Milky Way

Steps for your Night Sky Tour

First, to orient yourself, download the August Evening Sky Map by clicking here.

You will want to have the direction that you are facing at the bottom of the map.

Find a location away from streetlights and as open to the horizons as possible.

To read the sky map, avoid using a white light flashlight or your phone’s light.  The bright light will dazzle your eyes and prevent your eyes from becoming adapted to the dark. 

If you have it, use red cellophane to cover your flashlight lens so the map is just barely legible.  Don’t worry, your eyes will adapt to the darkness. When your eyes are dark adapted you will be able to see fainter stars and the shapes of the constellations will match those on the Sky Map much better.

This Night Sky Tour is best started around 8:30 p.m. Eastern Standard Time.

Find North

In order to begin your tour, we first have to face north and then turn the map so north is at the bottom of sky map when we hold it in front of us.

On the Cape it’s fairly easy to find north at night.  One way to find north is to think about where Nantucket Sound is—which is on the southside of the Cape —so to face in a general northerly direction simply turn so the Sound is at your back.

Now let’s find the North Star, Polaris, the star that in the Northern Hemisphere is always aligned with true North.

Ursa Major and North Star

The Big Dipper and Ursa Major

As you look up in the northern night sky you will see a very bright pattern of seven stars that looks like an old-fashion water ladle.  This is called The Big Dipper. These will be the brightest group of stars in the northwest above the northern horizon.

Use the Sky Map to judge how high these stars are in the sky.  Turn the Sky Map so the direction North is at the bottom of the map. Now locate the Big Dipper on the map at approximately the 7:00 position. Once you find this group of stars on the map, then you will be able to move around the sky using the map very easily. At this time of year, the Dipper appears to be pointed down towards the horizon, with the ladle part of the Dipper nearest the horizon. The Big Dipper is part of a larger constellation call Ursa Major (The Big Bear).  The Dipper part of the constellation represents the Bear’s midriff and hindquarters and its legs extend from the bottom of the cup part of the dipper.  Its feet are marked by three pairs of fainter stars.  The bear’s forequarters extend beyond the front of the dipper.

To find the North Star draw a line between the two stars at the end of the ladle and then extend it about five times that length.  The only bright star in the sky where that ends is the North Star.  It is not the brightest star, but it is always in that location very close to the North Celestial Pole. The Sky Map shows which two stars to use.

Make sure you take the time to correctly identify the North Star.  A little practice and it will pop out from the night sky.  Be sure too to locate it on the map.

Ursa Minor (The Little Bear)

The North Star is in another constellation called Ursa Minor (The Little Bear) and it’s also called the Little Dipper.  It is much fainter than the Big Dipper and the shape isn’t as obvious as the Big Dipper, but if you are in a dark location you should be able to see it. Locate it on the map and then locate it in the sky, curving up towards the Big Dipper. A pair of brighter stars between the North Star and the Big Dipper known as The Guardians are in the ladle part of the Little Dipper.

Ursa Major and Minor are referred to as Circumpolar Constellations because they always circle the North Star and never set.  While the North Star appears to never move, all other stars seem to circle around it, sometimes above, sometimes below and to the right or left.

Cassiopeia

Cassiopeia

An easy circumpolar constellation to locate is Cassiopeia.  A group of 5-6 stars in the 3 o’clock position from the North Star looks like the letters “M” or “W” tuned on their side.  This is the constellation Cassiopeia which represents the mother of Andromeda.

Cepheus

At about the 1 o’clock position from the North Star, right above Cassiopeia, is the constellation Cepheus. Look for a fainter group of stars in the shape of a pentagon, a square with a triangle on top it leaning to the left.  This constellation represents the father of Cepheus and the husband of Cassiopeia. 

In about two months the other constellations associated with these two constellations will be visible in the early evening and the entire myth can be more easily told.

The Sky Overhead

Turn the Sky map 90 degrees so the direction marked East is at the bottom of the page and turn yourself 90 degrees as well.  Now you are facing east.

