ORIGINS OF ASTRONOMY
Before we know more about what we know about the stars and the planets, let's first think of HOW we know about these things. Welcome to the SAMPLE X ACTIVITY!!!
Sample X Activity
Inside this box is a system you are not allowed to open. Your job is to tell me what is inside.
You may observe it! You may measure it! You may experiment on it!
But you may not directly see inside.
Grab a white sheet of paper and divide it in two. Write on the top of each column Observations and Inferences. Don't forget to put your names on it.
You may observe it! You may measure it! You may experiment on it!
But you may not directly see inside.
Grab a white sheet of paper and divide it in two. Write on the top of each column Observations and Inferences. Don't forget to put your names on it.
Observations: What do you see, hear or notice? |
Inferences: What can you deduct from this? |
You have 10 minutes!!!
Can we ever know precisely what is inside the box?
It's exactly the same when we try to understand what is far away from our planet. We get bits and pieces of information; we know ways to measure for some elements, for heat, for light, but we can never really know exactly how these pieces come together when they are so far away. And this is astronomy: the study of far-away, large and very old objects in the sky, using the tools and technology we have at the moment.
A Part of Our Past
The sky is a part of our local environment wherever we live. For many, including First Peoples, knowledge of the observable universe is part of an interconnected world view that includes social, cultural, and spiritual aspects.
This photo of a well-known, huge medicine wheel in Wyoming is one example of how First Peoples connect with their world view. First Nations of the North American plains built hundreds of medicine wheels. Most are in Canada. The largest and oldest, in Alberta, dates back at least 5000 years.
Many align with the Moon, Sun, and stars, and predict events such as solstices and the rising of sky objects at certain times of the year. Because people observe the sky from their local place, there is a great diversity of perspectives about the universe, because the sky will look different from a beach in Brazil when comparing to the sky on a mountain in Vancouver. For one, we would never see the Aurora Borealis!
Many align with the Moon, Sun, and stars, and predict events such as solstices and the rising of sky objects at certain times of the year. Because people observe the sky from their local place, there is a great diversity of perspectives about the universe, because the sky will look different from a beach in Brazil when comparing to the sky on a mountain in Vancouver. For one, we would never see the Aurora Borealis!
Your location changes what you can observe because Earth is a sphere and because different places lie at different latitudes. Someone living far north, such as in Yellowknife, sees a different part of the sky than someone living much farther south, such as in Mexico City or Tucson. Australia sees the Southern Cross; we don't! Some stars visible from one place may never rise above the horizon in another. And the latitude also affects the height of the Sun in the sky, the length of daylight, and the position of certain stars.
And weather also matters. If a place has a lot of rain and is a real thick rainforest, like the middle of the Amazon in Brazil, we will see less stories about stars and more stories about Gods and entities in the jungle, and the Moon is the most used celestial body used by them. People adapt their stories to the things they see and that matter most to them. A place with frequent clouds offers fewer clear viewing nights than a dry desert region, where everything you see is sky. Different communities developed knowledge of the sky based on what is most visible to them.
Long before telescopes, satellites, space probes, or weather apps, people learned about the sky by watching it carefully. For thousands of years, the sky acted as a clock, a calendar, a compass, a weather guide, and a source of stories. People noticed that the Sun followed predictable paths, that the Moon changed shape in a repeating cycle, that stars appeared to move across the sky, and that a few bright objects wandered differently from the rest.
So, the first scientific tool we used to study astronomy was very simple: observation.
As ancient Homo sapiens, we observed and gathered patterns over years, and passed that information to our children, and slowly developed the knowledge we have today by slowly adding more and more tools that made our conclusions about the sky more accurate and meaningful.
So, the first scientific tool we used to study astronomy was very simple: observation.
As ancient Homo sapiens, we observed and gathered patterns over years, and passed that information to our children, and slowly developed the knowledge we have today by slowly adding more and more tools that made our conclusions about the sky more accurate and meaningful.
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The King of the Sky
It is easy to understand why the Sun became associated with life, authority, power, and leadership in many cultures. Nearly every ecosystem on Earth ultimately depends on energy from the Sun.
From Earth, the Sun appears to rise in the east, travel across the sky, and set in the west.
But the Sun is not actually circling Earth every day. This apparent movement happens because Earth rotates from west to east. As Earth turns, the Sun appears to move in the opposite direction across our sky -- it rises on the East and sets on the West, no matter where you are on Earth.
The Sun's path changes throughout the year. During summer, it follows a higher and longer path through the sky; during winter, its path is lower and shorter. This is one reason summer days are longer and winter days are shorter. These changes happen because Earth's axis is tilted. Some places on Earth won't see much of a change; in places close to the Equator, the difference is only a few degrees, and it is warm all year around, even though this shift causes rainy and sunny seasons.
From Earth, the Sun appears to rise in the east, travel across the sky, and set in the west.
But the Sun is not actually circling Earth every day. This apparent movement happens because Earth rotates from west to east. As Earth turns, the Sun appears to move in the opposite direction across our sky -- it rises on the East and sets on the West, no matter where you are on Earth.
