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THE NIGHT SKY

I came outside to say goodbye to the Daystar and hello to the stars and the Moon. Overhead, Polaris conducts the celestial march across the Night Sky. The Big Dipper pours stars into the Milky Way. Aquarius stands to protest Cancer, and Orion points his sword at Sirius and Procyon. Their barking causes Scorpio to sweep its tail across the horizon. I hear an owl asks Who? Who? and my answer is to be humbled by the Mystery of the Cosmos and my place in its Grand Scheme.

The stars put on the same old twinkle, twinkle every night, but She removes her velvet wrap curve by curve, then stands in the spotlight iridescent and nude—her soft cheeks cratered with scars where critics tossed hard things at her. Her face summons wolves and lovers but shows her dark, private face to only me. Tonight, like every night, She'll follow me home, drifting quietly through the trees with her beguiling, big-eyed glow lighting my way and inspiring my dreams.

Twinkle twinkle little star.... how I wonder what you are.
Up above the world so high.... like a diamond in the sky.

If you're anything like me, you rarely go outside after the sun goes down, and if you do, it's to drive somewhere in your car, not to look up at the stars in the sky. But if you do, it's to discover the enchanting mystery of the Cosmos. And spending time under the stars can teach you patience and humility. Patience because it takes time to learn what there is to see and to acquire the skills required to find objects in the sky. Humility because the vastness of space and the wonders of the universe can deepen your connection with the Cosmos. Few things are as awe-inspiring as gazing at the seemingly infinite array of stars overhead, and there are many ways to discover what you can see and where and when to look...

Star Charts at websites like Sky and Telescope and Time and Date
Smartphone Apps like Star Walk and Sky Safari
Videos like Five Things at Youtube.

But a more technical understanding of how the location of a celestial object is defined will give you a deeper appreciation for what you are looking at, whether you use a phone App, a Star Chart or a Video.

THE CELESTIAL SPHERE

Think of the celestial sphere as a giant beach ball with the Earth at its center and the stars embedded on its inner surface as if they are all at the same distance from Earth. We know that isn't true, but the distance an object is from Earth isn't relative to its vertical and horizontal location on the imaginary ball, both of which are given in degrees. Now think of the Earth's equator projected on to the celestial sphere so that Latitude and Longitude on Earth are Declination and Right Ascension in the sky.

       

So the declination and right ascension of a celestial object defines its location on the celestial sphere. That position does not change, but your location on Earth does change because Earth orbits the Sun and rotates on its axis. That means you must know the coordinates of where you live and when the coordinates of a celestial object are in the sky on the night you go outside to gaze at the stars. But the celestial sphere doesn't tell us how to find that information, nor how to apply it to the night sky where we live. So let's explore ways to locate stars and constellations in the night sky.

STAR LOCATION DIAGRAMS

You can buy a telescope with a built-in computer and drive motor that will point the scope to any celestial object at the push of a button. If you don't want to spend the $$ to purchase an expensive telescope, you can use a diagram like the one below to locate a star or a constellation without its declination and right ascension. Start with Polaris and follow the green lines.

THE PLANISPHERE

Another inexpensive way to locate a celestial object without knowing its declination and right ascension is a planisphere designed for the latitiude where you live. Amazon sells the Guide to the Star planisphere and The Night Sky planisphere. The celestial sphere is just an imaginary way to think about celestial objects in relation to the Earth, but a planisphere is a tool to locate celestial objects in the sky where you live by visually answering the where and when questions of star gazing.

Where will the object be East or West of True North? (Azimuth
Where will the object be above my horizon? (Altitude)
When can I see the object? (Month/Day/Hour)

A planisphere answers these questions by visually depicting what the sky looks like on the night you go outside to find a celestial object. If its midnight in early May, for example, and you face North, you'd see the Big Dipper and Polaris.

Below is what the Guide to the Stars planisphere will show you.

