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A few years ago, I learned that one of the quasars was visible with a small telescope. This quasar is called 3C 273. This magnitude 12.9 object is found in the constellation Virgo the Virgin.
Mysterious Objects
I remember news accounts of these objects during the 1960’s. Their extreme distance and extreme energy baffled astronomers. The name quasar means “quasi-stellar radio source”. Today, we know that they are galactic, rather than star-like. They have a new name: Active Galactic Nuclei, or AGN’s.
I Get to See a Quasar
I viewed 3C 273 with a 10” Dobsonian telescope at a rural site. Since it looked like an ordinary star, I needed to use a chart to identify it.
The view of 3C 273 could be called underwhelming, but I was excited! I got to look at something which was a great mystery a few decades ago. Something else was amazing: the literature tells us that 3C 273 is two billion light-years from us.
How Far is Two Billion Light-Years?
Viewing something two billion light-years away triggered my curious mind. I have tried to express “two billion light-years” with terms from our everyday experience.
Two
This is the easy part! When you see two apples, you know that two apples are there, not one or six.
Billion
One billion, or 1,000,000,000 is precise number in mathematical terms. However, I found that the word “billion” in everyday speech simply means “a very large quantity.”
If you questioned a billionaire, you would probably find that the “billion” is based on estimated values of assets.
What if you walked a billion paces? That would take you around the world 39 times.
If someone showed me three piles of gravel, and asked me which one had a billion stones, I would have no way to make a good guess.
So, in practical terms, a billion is uncountable.
Light-years
Visualizing a light year is more challenging than visualizing the number one billion. A light-year is the distance traveled by electromagnetic radiation in one year.
I remember watching the Apollo 11 lunar mission. If Mission Control asked a question, it took 1.5 seconds for it to reach the Moon and another 1.5 seconds for the answer to return.
The distance to the Moon is about ten times the circumference of the earth. Many people have traveled this far.
Unfortunately, we are trying to visualize a light-year, not 1.5 light-seconds.
The Voyager 1 space probe is only 23 light-hours away, after a very speedy 47 years.
So, I call a light-year unimaginable.
Two Billion Light-years
To sum it up, the distance to 3C 273 is an unimaginable distance, times an uncountable quantity, times two.
One More Thing…
Despite its distance, 3C 273 can be viewed with modest optical aid. How can we describe its energy output?
RealSimpleAstronomy
Real Simple Astronomy 
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