bright enough to be seen even in urban areas that are somewhat light polluted. In a future post, we’ll take a closer look at the individual stars.

5) Make a point of looking at the Big Dipper early in the evening and noting its orientation. Then look at it again before you turn in for the evening, or if you get up before sunrise, look at it again before dawn lights the sky. Do you see how its orientation has changed, how it has rotated counterclockwise and is approaching right-side-up? It’s exciting when you first realize how the stars above the North Pole will 'move' in a predictable, circular motion every night of the year, simply because we live on a spinning globe.

They are all ‘moving’ around the North Star. You can locate Polaris using the two stars on the right side of the right-side-up Dipper’s bowl. These two stars are called the pointer stars, because they point the way to Polaris.

Chart created with Your Sky

6) Draw an imaginary line connecting the two pointer stars. Then extend that line about five times its length, above the right-side-up Dipper. The first fairly bright star you come to is Polaris; it’s slightly dimmer than the top pointer star. Beginning stargazers are often surprised to learn that the North Star isn’t one of the brightest stars in the sky. Its importance to us is its location, not its magnitude of brightness. Now that you’ve found Polaris, face it square and you will be facing geographic north, also known as true north.

Our ability to recognize the Big Dipper enables us to reliably find north at night--without a compass, a map, location familiarity, or knowledge of where the sun set earlier. This is a celestial landmark that might even spell the difference between life and death, or captivity and freedom. According to American folklore, runaway slaves traveling under cover of night oriented to the Big Dipper and followed it north to freedom. They called it the “Drinking Gourd,” a reference to the hollowed-out gourd used in rural areas as a water dipper.

A hauntingly beautiful folk song of uncertain origin called “Follow the Drinking Gourd” may have been used by the Underground Railroad to provide coded directions in its lyrics, guiding the slaves to freedom. Click here to play an MP3 of “Follow the Drinking Gourd,” courtesy of Roger McGuinn’s Folk Den.

When the sun comes back and the first quail calls,
Follow the Drinking Gourd.
For the old man's waiting for to carry you to freedom,
If you follow the Drinking Gourd.

Reward notice for runaway slaves Harriet Tubman and her brothers