Assuming you are not above the Arctic circle and not too close to the equator… if you could look right at the Sun (when the night is exactly half over) – by looking through the Earth – which cardinal direction would you be facing? East, West, North, or South?
Your hands and arms help you see the orbits of Mercury and Venus and the shape of solar system
Question: If you could see the orbit of Venus would it fill the whole sky?
The answer might surprise you!
You can use your hands and arms to see the size of the orbits of the solar system’s inner planets: Mercury and Venus.
Imagine (as pictured below) if the orbit of Mercury were visible as a red oval and the orbit of Venus were visible in green.
Physical Astronomy – see Mercury and Venus orbits
Caution! Do not look directly at the Sun without proper solar safety glasses on.
Turn toward the Sun, hold your arms out straight, hands up in the air with fingers spread wide and thumbs touching. Your pinky fingers now span the width of the orbit of Mercury and your elbows span the width of the orbit of Venus.
Both of the entire orbits of Mercury and Venus orbits would be visible in the sky all at once – if they could be made visible during the day.
Ptolemaeus, Alphonsus, and Arzachel… the names of three massive, interlocking craters on the Moon. These three craters tell the story of the ancient Moon’s creation and evolution. It’s a story of violent bombardments and oceans of lava. We can use light and shadows to reveal the shapes and deep history of these features.
Most people think of astronomy a science of light. But, light creates shadows when it hits things. Those features that lie in the shadows, the dark parts and seemingly just-in-the-way-of-the-light parts, are just as important as those that shine brightly. These dark shadows form most of the mass of all galaxies, house stellar nurseries, reveal old lava rivers on the Moon, and create curious plays of light and dark. These can play tricks on our eyes and make patterns appear.
Let’s do some Physical Astronomy. The experience will help you to understand the movement of the earth and sun through the seasons. You will build a scientific instrument that is also a fun garden decoration and you will be able to track the Groundhog’s Shadow all Spring!
Now, turn a little bit to the left, keeping both hands pointing at the sun.
Swing your left arm out until it is pointing in the opposite direction from the sunset. Bring your hands together again and repeat this swinging motion.
Bring your hands together again and point them both at the sun. This time, instead of swinging, bounce your left hand, leftward, some number of times… (14 is perfect if you can do it) …until it is pointing in the completely opposite direction from the Sun at sunset. Your left hand should now be pointing East.
Was the moon at any one of those 14 hand bounce spots? That is the age of the moon in days.