In the northern sky, Polaris appears in the same position, regardless of your position on Earth or when you go outside to gaze at the stars. That's because the axis of the Earth points directly at the Pole Star. That's why the sky turns around Polaris, why it's always at the center of a planisphere, and why you can always use Polaris to find the direction north. The North Star not only points you toward the north, but its height in the northern sky also matches your latitude on earth. If you are sailing the Caribbean at 16 degrees north latitude, the north star will be about 16 degrees high in your sky. If you are in southern California at 44 degrees north latitude, the North Star will be about 44 degrees high in your northern sky.

So altitude is in degrees of latitude but you may have noticed that azimuth on a planisphere is in hours, not degrees. On Earth, the Greenwich Observatory is zero degrees for longitude—the horizontal position around the equator. But there is no Greenwich Observatory in the sky, so astronomers use the Vernal Equinox as zero degrees of right ascension—the time when the ecliptic crosses the celestial equator from the southern to the northern hemisphere. This Ecliptic Video will help you visualize the ecliptic in relation to the Vernal Equinox and azimuth on planispheres.

TELESCOPES

Binoculars will help you see the Moon's craters, Jupiter's moons, and Mars. But a telescope will allow you to see many more night sky objects, as well as stunning planetary features like Saturn's rings and Jupiter's stripes. Video #1 will show you five things you can see with a beginning telescope. Video #2 will help you understand the difference between one kind of telescope and another. Then click the links below to see three telescopes recommended for beginners.

Celestron's Inspire

Orion's Star Blast ••• ••• Sky Watcher's Dobsonian

OUR MOON

Around 4 billion years ago, a small planet named Thea collided with the Earth. The collision caused a small section to break off and form the moon. If Thea had missed Earth, our moon would not be here. Planets without moons wobble on their axis. The gravitational pull between the moon and Earth reduces wobble, and that produces a more stable climate than if the moon were not orbiting Earth.

Our moon is often the brightest object in the night sky. Sometimes it's so bright we can see it during the day. Like the planets and the Sun, it rises in the east and sets in the west, and its surface has many features to explore with your naked eye, bioculars or a small telescope—mountains and valleys, craters, and large, dark regions called marias that look like seas from a distance but are probably solidified molten rock. Below are some of the more prominent features.

THE CONSTELLATIONS

There are 88 constellations in the Night Sky, but the twelve constellations of the Zodiac are the most well known and the easiest to find. The diagram below shows why. The twelve Zodiac Constellations can always be found on or near the ecliptic—the apparent path of the Sun as seen from the orbiting Earth. I included the next diagram in case you decide to buy a telescope with a computer. Did you notice that there are actually 13 constellations of the Zodiac? Are you going to find out why?

The diagrams below illustrate how the imagination of the early astronomers conjured up mythical people and animals in the stars to represent their gods and goddesses. The Greeks, for example, saw Orion holding the head of a lion is his outstretched hand—supposedly decapitated with his sword? You can explore the fact and fiction of all 88 constellations with Flash Cards...

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THE STARS

The early astronomers assumed that the stars of a constellation were an equal distance from Earth. They are close enough to make a picture but are actually at very different distances from Earth. The stars of the Big Dipper are a good example. Another aspect of the distance a star is from Earth is that stars are many light years from Earth. The light you see from Polaris took more than 300 light years to reach your eye. The light from our Sun, the Day Star, only takes 8 minutes to reach Earth. The ten brightest stars are evidence that brightness is not a measure of distance from Earth.

Sirius is 8.6 light years from Earth and located in Canus Major
Canopus is 74 light years from Earth and located in Carina
Rigil Kentaurus is 4.3 light years from Earth and located in Centaurus
Arcturus is 34 light years from Earth and located in Bootes
Vega is 25 light years from Earth and located in Lyra
Capella is 41 light years from Earth and located in Auriga
Rigel is 1400 light years from Earth and located in Orion
Procyon is 11.4 light years from Earth and located in Canis Minor
Achernar is 69 light years from Earth and located in Eridanus
Betelgeuse is 1400 light years from Earth and located in Orion

THE PLANETS

Ancient astronomers noticed several bright, star-like lights that moved gradually through the sky against the background of stars. They called these lights planets, the Greek word for wanderers. The planets travel through the constellations along a path in the sky called the elliptic, an imaginary line that traces the path of the Sun through the sky. And, like the Sun, they rise in the east and set in the west.

