How Old Is the Universe?

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How Old is the Universe?

Until recently, astronomers estimated that the Big Bang occurred between 12 and 14 billion years ago. To put this in perspective, our own Solar System is thought to be 4.5 billion years old. Humans have existed for only a few million years.

A)DRAW THESE EVENTS & TODAY ON THE TIMELINE BELOW

HINT: 1 inch can equal 1 billion years, and1 billion = 1,000 million

My Space Timeline

How Do We Know It’s So Old?

Astronomers estimate the age of the universe in two ways:

by looking for the oldest stars; and

by measuring the rate the universe is expanding and extrapolating (calculating) back to the Big Bang

ABOUT STARS:How old a star gets, called the life cycle of a star, depends on its mass. High mass stars are much brighter than low mass stars, so they rapidly burn through their supply of hydrogen fuel just like a brighter light bulb uses up more electricity.

A star like our Sun has enough fuel in its core to burn at its current

brightness for about9,000,000,000 years (9 billion).

A star that is twice as massive as our Sun will burn through its fuel

supply in only 800,000,000 years (800 million).

A 10 solar mass star(a star that is 10 times more massive than the

Sun) burns nearly a thousand times brighter and has only a

20,000,000 year (20 million) fuel supply.

But a star that is half as massive as the Sun burns slowly enough

for its fuel to last more than 20,000,000,000 years(20 billion).

The Stars Astronomers Study

Astronomers can say how old the universe is at the least by studying how large, and how old, stars are – especially stars in clusters.

Globular clusters are a dense collection of roughly a million stars. We live on the outskirts of our galaxy, sothe next nearest star to our Sun is Proxima Centauri. However, if we lived near the center of a globular cluster there would be several hundred thousand stars closer to us than Proxima Centauri!

Since all of the stars in a globular cluster formed at roughly the same time, they can serve as cosmic clocks. When scientistslook at where one cluster is in space compared to another, they get a pretty good idea of the age of all the different galaxies.

Make Your Own Expanding Universe!

1st– use a marker to make 10 dots on a deflated balloon; number each dot then measure & record how far away they are from Dot #1

2nd – blow 3-4 normal breaths into the balloon to inflate it half way & bend down the end under a paperclip so no air escapes; measure & record how far away each dot is from Dot #1 now

3rd– repeat this process after you double the amount of air in the balloon then answer the Observation Statements on the next page

Science in Hawai‘i: Nā Hana Ma Ka Ahupua‘a – A Culturally Responsive Curriculum

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B. OBSERVATION STATEMENTS (Fill in the blanks)

B.1 After expanding the balloon once, the Dots #2-9 moved

______Dot #1

B.2 After expanding the balloon again, the Dots #2-9 moved

______Dot #1

B.3 Each time the size of all the dots themselves ______.

We can use this balloon activity to make inferences from observed facts just like astronomers do about how the universe expands – it’s whatdetectivesdo to solve a crime by retracing the path of a bullet!

B.4 Fill in the blanks in the table below.

Observation / Inference
The dots on a balloon move ______from Dot #1 when the balloon expands / Since Dots #2-9 appear to move ______from Dot #1, they must have been ______before the balloon expanded
The dots on a balloon become ______when the balloon expands / Since Dots #2-9 appear to get ______as the balloon expands, they must have been ______before the balloon expanded

WHAT DO THESE INFERENCES MEAN?

If you imagine the balloon is the whole universe, and each dot is a galaxy in the universe, you can see why scientists think the universe used to be smaller long ago, and objects in galaxies used to be closer together.

This is one of the main reasons scientists created the scientific theory called the Big Bang. The table on the next page shows other things scientists have observed in the last century, and what they think this information shows about the age of the universe.

Science in Hawai‘i: Nā Hana Ma Ka Ahupua‘a – A Culturally Responsive Curriculum

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Important Astronomy Discoveries about the Age of the Universe

Scientists have been looking carefully at the distant universe for nearly 100 years, using ever more powerful telescopes, like the Hubble. This table shows what they found, and what it may mean.

Observation / Inference
Almost all galaxies are red-shifted(i.e. their electro-magnetic light waves get longer & move towards the red end of the spectrumthe farther away they are). / Almost all galaxies are moving away from the Milky Way.
The most distant galaxies exhibit the greatest red-shift. / The most distant galaxies are moving away the fastest.
The Hubble Constant shows that all objects far off in space appear to be moving away from Earth at 50-100 kilometers per second for every kiloparsec (3250 light years of space). / The Universe has been expanding for 8 to 15 billion years.
The Cosmic Background Explorer (NASA’s Explorer 66 or COBE space satellite) found that the temperature of intergalactic space was not zero. / The universe has not yet cooled from the rapid Big Bang expansion.

RED-SHIFTTHE HUBBLE CONSTANT NASA

The lines or wavesThis table shows how

in the spectrum ofthe red-shift & speed of

our Sun areon thedistant galaxies (on the

left& the shifted,vertical axis, the left line)

longer electro-increasethe more

magnetic waves of distant those faraway

asupercluster ofgalaxies are from our

distant galaxies galaxy (on the horizontal

are on the right. axis, the bottom line)

Science in Hawai‘i: Nā Hana Ma Ka Ahupua‘a – A Culturally Responsive Curriculum

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DO NOT COPY – NO BLANK PAGE NEEDED – CANNOT DELETE

Science in Hawai‘i: Nā Hana Ma Ka Ahupua‘a – A Culturally Responsive Curriculum

Retrieved & adapted from: