Before You Go Out to the Sidewalk...

By Ray Cash.

Educate yourself, then you can inform, even entertain, others!

As soon as you put your telescope on the sidewalk and invite passersbys to "take a peek," you'll notice several things, not the least of which how appreciative most folks are (and how many have never looked through a telescope); but even more significantly, you'll notice how many questions people have. It is important that you have answers.

Here are some of the most common questions, and their answers. One more you should be ready to answer is "Why are you doing this?"

Be spontaneous, be creative... Do a little research... Try to answer questions in a manner that folks will understand and remember. If they don't ask questions, do an "Alex Trebek," give them answers!

Many of the most entertaining sidewalk astronomers have little stories to tell, which help people remember some of the answers:

"If you were in a spaceship going 60 miles an hour 24 hours a day:

Visualized scale models are also useful:

If the Sun were the size of a bowling ball (8" diameter):

over half a mile (mile=1760 yards) from a bowling ball sized Sun.

The nearest bowling ball sized star would be 4,300 miles away--the average distance between stars in our Milky Way galaxy. (1,000 miles=1 light year with this model).

[from Guy Ottewell's The Thousand-Yard Model ]

A scale model I've adopted from Robert Burnham's excellent 3-volume Celestial Handbook, shrinks the distance between the Sun and Earth (Sun=8"; Earth=peppercorn, 26 yards away, from above, remember?) down to one-inch away! On this scale, the Sun is a mere pinpoint of light, the whole solar system is about two yards in diameter, and a light-year equals a mile! This means the nearest pinpoint-star would be about 4.3 miles away!

To get an idea of the size of our galaxy, Burnham shrinks the scale model down even further:

As you can see, the distances between stars in galaxies are enormous (even within a scale model). The distances between galaxies are not so great, at least relatively speaking: The distance to our nearest large galaxy, Andromeda (2.9 million light years), is about 29-times the Milky Way's diameter (100 thousand light years). If your fist were the Milky Way, hold it high over your head--Andromeda would be another fist-sized galaxy at your feet!!

How about numbers? How can we get an idea of what a million, or billion of anything is? Again, a scale model is useful here. David Chandler, in his booklet, Exploring the Night Sky with Binoculars, uses a grain of sand as a unit:

Bring a reference book with you (one with pictures or maps is useful, especially if you will be looking at the moon). Write some notes down--perhaps even tape some of these scale models to your scope!