We have discovered Mars just as it was when it was first discovered: using our unaided eyes. Just about 400 years ago, Galileo discovered a new way of looking at Mars: through a telescope.
DIGITAL EFFECT: Mars Through Telescope
Zoom up a “telescopic” view of Mars, attached to Mars, in an “eyepiece ring.”
VISUAL 2 (optional still): Eyepiece Ring
VISUAL 3 (still): Mars Through a Telescope
This red circle represents the eyepiece of a telescope, and we are looking at one of the clearest photographs ever taken of Mars though a large telescope on the Earth.
What features do you see in this photograph?
[Color, dark shapes, white polar cap.]
The features—the light and dark areas—are not so very sharp. In fact, they are kind of blurry.
Why do you think that this picture looks so blurry?
[Atmospheric turbulence on Earth.]
Now we’ll see Mars as it would look through a large telescope.
[Fade off Mars Through Telescope.]
DIGITAL EFFECT: Fuzzy Mars
If possible, turn on a special effect to make your native Mars model look fuzzy, as though looking through atmosphere. If unavailable, use the alternative movie or still.
VISUAL (alternative movie or still): Fuzzy Mars
[Use the “Pause,” “Play,” “Fade Off,” and “Fade On” effects as needed with the video clip.]
There it is. See how our atmosphere is changing, blurring the image. But every once in a while the atmosphere will stabilize, and Mars will become clear for an instant. This is a simulation of the “live” view through a large telescope.
Any photograph we take through any telescope on Earth must also look through the constantly changing atmosphere of the Earth. The turbulent air makes stars twinkle, and planets look blurry. Every minute or so on very clear nights the atmosphere directly along our line of sight may happen to be less turbulent than normal, and for a fraction of a second, we might get an unusually clear view. But cameras don’t know when these moments will occur, and record the picture over several tenths of seconds, so they would photograph the blur along with the clear. So astronomers observing from the Earth even today rely on their eyesight and memory, and sketch details by hand.
There are some fine details in this view of Mars that I can just barely make out. As astronomers, we would try to establish as much detail as possible by seeing if there are any visible features we all agree are real.
Telescope Observing and Sketching Activity
DIGITAL EFFECT (optional): Atmosphere
Turn up atmosphere and the Sun to give more light for people to sketch.
Distribute paper, turn on reading lights full.
Here is your chance to pretend you are an astronomer, trying to help decide what the surface features are. Let me give each of you a piece of paper. On the top half there are two sketches of your telescope eyepiece, with a blank disk of Mars ready for you to complete.
Now, to help determine what surface features are there, please sketch in the dark features on the surface of Mars. Watch for the brief moments of clarity, and then get as much detail as you can.
We will observe for just a few minutes, and then hold a brief conference to reach our joint conclusions. There is a second blank disk on your paper in case you don’t like the way your drawing is coming out, and want to start over.
DIGITAL EFFECT (optional): Atmosphere Off Turn off atmosphere and the Sun. Go through three periods of clarity. DIGITAL EFFECT: End Fuzzy Mars Turn up atmosphere and the Sun, and turn off Mars’ special effect.
Please recall the telescope photograph of Mars that you saw a few minutes ago.
Which contains more details, your drawings or that photograph?
Any one of your drawings has more detail than that photograph which was one of the best ever taken from the planet Earth.
Compare your sketch with the person sitting next to you. Did they see some details you didn’t?
Walk around the room, select one or two examples and show using the opaque projector. These sketches are all different, although some of the features show up on most of them. Ask students to name the features on the projected image that are similar to the features on their own drawing.
Why do you think each of us made a different sketch of the same view?
[Differing skills of observers, different moments of observation, different choices of what to watch.]
There are always differing interpretations of what is really there for something as new and difficult to observe as this. We cannot agree perfectly on what is really there, but we can come to agreements on broad structure. Even with all the inherent limitations of drawings, many of the best and most detailed images of Mars have come from drawings by amateur and professional astronomers, not from photographs.
In modern day astrophotography, extremely clear images are achieved by capturing a series of dozens of images and then “stacking” or adding them together to overcome the blurring effects of Earth’s atmosphere.
VISUAL 4 (optional movie): Video Photo Sketch
Show the series of comparison images from the Optical Data Corporation’s “Astronomy” laser videodisc or slides, showing first a telescope photograph of Mars at a given time, then a corresponding astronomer’s drawing of the same side of Mars created at the same time as the photograph. (See media list.)
DIGITAL EFFECT: End Video Photo Sketch