If you have young people in the house who are curious about astronomy, here’s an idea to spark their interest. It’s a little game I call “What’s going on with the moon tonight?”
It’s easy to forget about the moon in this age of space stations and Mars rovers—Perseverance, NASA’s latest, just made a spectacular touchdown on the red planet—but the reality is that no other astronomical body, apart from the sun, has more effect on our daily life.
Yet how many adults, let alone children, can explain why the moon has phases, or why we see only one face of it? Or whether there’s a dark side? Or why a full moon looks bigger on the horizon?
That last one is admittedly a bit tricky. The human brain is wired to regard large, sharply-defined objects as nearby, and blurry, fuzzy objects as far away. Faced with a large, clear object on a blurry—but obviously nearer—horizon, our poor brains dutifully inflate the moon to more impressive size. It’s a mean trick of the brain, really, but I suppose it’s a matter of perspective.
So, “What’s going on with the moon tonight?” Here’s how it works: once a week, take the wee ones outside at night when it’s clear and ask why the moon looks the way it does on that particular date. Then be prepared to answer some common questions. In March, one of those might be “why is the moon dark on the 13th and full on the 28th?” Or, if the date happens to be May 26, it might be “why is the moon smokey-red and dim?”
These four mysteries—phases, new moon, full moon, and lunar eclipse—can be explained with one fun demonstration. You’ll need a lamp with a single bulb, a white foam ball, a swivel chair, a pencil, and a dark room.
Place the lamp on a table, stab the foam ball with the pencil and ask your budding astronomer to hold it up. She should be sitting in the swivel chair facing the light. The lightbulb is the sun, the foam ball is the moon, and the budding astronomer is the earth. The rotating chair is time.
Now slowly turn the chair counter-clockwise to simulate one month (roughly). If the room is dark enough, then as the chair turns the foam moon-ball will wax, become full (when facing directly away from the light), then wane and become completely dark (when facing directly toward the light). After one rotation, you will have completed one lunar cycle in all its phases. For the lunar eclipse, have your astronaut turn again until the moon-ball falls within the shadow of her head. For a solar eclipse, turn again until the moon neatly blocks out the sun.
It’s a simple demonstration, and it would need to add a tilt to the moon’s orbital plane to be more precise, but if your junior astronaut can explain the phases of the moon after playing with this little kitchen-orrery, she will be ahead of several adults I know!
Got an astronomy question you’d like to see answered? Let me know: dennis6ps@gmail.com .
Stargazing by Dennis Vanderspek