The names of the naked eye planets are reflected in the names of the days of the week. Saturday, Sunday and Monday are named after Saturn, the Sun and the Moon—Old English adaptations of the Roman names Saturnus, Sol and Luna. The remaining days of the week were named after the Anglo-Saxon and Norse equivalents of the Roman gods Mars, Mercurius, Jupiter and Venus—namely Tiw's Day (after the Old English version of Týr, the Norse God of War), Woden's Day (after the Anglo-Saxon version of Odin, the Norse God of Wisdom), Thor's Day (after the Norse God of Thunder) and Friga's Day (after Freyja, the Norse Goddess of Love and Beauty).

Unlike stars, which generate their own light, planets reflect sunlight into space. Stars are so distant they appear as points of light, but the five brightests planets—Mercury, Venus, Mars, Jupiter and Saturn—are close enough to form a small disk in the night sky, and they can be seen with the naked eye if you know when and where to look. Brightness depends upon on the planet's distance from the Sun, its apparent size and its position in its orbit relative to Earth's position in its orbit. You won't be able to see all of the planets on a single night, but they are visible most of the year except when they are too close to the Sun.

MERCURY ☿

Mercury is the Messenger of the Gods. Its astrological symbol is a depiction of the god's head. Mercury is more difficult to spot than the other bright planets because it never appears very far from the Sun. For northern hemisphere observers, Mercury is best seen on March-April evenings and September-October mornings.

SATURN ♄

Saturn is the God of Agriculture. Its astrological symbol is a depiction of the sickle of the Greek god Kronus. Saturn appears pale yellow to the naked eye. Although never appearing as bright as the other naked eye planets, it outshines all of the stars except Sirius. Saturn is best seen in the morning from April to August and in the evening from October to January.

JUPITER ♃

Jupiter is the King of the Gods (Zeus). Its astronomical symbol is the hieroglyph of the eagle, Jove's bird. Like Venus, it can be seen in twilight and always shines brighter than Sirius. Good quality binoculars or a small telescope will show Jupiter as a small white disk, but it takes a large telescope to see Jupiter's Great Red Spot and its four moons.

VENUS ♀

Venus is the Goddess of Love. Its astrological symbol depicts the hand mirror of the Greek goddess Aphrodite. It also represents the symbol for females. Venus is the easiest planet to see with the naked eye. It shines with a brilliant white or slightly bluish tint. It is the brightest planet in the night sky—only the Sun and the Moon are brighter. Venus has a cycle of alternating morning and evening appearances, and is popularly named The Morning Star and The Evening Star. With a telescope, Venus shows phases much like the Moon

EARTH

Earth is the goddess Gaea, the Mother of all life. Its symbol is a globe bisected by meridian lines for the North, South, East and West points on a compass. If you were on the Moon or a rocket to the moon, Earth might look something like... THIS

MARS ♂

Mars is the God of War. Its astrological symbol depicts the shield and spear of Pyroeis, the Greek god of fire. It also represents the symbol for males. The Red Planet rarely appears red to the naked eye. It varies from pale orange-yellow to orange-red. The reddish colour is caused by iron oxide on the planet's surface. Mars outshines Sirius through a telescope. Despite being close to Earth, It's difficult to see because it's only half the size of Earth. With a small telescope and good atmospheric conditions, you can see its polar caps and the bluish-grey lines which some astronomers thought were canals.

CAMPFIRES IN THE SKY

You now know that the night sky is full of things to see, and that a planisphere can help you find them. So let's pretend that you and your friends have found Sirius and are sitting around a campfire enjoying each other's company and the joy of searching the sky for stars, constellations and planets. Someone says stars are like campfires in the sky and wants all of you to imagine a planet like Earth orbiting Sirius with a group of like-minded friends sitting around their campfire looking down at yours. Indulge your imagination—let it carry you and your friends to once upon a time in a place long ago and light years away.