The Sun's path changes throughout the year. During summer, it follows a higher and longer path through the sky; during winter, its path is lower and shorter. This is one reason summer days are longer and winter days are shorter. These changes happen because Earth's axis is tilted. Some places on Earth won't see much of a change; in places close to the Equator, the difference is only a few degrees, and it is warm all year around, even though this shift causes rainy and sunny seasons.
For people watching the sky over many years, these repeating and predictable patterns became extremely useful. The position of the Sun could help mark seasons, times for planting and harvesting, the length of the year, and the direction of travel.
So, what would happen if you were 10,000 years ago right here in Vancouver, in a time before modern astronomy? Imagine you were one of the First Peoples of Canada, living way before any Europeans arrived here, looking up during the night, perhaps near a fire to keep warm. Besides the fire, there was no light pollution like we have today, and as the fire died down, the stars looked so bright and close, he felt like he could touch them. There was no NASA, no Google, no internet; just a person and two eyes, looking up at the sky. Some of those celestial bodies came and went, some seemed not to move much at all; some were predictable, and some passed like a flash of light.You would still see the same basic objects we see today: the Sun, the Moon, thousands of stars, five brighter stars that behaved very differently than the rest, the Milky Way, meteors, comets, and occasionally sudden or unusual events in the sky. But you would not know what they were!
But observing them revealed a pattern, and this pattern became information and knowledge. These patterns allowed for predictions which were used to assist our ancestors.
Just like our ancestors, we can predict the behaviour of celestial bodies in the sky.
And from these patterns, we created meaning. Different cultures have developed stories, names, calendars, navigation systems, ceremonies, and teachings connected to the sky.
And of course, the same stars can be grouped into completely different patterns depending on the culture observing them.
For example, the stars that one culture groups into a particular constellation may form a completely different figure in another tradition. The function and origin of these groups of stars or celestial bodies give birth to stories which are passed down generation after generation. These stories are not simply attempts to “explain science.” They also carry history, cultural teachings, relationships to land, navigation knowledge, seasonal information, or spiritual meaning.
And of course, the same stars can be grouped into completely different patterns depending on the culture observing them.
For example, the stars that one culture groups into a particular constellation may form a completely different figure in another tradition. The function and origin of these groups of stars or celestial bodies give birth to stories which are passed down generation after generation. These stories are not simply attempts to “explain science.” They also carry history, cultural teachings, relationships to land, navigation knowledge, seasonal information, or spiritual meaning.
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When studying cultural astronomy, it is important to remember that every tradition has its own context. Indigenous astronomical knowledge in particular should be learned from reliable sources connected to the communities whose knowledge is being discussed.
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While the sky is shared, the stories we tell about it are wonderfully diverse.
So, the things that you can see in the night sky tonight are the same as those that the first humans saw when they themselves looked up. Perhaps some people, with finely tuned eyesight, can make out a few more details or even notice a dim star that you can’t. However, until the telescope was turned to the sky in the early 1600s, the sky of 10 000 years ago and the sky of today mostly reveal the same objects and events.
Celestial bodies became a source of wonder because they had this huge presence over the lives of early men. Let's watch a documentary to understand how this connection and fascination with the cosmos started.
Celestial bodies became a source of wonder because they had this huge presence over the lives of early men. Let's watch a documentary to understand how this connection and fascination with the cosmos started.
Activity:
What We See, What We Saw
Use the worksheet below to share, collect, and evaluate your ideas about visible sky objects.
Spend some time by yourself thinking of answers; then go up and speak with 3 other people and see if you can come to a consensus.
What We See, What We Saw
Use the worksheet below to share, collect, and evaluate your ideas about visible sky objects.
Spend some time by yourself thinking of answers; then go up and speak with 3 other people and see if you can come to a consensus.
| sky_of_our_ancestors.docx |
You would have a ton of questions unanwered, like why does the Sun disappear every night? Why does the Moon change shape? Why do some stars move together, and other bright objects seem to move on their own path? What causes a "star" to "fall from the sky"?
Visiting the Stars
Get SEGA star planetarium ready.
ould the sky predict seasons, weather, migration, or changes in the environment?
The StarsOn a very dark night, far away from city lights, thousands of stars can be visible to the unaided eye.
They are not all identical.
Some appear brighter.
Some appear dimmer.
Some have slightly different colours.
Some look white, while others may appear bluish, yellowish, orange, or reddish.
Stars also appear to move across the sky during the night.
Like the apparent movement of the Sun, much of this motion happens because Earth is rotating.
Most stars seem to move in great arcs across the sky.
But if you are in the Northern Hemisphere and look toward the north, one star appears to move very little.
That star is Polaris, commonly called the North Star.
Polaris happens to lie very close to the direction Earth's north rotational axis points.
Because of this, other stars appear to circle around it during the night.
For centuries, this made Polaris extremely useful for navigation.
If you can find Polaris, you can find approximately north.
Why Do the Stars Disappear During the Day?The stars do not actually disappear when the Sun rises.
They are still there.
The problem is that sunlight enters Earth's atmosphere and scatters in many directions.
This scattered sunlight makes the daytime sky extremely bright.