Move your neck so you are looking almost straight up.  You will see three very bright stars. These form an asterism called the Summer Triangle, since you can trace a triangle by drawing a line that connects all three stars. This is marked on the map.

Lyra the Lyre

The brightest star in the Summer Triangle is called Vega.  Vega is the brightest star in the small constellation of Lyra the Lyre.  The constellation looks like a very small parallelogram with Vega at one angle of the figure.

The Lyre used to be singer Orpheus’s, but when he died the gods placed it among the stars.

Our solar system, the sun and associated planets, is moving towards space in the general direction of this constellation.

Cygnus the Swan

The second star in the Summer Triangle is called Deneb, located in the 10 o’clock position from Vega.  Deneb is the brightest star in the constellation Cygnus the Swan.  Deneb represents the tail of the swan as it flies across the sky.  A line of 3 stars extends in a fairly straight line towards the south from Deneb below Lyra.  This represents the body of the Swan and its neck and head.  A line of stars that extends from either side of the first star from Deneb represents the bird’s wings.

If you still can’t “see” this figure, try looking for a cross of stars where Deneb represents the head of the cross.  This is a colloquial name for the constellation, the Northern Cross.

Juvenile bald eagle at Bell’s Neck by Sue Swartzlander

Aquila the Eagle

The last star in the Summer Triangle is called Altair.  It is the brightest star in the constellation Aquila the Eagle.  Altair is in the middle of a line of three stars. A group of dim stars towards the south from Altair represents the wings and tail of the Eagle.

The Southern Sky

Now turn the map 90 degrees so that south is at the bottom and turn yourself 90 degrees, too, so you are facing south.

Jupiter and Saturn

If you are correctly oriented, you should see two bright stars near the southern horizon.

The brightest “star” is actually the planet Jupiter and the other bright “star” at the 9 o’clock position from Jupiter is the planet Saturn.

Jupiter is the largest of the planets and takes about 12 years to orbit the sun.  Saturn, which has beautiful rings surrounding it, is the second largest planet.  Saturn takes 29 ½ years to orbit the sun.

Another way to consider the length of time it takes for these two planets to orbit the sun, is to realize that Jupiter will not be in this part of the sky again until 12 years from now in 2032. Saturn will not be in this position again until around 2050.

Sagittarius

Jupiter and Saturn are both in the constellation of Sagittarius. Look at the bright group of stars to the right of Jupiter. These stars form the outline of a teapot: the handle on the left. The spout on the right, and the lid on the top.  The sky map will help you identify it.

Sagittarius represents an archer shooting a bow and arrow.  The handle of the teapot suggesting an arm pulling back the bowstring and the spout suggesting the bow held out by the other arm.

Scorpius

Scorpius

Looking on the right from Sagittarius You should be able to see a bright red star.  This is the star Antares, the brightest star in the constellation of Scorpius the Scorpion.  As the Sky map makes clear, this is a constellation that clearly looks like the animal it is supposed to represent.

Upwards from Antares in the 2 o’clock position is a line of three stars representing the scorpion’s head with its claws conceived as extending out from there.  Tracing an obvious line of stars down from Antares in the 7 o’clock position, you can trace the line of stars of the scorpion’s body and then down and around to its tail with its stinger on the end.

The Summer Milky Way

The Milky Way is what we call the faint band of light that stretches across the sky at this time of year from the southern horizon, to overhead, to the northern horizon. The Milky Way is the combined light of billions upon billions of distant stars in our Galaxy.

To locate the Milky Way, look at the general area of the constellations of Sagittarius and Scorpius.  There is a general haziness about the area—you can see this marked on the map.  The Milky Way may not be obvious near the horizon in the south, but if you simply extend a line back through Aquila, Cygnus, and Lyra overhead, it should become clearly visible overhead.  The Milky Way extends back down towards the north through Cepheus and Cassiopeia.

Moon by Gus Romano

This concludes your self-guided August Night Sky Tour. When social distancing circumstances allow, we look forward to hosting these celestial events in person again. Until then, we’ll offer these astronomy opportunities and hope you enjoy the rest of your summer.