The stars are simply too faint for our eyes to see against that bright background.
Once the Sun sets and the sky becomes dark again, they become visible.
Patterns in the StarsStars seem to form patterns when viewed from Earth.
Humans have been identifying these patterns for thousands of years.
Some patterns became constellations.
People used stars to help with:
navigation,
seasonal calendars,
agriculture,
ceremonies,
storytelling,
and remembering important cultural knowledge.
The appearance of certain stars at particular times of year could act almost like a calendar signal.
If a familiar star group appeared shortly before sunrise during a certain season, people could connect its appearance with environmental events such as changing weather, animal migration, planting, or harvesting.
The sky became a giant repeating clock.
The MoonThe Moon changes appearance throughout the month.
Sometimes it appears as a thin crescent.
Sometimes half of it appears illuminated.
Sometimes we see a bright full Moon.
These changes are called phases.
The Moon is not producing its own visible light.
We see sunlight reflecting from its surface.
As the Moon moves around Earth, we see different amounts of its sunlit half.
A complete cycle of lunar phases takes about 29.5 days.
Because this cycle is regular and easy to observe, many human calendars have been based partly or entirely on lunar cycles.
The Moon also appears to change position against the background stars from night to night because it is orbiting Earth.
It rises and sets at different times depending on its position in its orbit.
Careful observers could therefore use the Moon to track time and repeating cycles.
The Five Wandering PlanetsMost stars keep the same basic pattern relative to one another.
But ancient sky watchers noticed something strange.
A few bright objects slowly changed position among the stars.
These became known as planets.
The word planet comes from an ancient Greek word meaning something like wanderer.
Five planets can be seen from Earth without a telescope:
Mercury
Venus
Mars
Jupiter
Saturn
They are not always visible.
Sometimes a planet is visible in the evening.
Sometimes it appears before sunrise.
Sometimes it lies in the same general direction as the Sun and becomes difficult or impossible to see.
Their positions change because both Earth and the other planets are moving around the Sun.
One particularly strange behaviour is called retrograde motion.
Normally a planet appears to move slowly in one direction against the background stars.
But occasionally it seems to stop, move backward for a while, and then continue forward again.
The planet is not actually reversing its orbit.
The effect happens because Earth and the other planet are moving around the Sun at different speeds.
To ancient observers, however, this behaviour would have been extremely mysterious.
Unexpected VisitorsNot everything in the sky follows an obvious daily pattern.
Sometimes something completely unexpected appears.
MeteorsA streak of light sometimes called a “shooting star” is actually a meteor.
It occurs when a small piece of space debris enters Earth's atmosphere at high speed and heats the air around it.
If part of the object survives and reaches the ground, that remaining piece is called a meteorite.
CometsComets are icy bodies that orbit the Sun.
When a comet travels closer to the Sun, some of its frozen material turns into gas and dust.
This can create a glowing coma and a long tail.
A bright comet can remain visible for days or weeks and may look dramatically different from ordinary stars.
For people who did not know what comets were, their sudden appearance could be astonishing.
Guest StarsHistorical observers also recorded temporary “new stars.”
Some of these may have been novae or supernovae.
A supernova is an enormous stellar explosion.
One famous example appeared in the year 1054. Historical records from several regions describe an unusually bright object appearing in the sky.
Today, astronomers associate that event with the object we call the Crab Nebula.
The Milky WayOn a dark night away from city lights, you may see a pale glowing band stretching across the sky.
That is the Milky Way.
Before modern astronomy, people interpreted this strange band in many different ways.
Today we know that we live inside a huge galaxy containing hundreds of billions of stars.
When we look toward the dense regions of our galaxy's disk, the light of enormous numbers of distant stars blends together into the cloudy band we see.
In other words:
when you look at the Milky Way, you are looking through the galaxy you live inside.
Did Ancient People Understand Sky Patterns?There is enormous evidence that people observed the sky carefully long before modern science.
Archaeological sites, written records, calendars, navigation traditions, oral histories, architecture, and alignments with sunrise, sunset, or particular stars show that many societies developed sophisticated astronomical knowledge.
People tracked:
the seasons,
solstices and equinoxes,
lunar cycles,
planetary movement,
the appearance of particular stars,
eclipses,
comets,
and other unusual events.
Their explanations of why these things happened varied widely.
But careful observation did not begin with modern telescopes.
Humans have been astronomers for thousands of years.
What Would the Universe Have Looked Like to Them?Now imagine trying to construct a model of the universe using only your eyes.
The ground beneath you feels still.
The sky appears to rotate around you.
The Sun rises and sets.
The Moon moves across the stars.
The planets wander.
From this evidence alone, it would be completely reasonable to wonder whether Earth sat at the centre of everything.
Only after centuries of increasingly precise observations did humans begin developing better models of how Earth, the planets, the Sun, and the stars actually move.
And that is one of the most important ideas in science:
We build explanations from the evidence available to us.
As our observations improve, our explanations can change.
The people who watched the sky thousands of years ago were asking many of the same questions astronomers still ask today:
What is out there?
How does it move?
Why does it behave that way?
And what can the sky tell us about our place in the universe?
